C=
;9)' .2//2%B/2+)' $%073' -$&%"(' v>0-' $-' 39)' "#)*"&)' 21' 39)' 362' $%073' -$&%"(-' vC' "%+' vQX %"/)(45
v >0- = CBBQB ( v C + v Q )
Q=
@K7"3$2%-'C='"%+'Q='."%',)'7-)+'32')M0*)--'39)'$%073'-$&%"(-'vC'"%+'vQ'$%'3)*/-'21'39)$* +$11)*)%3$"('"%+'.2//2%B/2+)'.2/02%)%3-'"-'12((26-:
v C = v >0- ! v >. ⁄ Q
T=
v Q = v >0- + v >. ⁄ Q
'U=
"%+
;9)-)')K7"3$2%-'."%'$%'37*%'()"+'32'39)'0$.32*$"('*)0*)-)%3"3$2%'$%'S$&>'Q>U>'''''' 1
1
v1 " !
vIcm 2
" !
! "
vId #2
! "
vId #2 2
v2 " !
Figure 2.4 O)0*)-)%3"3$2%'21'39)'-$&%"('-27*.)-'vC'"%+'vQ'$%'3)*/-'21'39)$*'+$11)*)%3$"('"%+'.2//2%B/2+)' .2/02%)%3->
EXERCISES 2.2' G2%-$+)*'"%'20'"/0'39"3'$-'$+)"(')M.)03'39"3'$3-'20)%B(220'&"$%'$'='CFT>';9)'20'"/0'$-'7-)+'$%'"'1))+B ,".8'.$*.7$35'"%+'39)'#2(3"&)-'"00)"*$%&'"3'362'21'$3-'39*))'-$&%"('3)*/$%"(-'"*)'/)"-7*)+>'A%')".9'21 39)'12((26$%&'."-)-5'7-)'39)'/)"-7*)+'#"(7)-'32'1$%+'39)')M0).3)+'#"(7)'21'39)'#2(3"&)'"3'39)'39$*+'3)*B /$%"(>'H(-2'&$#)'39)'+$11)*)%3$"('"%+'.2//2%B/2+)'$%073'-$&%"(-'$%')".9'."-)>'<"='vQ'='F'`'"%+'vT'= Q `X'<,='vQ'='+V'`'"%+'vT'='−CF'`X'<.='vC'='C>FFQ'`'"%+'vQ'='F>DDc'`X'<+='vC'='−T>E'`'"%+'vT'='−T>E'`> Ans. <"='vC'='−F>FFQ'`5'v>.'='Q'/`5'v>0-'Z'−C'/`X'<,='vC'='+V>FC'`5'v>.'='−CF'/`5'v>0-'='V>FFV'!'V `X <.= vT'='−U'`5%v>.'='−U'/`5'v>0-'= C'`X'<+='vQ'='−T>EFTE'`5'v>.'='−T>E'/`5'v>0-'!'−T>E'`
57
58 Chapter 2 Operational Amplifiers 2.3' ;9)'$%3)*%"('.$*.7$3'21'"'0"*3$.7("*'20'"/0'."%',)'/2+)()+',4'39)'.$*.7$3'-926%'$%'S$&>'@Q>T>'@M0*)-vT'"-'"'17%.3$2%'21'vC'"%+'vQ>'S2*'39)'."-)'A-'='CF'/Hd`5'?'='CF'8Ω5'"%+' µ'='CFF5'1$%+'39)'#"(7)'21 39)'20)%B(220'&"$%'$> Ans. vT'= µA-?
Figure E2.3
2.2 The Inverting Configuration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v>>' ;9)' 273073' 21' 39)' 2#)*"((' .$*.7$3' $-' 3"8)%' "3' 3)*/$%"(' T' <$>)>5 ,)36))%' 3)*/$%"(' T' "%+
2.2 The Inverting Configuration
Figure 2.5 ;9)'$%#)*3$%&'.(2-)+B(220 .2%1$&7*"3$2%>
&*27%+=>';)*/$%"('T'$-5'21'.27*-)5'"'.2%#)%$)%3'02$%3'1*2/'69$.9'32'3"8)'39)'2730735'-$%.)'39) $/0)+"%.)'()#)('39)*)'$-'$+)"((4'[)*2>';97-'39)'#2(3"&)'vB'6$(('%23'+)0)%+'2%'39)'#"(7)'21'39)'.7*B *)%3'39"3'/$&93',)'-700($)+'32'"'(2"+'$/0)+"%.)'.2%%).3)+',)36))%'3)*/$%"('T'"%+'&*27%+>
2.2.1 The Closed-Loop Gain Y)'%26'6$-9'32'"%"(4[)'39)'.$*.7$3'$%'S$&>'Q>V'32'+)3)*/$%)'39)'0-.4$1/-..(*',!"*A5'+)1$%)+'"-
v A ≡ BBBBBB v> Y)'6$(('+2'-2'"--7/$%&'39)'20'"/0'32',)'$+)"(>'S$&7*)'Q>E<"='-926-'39)')K7$#"()%3'.$*.7$35 "%+'39)'"%"(4-$-'0*2.))+-'"-'12((26-:';9)'&"$%'$'$-'#)*4'("*&)'<$+)"((4'$%1$%$3)=>'A1'6)'"--7/) 39"3' 39)' .$*.7$3' $-' ^62*8$%&_' "%+' 0*2+7.$%&' "' 1$%$3)' 273073' #2(3"&)' "3' 3)*/$%"(' T5' 39)%' 39) #2(3"&)' ,)36))%' 39)' 20B"/0' $%073' 3)*/$%"(-' -927(+' ,)' %)&($&$,(4' -/"((' "%+' $+)"((4' [)*2> L0).$1$."((45'$1'6)'."(('39)'273073'#2(3"&)'vB5'39)%5',4'+)1$%$3$2%5
v v Q ! v C = BBBBBB = F ' $ A3' 12((26-' 39"3' 39)' #2(3"&)' "3' 39)' $%#)*3$%&' $%073' 3)*/$%"('' ;9"3' $-5 ,)."7-)'39)'&"$%'$'"00*2".9)-'$%1$%$345'39)'#2(3"&)'vC'"00*2".9)-'"%+'$+)"((4')K7"(-'vQ>'Y) -0)"8'21'39$-'"-'39)'362'$%073'3)*/$%"(-'^3*".8$%&')".9'239)*'$%'023)%3$"(>_'Y)'"(-2'-0)"8'21'" ^#$*37"('-92*3'.$*.7$3_'39"3')M$-3-',)36))%'39)'362'$%073'3)*/$%"(->'!)*)'39)'62*+';)8&,/3'-927(+ ,)')/09"-$[)+5'"%+'2%)'-927(+'*1&'/"8)'39)'/$-3"8)'21'094-$."((4'-92*3$%&'3)*/$%"(-'C'"%+'Q 32&)39)*'69$()'"%"(4[$%&'"'.$*.7$3>'H'#!%&),-*47.%&*0!%0)!&'/)"%-'39"3'69"3)#)*'#2(3"&)'$-'"3'Q 6$(('"732/"3$."((4'"00)"*'"3'C',)."7-)'21'39)'$%1$%$3)'&"$%'$>'e73'3)*/$%"('Q'9"00)%-'32',)'.2%B %).3)+'32'&*27%+X'397-'vQ'='F'"%+'vC'='F>'Y)'-0)"8'21'3)*/$%"('C'"-',)$%&'"'#!%&),-*'%.)"1f 39"3'$-5'9"#$%&'[)*2'#2(3"&)',73'%23'094-$."((4'.2%%).3)+'32'&*27%+>' P26'39"3'6)'9"#)'+)3)*/$%)+'vC'6)'"*)'$%'"'02-$3$2%'32'"00(4'?9/J-'("6'"%+'1$%+'39) .7**)%3')C'39*27&9'?C'<-))'S$&>'Q>E='"-'12((26-:
v> ! vC v> ! F v B = BBBBBBBBBBBB B = BBBBB> ) C = BBBBBBBBBBBBBB ?C ?C ?C Y9)*)'6$(('39$-'.7**)%3'&2\'A3'."%%23'&2'$%32'39)'20'"/05'-$%.)'39)'$+)"('20'"/0'9"-'"%'$%1$%$3) $%073'$/0)+"%.)'"%+'9)%.)'+*"6-'[)*2'.7**)%3>'A3'12((26-'39"3')C'6$(('9"#)'32'1(26'39*27&9'?Q'32 39)'(26B$/0)+"%.)'3)*/$%"('T>'Y)'."%'39)%'"00(4'?9/J-'("6'32'?Q'"%+'+)3)*/$%)'vBX'39"3'$-5
;97-5
vB = vC ! )C ?Q v = F ! BBBBB> ? Q ?C v ? BBBBBB = ! BBBBBQ v> ?C
59
60 Chapter 2 Operational Amplifiers
5 3
4 ! 1
" 6
2
Figure 2.6 H%"(4-$-'21'39)'$%#)*3$%&'.2%1$&7*"3$2%>';9)'.$*.()+'%7/,)*-'$%+$."3)'39)'2*+)*'21'39)'"%"(4-$-' -3)0->
69$.9'$-'39)'*)K7$*)+'.(2-)+B(220'&"$%>'S$&7*)'Q>E<,=%$((7-3*"3)-'39)-)'-3)0-'"%+'$%+$."3)-',4 39)'.$*.()+'%7/,)*-'39)'2*+)*'$%'69$.9'39)'"%"(4-$-'$-'0)*12*/)+> Y)'397-'-))'39"3'39)'.(2-)+B(220'&"$%'$-'-$/0(4'39)'*"3$2'21'39)'362'*)-$-3"%.)-'?Q'"%+'?C> ;9)' /$%7-' -$&%' /)"%-' 39"3' 39)' .(2-)+B(220' "/0($1$)*' 0*2#$+)-' -$&%"(' $%#)*-$2%>' ;97-' $1 ? Q ⁄ ? C = CF '"%+'6)'"00(4'"3'39)'$%073''e)."7-)'21'39)'/$%7-'-$&%'"--2.$"3)+'6$39'39)'.(2-)+B(220'&"$%5'39$-'.2%1$&B 7*"3$2%'$-'."(()+'39)'!"#$%&!"'*0."3!')%,&!.">
2.2 The Inverting Configuration
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⁄ ? C'39"3'$-'/7.9'-/"(()*'39"%'$',73'$-'-3",()'"%+'0*)+$.3",()>';9"3'$-5'6)'"*)'3*"+$%&'&"$% 12*'"..7*".4>
2.2.2 Effect of Finite Open-Loop Gain ;9)'02$%3-'W7-3'/"+)'"*)'/2*)'.()"*(4'$((7-3*"3)+',4'+)*$#$%&'"%')M0*)--$2%'12*'39)'.(2-)+B (220'&"$%'7%+)*'39)'"--7/03$2%'39"3'39)'20B"/0'20)%B(220'&"$%'$'$-'1$%$3)>'S$&7*)'Q>I'-92639)' "%"(4-$->' A1' 6)' +)%23)' 39)' 273073' #2(3"&)' vB5' 39)%' 39)' #2(3"&)' ,)36))%' 39)' 362' $%073 3)*/$%"(-'21'39)'20'"/0'6$((',)' v B ⁄ $>'L$%.)'39)'02-$3$#)'$%073'3)*/$%"('$-'&*27%+)+5'39) #2(3"&)'"3'39)'%)&"3$#)'$%073'3)*/$%"('/7-3',)' ! v B ⁄ $> ';9)'.7**)%3')C'39*27&9'?C'."%'%26',) 127%+'1*2/
v> ! ( !vB ⁄ $ ) v> + vB ⁄ $ B ) C = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB = BBBBBBBBBBBBBBBBBBBBBBB ?C ?C
Figure 2.7 H%"(4-$-' 21' 39)' $%#)*3$%& .2%1$&7*"3$2%'3"8$%&'$%32'"..27%3'39)'1$%$3) 20)%B(220'&"$%'21'39)'20'"/0>
;9)'$%1$%$3)'$%073'$/0)+"%.)'21'39)'20'"/0'12*.)-'39)'.7**)%3')C'32'1(26')%3$*)(4'39*27&9 ?Q>';9)'273073'#2(3"&)'vB'."%'397-',)'+)3)*/$%)+'1*2/
v v B = ! BBBBBB ! ) C ? Q $ vB v> + vB ⁄ $ B ?Q = ! BBBBB ' ! ' BBBBBBBBBBBBBBBBBBBBBBB ?C $ G2(().3$%&'3)*/-5'39)'.(2-)+B(220'&"$%'A'$-'127%+'"-
v !?Q ⁄ ?C B A ≡ BBBBBB = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB C + ( C + ?Q ⁄ ?C ) ⁄ $ v>
V=
Y)'%23)'39"3'"-'$'"00*2".9)-'∞5'A'"00*2".9)-'39)'$+)"('#"(7)'21' ! ? Q ⁄ ? C > 'H(-25'1*2/'S$&>'Q>I 6)'-))'39"3'"-'$'"00*2".9)-'∞5'39)'#2(3"&)'"3'39)'$%#)*3$%&'$%073'3)*/$%"('"00*2".9)-'[)*2> ;9$-'$-'39)'#$*37"(B&*27%+'"--7/03$2%'6)'7-)+'$%'27*')"*($)*'"%"(4-$-'69)%'39)'20'"/0'6"-
61
62 Chapter 2 Operational Amplifiers "--7/)+' 32' ,)' $+)"(>' S$%"((45' %23)' 39"3' @K>'V=' $%' 1".3' $%+$."3)-' 39"3' 32' /$%$/$[) 39) +)0)%+)%.)'21'39)' .(2-)+B(220' &"$%' A'2%' 39)'#"(7)'21'39)' 20)%B(220' &"$%'$5'6)' -927(+ /"8)
? C + BBBBBQ '$'$ ?C
Example 2.1 G2%-$+)*'39)'$%#)*3$%&'.2%1$&7*"3$2%'6$39'?C'='C'8Ω'"%+'?Q'='CFF'8Ω> <"= S$%+'39)'.(2-)+B(220'&"$%'12*'39)'."-)-'$'='CFT5'CFU5'"%+'CFV>'A%')".9'."-)'+)3)*/$%)'39)'0)*.)%3"&) )**2*'$%'39)'/"&%$37+)'21'A'*)("3$#)'32'39)'$+)"('#"(7)'21' ? Q ⁄ ? C '<2,3"$%)+'6$39'$'='∞=>'H(-2'+)3)*B /$%)'39)'#2(3"&)'vC'39"3'"00)"*-'"3'39)'$%#)*3$%&'$%073'3)*/$%"('69)%'v>'='F>C'`> <,= A1'39)'20)%B(220'&"$%'$'.9"%&)-'1*2/'CFF5FFF'32'VF5FFF'<$>)>5'+*20-',4'VFg=5'69"3'$-'39)'.2**)-02%+B $%&'0)*.)%3"&)'.9"%&)'$%'39)'/"&%$37+)'21'39)'.(2-)+B(220'&"$%'A\
Solution <"= L7,-3$373$%&'39)'&$#)%'#"(7)-'$%'@K>'V=5'6)'2,3"$%'39)'#"(7)-'&$#)%'$%'39)'12((26$%&'3",()5'69)*)'39) 0)*.)%3"&)')**2*'ε'$-'+)1$%)+'"A ! (? ⁄ ? ) ( ?Q ⁄ ?C )
Q C B × CFF ε ≡ BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
;9)'#"(7)-'21'vC'"*)'2,3"$%)+'1*2/' v C = ! v B ⁄ $ = Av > ⁄ $ '6$39'v>'='F>C'`> A
|G|
CFT CFU CFV
'DF>cT DD>FF DD>DF
ε −D>CIg −C>FFg −F>CFg
v1 −D>Fc'/` −F>DD'/` −F>CF'/`
<,= a-$%&'@K>'V=5'6)'1$%+'39"3'12*'$'='VF5FFF5'|A|'='DD>cF>';97-'"'−VFg'.9"%&)'$%'39)'20)%B(220'&"$% *)-7(3-'$%'"'.9"%&)'21'2%(4'−F>Cg'$%'39)'.(2-)+B(220'&"$%N
2.2.3 Input and Output Resistances H--7/$%&'"%'$+)"('20'"/0'6$39'$%1$%$3)'20)%B(220'&"$%5'39)'$%073'*)-$-3"%.)'21'39)'.(2-)+B(220 $%#)*3$%&'"/0($1$)*'21'S$&>'Q>V'$-'-$/0(4')K7"('32'?C>';9$-'."%',)'-))%'1*2/'S$&>'Q>E<,=5'69)*)
v v> B = ?C ? ) ≡ BBBB> = BBBBBBBBBBBBB )C v> ⁄ ?C P26'*)."(('39"3'$%'L).3$2%'C>V'6)'()"*%)+'39"3'39)'"/0($1$)*'$%073'*)-$-3"%.)'12*/-'"'#2(3"&) +$#$+)*'6$39'39)'*)-$-3"%.)'21'39)'-27*.)'39"3'1))+-'39)'"/0($1$)*>';97-5'32'"#2$+'39)'(2--'21'-$&%"( -3*)%&395'#2(3"&)'"/0($1$)*-'"*)'*)K7$*)+'32'9"#)'9$&9'$%073'*)-$-3"%.)>'A%'39)'."-)'21'39)'$%#)*3B $%&'20B"/0'.2%1$&7*"3$2%'6)'"*)'-37+4$%&5'32'/"8)'?)'9$&9'6)'-927(+'-)().3'"'9$&9'#"(7)'12*'?C> !26)#)*5'$1'39)'*)K7$*)+'&"$%' ? Q ⁄ ? C $-'"(-2'9$&95'39)%'?Q'.27(+',).2/)'$/0*".3$."((4'("*&) <)>&>5'&*)"3)*'39"%'"'1)6'/)&29/-=>'Y)'/"4'.2%.(7+)'39"3'39)'$%#)*3$%&'.2%1$&7*"3$2%'-711)*1*2/'"'(26'$%073'*)-$-3"%.)>'H'-2(73$2%'32'39$-'0*2,()/'$-'+$-.7--)+'$%'@M"/0()'Q>Q',)(26>'
2.2 The Inverting Configuration
L$%.)'39)'273073'21'39)'$%#)*3$%&'.2%1$&7*"3$2%'$-'3"8)%'"3'39)'3)*/$%"(-'21'39)'$+)"('#2(3"&) -27*.)'$'Q>E"=5'$3'12((26-'39"3'39)'273073'*)-$-3"%.)'21'39)'.(2-)+B(220'"/0($B 1$)*'$-'[)*2>
Example 2.2 H--7/$%&'39)'20'"/0'32',)'$+)"(5'+)*$#)'"%')M0*)--$2%'12*'39)'.(2-)+B(220'&"$%' v B ⁄ v > '21'39)'.$*.7$3 -926%'$%'S$&>'Q>c>'a-)'39$-'.$*.7$3'32'+)-$&%'"%'$%#)*3$%&'"/0($1$)*'6$39'"'&"$%'21'CFF'"%+'"%'$%073 *)-$-3"%.)'21'C'RΩ>'H--7/)'39"3'12*'0*".3$."('*)"-2%-'$3'$-'*)K7$*)+'%23'32'7-)'*)-$-32*-'&*)"3)*'39"% C'RΩ>'G2/0"*)'427*'+)-$&%'6$39'39"3',"-)+'2%'39)'$%#)*3$%&'.2%1$&7*"3$2%'21'S$&>'Q>V>
5 4
vx
7
x 6 3
2
! 1
" 8
Figure 2.8 G$*.7$3'12*'@M"/0()'Q>Q>';9)'.$*.()+'%7/,)*-'$%+$."3)'39)'-)K7)%.)'21'39)'-3)0-'$%'39)'"%"(4-$->
Solution ;9)'"%"(4-$-',)&$%-'"3'39)'$%#)*3$%&'$%073'3)*/$%"('21'39)'20'"/05'69)*)'39)'#2(3"&)'$!v !v v C = BBBBBBBBBB = BBBBBBBBBB = F $ ∞
!)*)'6)'9"#)'"--7/)+'39"3'39)'.$*.7$3'$-'^62*8$%&_'"%+'0*2+7.$%&'"'1$%$3)'273073'#2(3"&)'vB>'h%26B $%&'vC5'6)'."%'+)3)*/$%)'39)'.7**)%3')C'"-'12((26-: v> ! F v v> ! vC B = BBBBBBBBBBBB B = BBBBB> ) C = BBBBBBBBBBBBBB ?C ?C ?C
L$%.)'[)*2'.7**)%3'1(26-'$%32'39)'$%#)*3$%&'$%073'3)*/$%"(5'"(('21')C'6$(('1(26'39*27&9'?Q5'"%+'397v ) Q = ) C = BBBBB> ?C
P26'6)'."%'+)3)*/$%)'39)'#2(3"&)'"3'%2+)'C: ? v v C = v C ! ) Q ? Q = F' ! ' BBBBB> ? Q = ! BBBBBQ v > ?C ?C
63
64 Chapter 2 Operational Amplifiers Example 2.2 continued
;9$-'$%'37*%')%",()-'7-'32'1$%+'39)'.7**)%3')T: ?Q F!v Bv ) T = BBBBBBBBBBBBBC = BBBBBBBBBBB ?T ?C ?T > P)M35'"'%2+)')K7"3$2%'"3'C'4$)(+-')U: ?Q v Bv ) U = ) Q + ) T = BBBBB> + BBBBBBBBBBB ?C ?C ?T > S$%"((45'6)'."%'+)3)*/$%)'vB'1*2/ vB = vC ! )U ?U ?Q ? v Bv ? = ! BBBBBQ v > ! BBBBB> + BBBBBBBBBBB ?C ?C ?C ?T > U ;97-'39)'#2(3"&)'&"$%'$-'&$#)%',4 vB ? ? ? BBBBBB = ! BBBBBQ + BBBBBU C + BBBBBQB v> ?C ?C ?T 69$.9'."%',)'6*$33)%'$%'39)'12*/ ? ? ? vB BBBBBB = ! BBBBBQ C + BBBBBU + BBBBBU v> ?C ?Q ?T
P265'-$%.)'"%'$%073'*)-$-3"%.)'21'C'RΩ'$-'*)K7$*)+5'6)'-)().3'?C'='C'RΩ>';9)%5'6$39'39)'($/$3"B 3$2%'21'7-$%&'*)-$-32*-'%2'&*)"3)*'39"%'C'RΩ5'39)'/"M$/7/'#"(7)'02--$,()'12*'39)'1$*-3'1".32*'$%'39) &"$%')M0*)--$2%'$-'C'"%+'$-'2,3"$%)+',4'-)().3$%&'?Q'='C'RΩ>';2'2,3"$%'"'&"$%'21'−CFF5'?T'"%+'?U /7-3',)'-)().3)+'-2'39"3'39)'-).2%+'1".32*'$%'39)'&"$%')M0*)--$2%'$-'CFF>'A1'6)'-)().3'39)'/"M$/7/ "((26)+'<$%'39$-')M"/0()='#"(7)'21'C'RΩ'12*'?U5'39)%'39)'*)K7$*)+'#"(7)'21'?T'."%',)'."(.7("3)+'32 ,)'CF>Q'8Ω>';97-'39$-'.$*.7$3'73$($[)-'39*))'CBRΩ'*)-$-32*-'"%+'"'CF>QB8Ω'*)-$-32*>'A%'.2/0"*$-2%5 $1'39)'$%#)*3$%&'.2%1$&7*"3$2%'6)*)'7-)+'6$39'?C'='C'RΩ'6)'627(+'9"#)'*)K7$*)+'"'1))+,".8'*)-$-B 32*'21'CFF'RΩ5'"%'$/0*".3$."((4'("*&)'#"(7)N e)12*)'()"#$%&'39$-')M"/0()'$3'$-'$%-$&9317('32'$%K7$*)'$%32'39)'/).9"%$-/',4'69$.9'39)'.$*.7$3'$",()'32'*)"($[)'"'("*&)'#2(3"&)'&"$%'6$39273'7-$%&'("*&)'*)-$-3"%.)-'$%'39)'1))+,".8'0"39>';26"*+'39"3 )%+5'2,-)*#)'39"3',)."7-)'21'39)'#$*37"('&*27%+'"3'39)'$%#)*3$%&'$%073'3)*/$%"('21'39)'20'"/05'?Q'"%+%?T "*)'$%')11).3'$%'0"*"(()(>';97-5',4'/"8$%&'?T'(26)*'39"%'?Q',45'-"45'"'1".32*'@'<$>)>5''69)*)'@'>'C=5'?T'$12*.)+'32'."**4'"'.7**)%3'@B3$/)-'39"3'$%'?Q>';97-5'69$()')Q'=')C5')T ='@)C%"%+')U'='<@'+'C=)C>'A3'$-'39)'.7**)%3 /7(3$0($."3$2%',4'"'1".32*'21'<@'+'C='39"3')%",()-'"'("*&)'#2(3"&)'+*20'32'+)#)(20'".*2--'?U'"%+'9)%.)'" ("*&)'vB'6$39273'7-$%&'"'("*&)'#"(7)'12*'?U>'P23$.)'"(-2'39"3'39)'.7**)%3'39*27&9'?U'$-'$%+)0)%+)%3'21'39) #"(7)'21'?U>'A3'12((26-'39"3'39)'.$*.7$3'."%',)'7-)+'"-'"'.7**)%3'"/0($1$)*'"-'-926%'$%'S$&>'Q>D>' i2 % iI
i4
R2
R4
R3 v1 % 0 iI
R2 i3 % i R3 I ! "
"
i4 % 1 "
#
R2 i R3 I
Figure 2.9 H'.7**)%3'"/0($1$)*',"-)+'2%'39) .$*.7$3' 21' S$&>' Q>c>' ;9)' "/0($1$)*' +)($#)*-' $3273073' .7**)%3' 32' ?U>' A3' 9"-' "' .7**)%3' &"$%' 21';9)'(2"+')>5'%)$39)*'21'$3-'362'3)*/$B %"(-'."%',)'.2%%).3)+'32'&*27%+=>
2.2 The Inverting Configuration
EXERCISES D2.4' a-)'39)'.$*.7$3'21'S$&>'Q>V'32'+)-$&%'"%'$%#)*3$%&'"/0($1$)*'9"#$%&'"'&"$%'21'−CF'"%+'"%'$%073'*)-$-3B "%.)'21'CFF'8Ω>'i$#)'39)'#"(7)-'21'?C%"%+'?Q> Ans. ?C'='CFF'8ΩX'?Q'Z'C'RΩ 2.5' ;9)'.$*.7$3'-926%'$%'S$&>'@Q>V<"='."%',)'7-)+'32'$/0()/)%3'"'3*"%-*)-$-3"%.)'"/0($1$)*'<-))';",() C>C'$%'L).3$2%'C>V=>'S$%+'39)'#"(7)'21'39)'$%073'*)-$-3"%.)'?)5'39)'3*"%-*)-$-3"%.)'?-5'"%+'39)'273073 *)-$-3"%.)'?1'21'39)'3*"%-*)-$-3"%.)'"/0($1$)*>'A1'39)'-$&%"('-27*.)'-926%'$%'S$&>'@Q>V<,='$-'.2%%).3)+ 32'39)'$%073'21'39)'3*"%-*)-$-3"%.)'"/0($1$)*5'1$%+'$3-'273073'#2(3"&)> Ans. ?)'='FX'?-'= −CF'8ΩX'?1'='FX'vB'Z'−V'`
Figure E2.5
2.6' S2*'39)'.$*.7$3'$%'S$&>'@Q>E'+)3)*/$%)'39)'#"(7)-'21'vC5')C5')Q5'vB5')D5'"%+')B>'H(-2'+)3)*/$%)'39)'#2(3"&) &"$%' v B ⁄ v > 5 '.7**)%3'&"$%' ) D ⁄ ) > 5 '"%+'026)*'&"$%' E B ⁄ E > > Ans. F'`X'C'/HX'C'/HX'−CF'`X'−CF'/HX'−CC'/HX'−CF'`d`'
1 k& v1
1V
" !
10 k&
! "
iO iL
vO
1 k&
Figure E2.6
2.2.4 An Important Application—The Weighted Summer H'#)*4'$/02*3"%3'"00($."3$2%'21'39)'$%#)*3$%&'.2%1$&7*"3$2%'$-'39)'6)$&93)+B-7//)*'.$*B .7$3'-926%'$%'S$&>'Q>CF>'!)*)'6)'9"#)'"'*)-$-3"%.)'?2'$%'39)'%)&"3$#)B1))+,".8'0"39'<",)12*)=X',73'6)'9"#)'"'%7/,)*'21'$%073'-$&%"(-'vC5'vQ5'>'>'>'5' v*')".9'"00($)+'32'"'.2**)B -02%+$%&'*)-$-32*'?C5'?Q5'>'>'>'5'?*5'69$.9'"*)'.2%%).3)+'32'39)'$%#)*3$%&'3)*/$%"('21'39)'20 "/0>'S*2/'27*'0*)#$27-'+$-.7--$2%5'39)'$+)"('20'"/0'6$(('9"#)'"'#$*37"('&*27%+'"00)"*$%&
65
66 Chapter 2 Operational Amplifiers "3' $3-' %)&"3$#)' $%073' 3)*/$%"(>' ?9/J-' ("6' 39)%' 3)((-' 7-' 39"3' 39)' .7**)%3-' )C5' )Q5' >' >' >' 5' )*' "*) &$#)% ,4
v ) Q = BBBBQB, ?Q
v ) C = BBBBCB, ?C
>'>'>',
v ) * = BBBB*B ?*
0
Figure 2.10 H'6)$&93)+'-7//)*>
H(('39)-)'.7**)%3-'-7/'32&)39)*'32'0*2+7.)'39)'.7**)%3')X'39"3'$-5
) = )C + )Q + … + )*
E=
6$((',)'12*.)+'32'1(26'39*27&9'?2'<-$%.)'%2'.7**)%3'1(26-'$%32'39)'$%073'3)*/$%"(-'21'"%'$+)"('20 "/0=>';9)'273073'#2(3"&)'vB'/"4'%26',)'+)3)*/$%)+',4'"%239)*'"00($."3$2%'21'?9/J-'("65
v B = F ! )? 2 = ! )? 2 ;97-5
?2 ?2 ?2 v B = ! ' BBBBB v C + BBBBB v Q + … + BBBBB v * ' ?C ?Q ?*
'I=
;9"3'$-5'39)'273073'#2(3"&)'$-'"'6)$&93)+'-7/'21'39)'$%073'-$&%"(-'vC5'vQ5'>'>'>'5'v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
? v B = v C BBBBB/ ?C
? ? BBBBB0 + v Q BBBBB/ ?5 ?Q
? ? ? BBBBB0 ! v T BBBBB0 ! v U BBBBB0 ?5 ?T ?U
'''' ''
c=
2.3 The Noninverting Configuration
Rc
Ra
v1 v2
R1 !
Rb
"
R3
!
R2
v3
vO
"
R4
v4
Figure 2.11 H'6)$&93)+'-7//)*'."0",()'21'$/0()/)%3$%&'-7//$%&'.2)11$.$)%3-'21',239'-$&%->
EXERCISES D2.7' j)-$&%' "%' $%#)*3$%&' 20B"/0' .$*.7$3' 32' 12*/' 39)' 6)$&93)+' -7/' vB' 21' 362' $%073-' vC' "%+' vQ>' A3' $*)K7$*)+'39"3'vB'= −'G922-)'#"(7)-'12*'?C5'?Q5'"%+'?2''-2'39"3'12*'"'/"M$/7/'273073'#2(3B "&)'21'CF'`'39)'.7**)%3'$%'39)'1))+,".8'*)-$-32*'6$(('%23')M.))+'C'/H> Ans. H'02--$,()'.92$.):'?C'='CF'8Ω5'?Q'='Q'8Ω5'"%+'?2''='CF'8Ω D2.8' a-)'39)'$+)"'0*)-)%3)+'$%'S$&>'Q>CC'32'+)-$&%'"'6)$&93)+'-7//)*'39"3'0*2#$+)v B = Qv C + v Q ! Uv T Ans. H'02--$,()'.92$.):'?C'='V'8Ω5'?Q'='CF'8Ω5'?/%='CF'8Ω5'?5'='CF'8Ω5'?T'='Q>V'8Ω5 ?0'='CF'8Ω>''
2.3 The Noninverting Configuration ;9)'-).2%+'.(2-)+B(220'.2%1$&7*"3$2%'6)'-9"(('-37+4'$-'-926%'$%'S$&>'Q>CQ>'!)*)'39)'$%073 -$&%"('v>'$-'"00($)+'+$*).3(4'32'39)'02-$3$#)'$%073'3)*/$%"('21'39)'20'"/0'69$()'2%)'3)*/$%"('21 ?C'$-'.2%%).3)+'32'&*27%+>''
2.3.1 The Closed-Loop Gain H%"(4-$-'21'39)'%2%$%#)*3$%&'.$*.7$3'32'+)3)*/$%)'$3-'.(2-)+B(220'&"$%' ( v B ⁄ v > ) '$-'$((7-3*"3)+ $%' S$&>' Q>CT>' H&"$%' 39)' 2*+)*' 21' 39)' -3)0-' $%' 39)' "%"(4-$-' $-' $%+$."3)+' ,4' .$*.()+' %7/,)*-> H--7/$%&'39"3'39)'20'"/0'$-'$+)"('6$39'$%1$%$3)'&"$%5'"'#$*37"('-92*3'.$*.7$3')M$-3-',)36))%'$3362'$%073'3)*/$%"(->'!)%.)'39)'+$11)*)%.)'$%073'-$&%"('$-
v v >. = BBBBBB = F $
12*'$ = ∞ '
;97-'39)'#2(3"&)'"3'39)'$%#)*3$%&'$%073'3)*/$%"('6$((',)')K7"('32'39"3'"3'39)'%2%$%#)*3$%&'$%073 3)*/$%"(5'69$.9'$-'39)'"00($)+'#2(3"&)'v>>';9)'.7**)%3'39*27&9'?C'."%'39)%',)'+)3)*/$%)+'"v > ⁄ ? C>'e)."7-)'21'39)'$%1$%$3)'$%073'$/0)+"%.)'21'39)'20'"/05'39$-'.7**)%3'6$(('1(26'39*27&9 ?Q5'"-'-926%'$%'S$&>'Q>CT>'P26'39)'273073'#2(3"&)'."%',)'+)3)*/$%)+'1*2/
v v B = v > + BBBBB> ? Q ?C
67
68 Chapter 2 Operational Amplifiers
Figure 2.12 ;9)'%2%$%#)*3$%&'.2%1$&7*"3$2%>
5 3
vI R1
vI R1
2v I
R1
! 0 1 vId % 0 V 4 " " vI !
R2 vO % vI "
!
"
R vI R % vI 1 " 2 R1 2 R1
6
" vO !
Figure 2.13 H%"(4-$-'21'39)'%2%$%#)*3$%&'.$*.7$3>';9)'-)K7)%.)'21'39)'-3)0-'$%'39)'"%"(4-$-'$-'$%+$."3)+',4' 39)'.$*.()+'%7/,)*->
69$.9'4$)(+-
vB ? BBBBB = C + BBBBBQ ' v> ?C
D=
S7*39)*'$%-$&93'$%32'39)'20)*"3$2%'21'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%'."%',)'2,3"$%)+',4 .2%-$+)*$%&'39)'12((26$%&:'L$%.)'39)'.7**)%3'$%32'39)'20B"/0'$%#)*3$%&'$%073'$-'[)*25'39)'.$*B .7$3'.2/02-)+'21'?C'"%+'?Q'".3-'$%')11).3'"-'"'#2(3"&)'+$#$+)*'1))+$%&'"'1*".3$2%'21'39)'273073 #2(3"&)',".8'32'39)'$%#)*3$%&'$%073'3)*/$%"('21'39)'20'"/0X'39"3'$-5
?C B v C = v B BBBBBBBBBBBBBBBB ?C + ?Q
'CF=
;9)%'39)'$%1$%$3)'20B"/0'&"$%'"%+'39)'*)-7(3$%&'#$*37"('-92*3'.$*.7$3',)36))%'39)'362'$%073'3)*/$B %"(-'21'39)'20'"/0'12*.)-'39$-'#2(3"&)'32',)')K7"('32'39"3'"00($)+'"3'39)'02-$3$#)'$%073'3)*/$%"(X'397-5
?C v B BBBBBBBBBBBBBBBBB ?C + ?Q
= v>
69$.9'4$)(+-'39)'&"$%')M0*)--$2%'&$#)%'$%'@K>'D=> ;9$-'$-'"%'"00*20*$"3)'02$%3'32'*)1().3'17*39)*'2%'39)'".3$2%'21'39)'%)&"3$#)'1))+,".8'0*)-)%3 $%' 39)' %2%$%#)*3$%&' .$*.7$3' 21' S$&>' Q>CQ>' k)3' v>' $%.*)"-)>' L7.9' "' .9"%&)' $%' v>' 6$((' ."7-)' v>.' 32 $%.*)"-)5'"%+'vB'6$(('.2**)-02%+$%&(4'$%.*)"-)'"-'"'*)-7(3'21'39)'9$&9'<$+)"((4'$%1$%$3)='&"$%'21'39) 20'"/0>'!26)#)*5'"'1*".3$2%'21'39)'$%.*)"-)'$%'vB%6$((',)'1)+',".8'32'39)'$%#)*3$%&'$%073'3)*/$%"( 21'39)'20'"/0'39*27&9'39)'';9)'*)-7(3'21'39$-'1))+,".8'6$((',)'32'.27%3)*B ".3'39)'$%.*)"-)'$%'v>. 5'+*$#$%&'v>.',".8'32'[)*25'"(,)$3'"3'"'9$&9)*'#"(7)'21'vB'39"3'.2**)-02%+-'32 39)'$%.*)"-)+'#"(7)'21'v> >';9$-'.(<(*(8/&);('".3$2%'21'%)&"3$#)'1))+,".8'&$#)-'$3'39)'"(3)*%"3$#) %"/)'1$'$"$%,&!#$*3$$15,06>'S$%"((45'%23)'39"3'39)'"*&7/)%3'",2#)'"00($)-')K7"((4'6)(('$1'v> +).*)"-)->'H'12*/"('"%+'+)3"$()+'-37+4'21'1))+,".8'$-'0*)-)%3)+'$%'G9"03)*'CF>'
2.3 The Noninverting Configuration
2.3.2 Effect of Finite Open-Loop Gain H-'6)'9"#)'+2%)'12*'39)'$%#)*3$%&'.2%1$&7*"3$2%5'6)'%26'.2%-$+)*'39)')11).3'21'39)'1$%$3) 20B"/0'20)%B(220'&"$%'$'2%'39)'&"$%'21'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%>'H--7/$%&'39)'20'"/0 32',)'$+)"(')M.)03'12*'9"#$%&'"'1$%$3)'20)%B(220'&"$%'$5'$3'."%',)'-926%'39"3'39)'.(2-)+B(220 &"$%'21'39)'%2%$%#)*3$%&'"/0($1$)*'.$*.7$3'21'S$&>'Q>CQ'$-'&$#)%',4
v C 2 ( ?Q ⁄ ?C ) A ≡ BBBBBB 3 BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B v> C 2 ( ?Q ⁄ ?C ) C 2 BBBBBBBBBBBBBBBBBBBBBBBBBBBBB $
"#$%%&
?,-)*#)'39"3'39)'+)%2/$%"32*'$-'$+)%3$."('32'39"3'12*'39)'."-)'21'39)'$%#)*3$%&'.2%1$&7*"3$2% <@K>'Q>V=>';9$-'$-'%2'.2$%.$+)%.)X'$3'$-'"'*)-7(3'21'39)'1".3'39"3',239'39)'$%#)*3$%&'"%+'39)'%2%B $%#)*3$%&'.2%1$&7*"3$2%-'9"#)'39)'-"/)'1))+,".8'(2205'69$.9'."%',)'*)"+$(4'-))%'$1'39)'$%073 -$&%"('-27*.)'$-')($/$%"3)+'<$>)>5'-92*3B.$*.7$3)+=>';9)'%7/)*"32*-5'926)#)*5'"*)'+$11)*)%35'12* 39)'%7/)*"32*'&$#)-'39)'$+)"('2*'%2/$%"('.(2-)+B(220'&"$%'< ! ? Q ⁄ ? C '12*'39)'$%#)*3$%&'.2%B 1$&7*"3$2%5'"%+' C 2 ? Q ⁄ ? C 12*'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%=>'S$%"((45'6)'%23)'<6$39'*)"-B -7*"%.)='39"3'39)'&"$%')M0*)--$2%'$%'@K>'CC='*)+7.)-'32'39)'$+)"('#"(7)'12*'$'='∞>'A%'1".35'$3 "00*2M$/"3)-'39)'$+)"('#"(7)'12*
?Q l C 2 BBBBB $> l ?C ;9$-'$-'39)'-"/)'.2%+$3$2%'"-'$%'39)'$%#)*3$%&'.2%1$&7*"3$2%5')M.)03'39"3'9)*)'39)'K7"%3$34'2% 39)'*$&93B9"%+'-$+)'$-'39)'%2/$%"('.(2-)+B(220'&"$%>;9)')M0*)--$2%-'12*'39)'".37"('"%+'$+)"( #"(7)-'21'39)'.(2-)+B(220'&"$%'A'$%'@K->'CC='"%+'D=5'*)-0).3$#)(45'."%',)'7-)+'32'+)3)*B /$%)'39)'0)*.)%3"&)')**2*'$%'A'*)-7(3$%&'1*2/'39)'1$%$3)'20B"/0'&"$%'$'"C 2 ( ?Q ⁄ ?C ) B × CFF '()*(+,-./0+-())1)- 3 ! BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB $ 2 C 2 ( ?Q ⁄ ?C )
"#$%#&
;97-5'"-'"%')M"/0()5'$1'"%'20'"/0'6$39'"%'20)%B(220'&"$%'21'CFFF'$-'7-)+'32'+)-$&%'"'%2%$%B #)*3$%&'"/0($1$)*'6$39'"'%2/$%"('.(2-)+B(220'&"$%'21'CF5'6)'627(+')M0).3'39)'.(2-)+B(220 &"$%'32',)'",273'Cg',)(26'39)'%2/$%"('#"(7)>
2.3.3 Input and Output Resistance ;9)'&"$%'21'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%'$-'02-$3$#)f9)%.)'39)'%"/)'*1*)*;(8&)*<>';9) $%073'$/0)+"%.)'21'39$-'.(2-)+B(220'"/0($1$)*'$-'$+)"((4'$%1$%$3)5'-$%.)'%2'.7**)%3'1(26-'$%32 39)'02-$3$#)'$%073'3)*/$%"('21'39)'20'"/0>';9)'273073'21'39)'%2%$%#)*3$%&'"/0($1$)*'$-'3"8)% "3'39)'3)*/$%"(-'21'39)'$+)"('#2(3"&)'-27*.)'$'Q>T=5'397-'39)'273073'*)-$-3"%.)'21'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%'$-'[)*2>
2.3.4 The Voltage Follower ;9)'0*20)*34'21'9$&9'$%073'$/0)+"%.)'$-'"'#)*4'+)-$*",()'1)"37*)'21'39)'%2%$%#)*3$%&'.2%1$&7*"B 3$2%>'A3')%",()-'7-$%&'39$-'.$*.7$3'"-'"',711)*'"/0($1$)*'32'.2%%).3'"'-27*.)'6$39'"'9$&9'$/0)+B "%.)'32'"'(26B$/0)+"%.)'(2"+>'Y)'9"#)'+$-.7--)+'39)'%))+'12*',711)*'"/0($1$)*-'$%'L).3$2%'C>V> A%'/"%4'"00($."3$2%-'39)',711)*'"/0($1$)*'$-'%23'*)K7$*)+'32'0*2#$+)'"%4'#2(3"&)'&"$%X'*"39)*5'$3 $-'7-)+'/"$%(4'"-'"%'$/0)+"%.)'3*"%-12*/)*'2*'"'026)*'"/0($1$)*>'A%'-7.9'."-)-'6)'/"4'/"8) ?Q'='F'"%+'?C'='∞'32'2,3"$%'39)')"!&9/',!"*,+(-!3!$%'-926%'$%'S$&> Q>CU<"=>';9$-'.$*.7$3'$.2//2%(4'*)1)**)+'32'"-'"'#.-&,'$*3.--.8$%5'-$%.)'39)'273073'^12((26-_'39)'$%073>'A%'39)'$+)"( ."-)5'vB'= v> 5'?$%'='∞5'?273'='F5'"%+'39)'12((26)*'9"-'39)')K7$#"()%3'.$*.7$3'-926%'$%'S$&>'Q>CU<,=>'
69
70 Chapter 2 Operational Amplifiers
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Figure 2.14 :,;';9)'7%$34B&"$%',711)*'2*'12((26)*'"/0($1$)*>':5;'A3-')K7$#"()%3'.$*.7$3'/2+)(>
L$%.)'$%'39)'#2(3"&)B12((26)*'.$*.7$3'39)')%3$*)'273073'$-'1)+',".8'32'39)'$%#)*3$%&'$%0735 39)'.$*.7$3'$-'-"$+'32'9"#)'CFFg'%)&"3$#)'1))+,".8>';9)'$%1$%$3)'&"$%'21'39)'20'"/0'39)%'".332'/"8)'v>.'='F'"%+'9)%.)'vB'='v>>'?,-)*#)'39"3'39)'.$*.7$3'$-')()&"%3'$%'$3-'-$/0($.$34N' L$%.)'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%'9"-'"'&"$%'&*)"3)*'39"%'2*')K7"('32'7%$345'+)0)%+$%& 2%'39)'.92$.)'21' ? Q ⁄ ? C5'-2/)'0*)1)*'32'."(('$3'^"'12((26)*'6$39'&"$%>_'''
EXERCISES 2.9' a-)'39)'-70)*02-$3$2%'0*$%.$0()'32'1$%+'39)'273073'#2(3"&)'21'39)'.$*.7$3'-926%'$%'S$&>'@Q>D> Ans. vB'='EvC'+'UvQ
Figure E2.9
2.10' A1'$%'39)'.$*.7$3'21'S$&>'@Q>D'39)'CB8Ω'*)-$-32*'$-'+$-.2%%).3)+'1*2/'&*27%+'"%+'.2%%).3)+'32'"'39$*+ -$&%"('-27*.)'vT5'7-)'-70)*02-$3$2%'32'+)3)*/$%)'vB'$%'3)*/-'21'vC5'vQ5'"%+'vT> Ans. vB'='EvC'+'UvQ'−'DvT' D2.11 j)-$&%'"'%2%$%#)*3$%&'"/0($1$)*'6$39'"'&"$%'21'Q>'H3'39)'/"M$/7/'273073'#2(3"&)'21'CF'`'39)'.7*B *)%3'$%'39)'#2(3"&)'+$#$+)*'$-'32',)'CF'µH> Ans. ?C'='?Q'='F>V'RΩ 2.12' <"='L926'39"3'$1'39)'20'"/0'$%'39)'.$*.7$3'21'S$&>'Q>CQ'9"-'"'1$%$3)'20)%B(220'&"$%'$5'39)%'39)'.(2-)+B (220'&"$%'$-'&$#)%',4'@K>'CC=>'<,='S2*'?C'='C'8Ω'"%+'?Q'='D'8Ω'1$%+'39)'0)*.)%3"&)'+)#$"3$2%'ε 21'39)'.(2-)+B(220'&"$%'1*2/'39)'$+)"('#"(7)'21' ( C 2 ? Q ⁄ ? C ) '12*'39)'."-)-'$'='CFT5'CFU5'"%+'CFV> S2*'v>'='C'`5'1$%+'$%')".9'."-)'39)'#2(3"&)',)36))%'39)'362'$%073'3)*/$%"(-'21'39)'20'"/0> Ans. ε'='−Cg5'− F>Cg5 − F>FCgX'vQ'−'vC'='D>D'/`5'C'/`5'F>C'/`
2.4 Difference Amplifiers
2.13' S2*'39)'.$*.7$3'$%'S$&>'@Q>CT'1$%+'39)'#"(7)-'21')>5'vC5')C5')Q5'vB5%)D5'"%+')B>'H(-2'1$%+'39)'#2(3"&)'&"$% v B ⁄ v > 5 '39)'.7**)%3'&"$%' ) D ⁄ ) > 5 '"%+'39)'026)*'&"$%' E D ⁄ E > > Ans. FX'C'`X'C'/HX'C'/HX'CF'`X'CF'/HX'CC'/HX'CF'`d`'
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2.14' A3'$-'*)K7$*)+'32'.2%%).3'"'3*"%-+7.)*'9"#$%&'"%'20)%B.$*.7$3'#2(3"&)'21'C'`'"%+'"'-27*.)'*)-$-3"%.) 21'C RΩ'32'"'(2"+'21'CB8Ω'*)-$-3"%.)>'S$%+'39)'(2"+'#2(3"&)'$1'39)'.2%%).3$2%'$-'+2%)'<"='+$*).3(4'"%+ <,= 39*27&9'"'7%$34B&"$%'#2(3"&)'12((26)*> Ans. <"='C'/`X'<,='C'`
2.4 Difference Amplifiers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v>.'"%+'*)W).3 .2/0()3)(4'39)'.2//2%B/2+)'$%073'-$&%"('v>0-5'0*".3$."('.$*.7$3-'6$(('9"#)'"%'273073'#2(3"&) vB'&$#)%',4
v B = $ . v >. + $ 0- v >0-
CT=
69)*)'$.'+)%23)-'39)'"/0($1$)*'+$11)*)%3$"('&"$%'"%+'$0-'+)%23)-'$3-'.2//2%B/2+)'&"$%'<$+)B "((4'[)*2=>';9)')11$.".4'21'"'+$11)*)%3$"('"/0($1$)*'$-'/)"-7*)+',4'39)'+)&*))'21'$3-'*)W).3$2% 21'.2//2%B/2+)'-$&%"(-'$%'0*)1)*)%.)'32'+$11)*)%3$"('-$&%"(->';9$-'$-'7-7"((4'K7"%3$1$)+',4'" /)"-7*)'8%26%'"-'39)'0.++."/+.1$*%$2$0&!."*%,&!.*:<=>>;5'+)1$%)+'"-
$. B GROO = QF'(2& BBBBBBBBBBB $ 0Q
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;9)'3)*/-'.)22(8(*0('"%+'.)22(8(*&)/3'"*)'7-7"((4'7-)+'32'+)-.*$,)'-2/)69"3'+$11)*)%3'"/0($1$)*'340)->' S2*'27*'07*02-)-'"3'39$-'02$%35'39)'+$-3$%.3$2%'$-'%23'-711$.$)%3(4'-$&%$1$."%3>'Y)'6$((',)'/2*)'0*).$-)'%)"*' 39)')%+'21'39$-'-).3$2%>
71
72 Chapter 2 Operational Amplifiers vI1 % vIcm ! vId #2 ! "
vId #2 vId % vI2 ! vI1 1 2
vIcm % (vI1 " vI2) vIcm
" !
! "
vId #2 vI2 % vIcm " vId #2
Figure 2.15 O)0*)-)%3$%&'39)'$%073'-$&%"(-'32'" +$11)*)%3$"('"/0($1$)*' $%'3)*/-'21' 39)$*' +$11)*)%3$"( "%+'.2//2%B/2+)'.2/02%)%3->
;9)'%))+'12*'+$11)*)%.)'"/0($1$)*-'"*$-)-'1*)K7)%3(4'$%'39)'+)-$&%'21')().3*2%$.'-4-3)/-5')-0)B .$"((4'392-)')/0(24)+'$%'$%-3*7/)%3"3$2%>'H-'"'.2//2%')M"/0()5'.2%-$+)*'"'3*"%-+7.)*'0*2B #$+$%&' "'-/"(('<)>&>5'C'/`='-$&%"(' ,)36))%'$3-' 362'273073'3)*/$%"(-'69$()' )".9' 21'39)' 362 6$*)-'()"+$%&'1*2/' 39)'3*"%-+7.)*'3)*/$%"(-'32'39)'/)"-7*$%&'$%-3*7/)%3'/"4'9"#)'"'("*&) $%3)*1)*)%.)'-$&%"('<)>&>5'C'`='*)("3$#)'32'39)'.$*.7$3'&*27%+>';9)'$%-3*7/)%3'1*2%3')%+'2,#$B 27-(4'%))+-'"'+$11)*)%.)'"/0($1$)*> e)12*)'6)'0*2.))+'"%4'17*39)*'6)'-927(+'"++*)--'"'K7)-3$2%'39"3'39)'*)"+)*'/$&93'9"#): ;9)'20'"/0'$-'$3-)(1'"'+$11)*)%.)'"/0($1$)*X'694'%23'W7-3'7-)'"%'20'"/0\';9)'"%-6)*'$-'39"3 39)'#)*4'9$&9'<$+)"((4'$%1$%$3)='&"$%'21'39)'20'"/0'/"8)-'$3'$/02--$,()'32'7-)',4'$3-)(1>'O"39)*5 "-'6)'+$+',)12*)5'6)'9"#)'32'+)#$-)'"%'"00*20*$"3)'1))+,".8'%)362*8'32'.2%%).3'32'39)'20 "/0'32'.*)"3)'"'.$*.7$3'692-)'.(2-)+B(220'&"$%'$-'1$%$3)5'0*)+$.3",()5'"%+'-3",()>
2.4.1 A Single-Op-Amp Difference Amplifier ?7*'1$*-3'"33)/03'"3'+)-$&%$%&'"'+$11)*)%.)'"/0($1$)*'$-'/23$#"3)+',4'39)'2,-)*#"3$2%'39"3'39) &"$%'21'39)'%2%$%#)*3$%&'"/0($1$)*'.2%1$&7*"3$2%'$-'02-$3$#)5' ( C 2 ? Q ⁄ ? C )5 '69$()'39"3'21'39) $%#)*3$%&'.2%1$&7*"3$2%'$-'%)&"3$#)5'( ! ? Q ⁄ ? C )>'G2/,$%$%&'39)'362'.2%1$&7*"3$2%-'32&)39)*'$39)%'"'-3)0'$%'39)'*$&93'+$*).3$2%⎯%"/)(45'&)33$%&'39)'+$11)*)%.)',)36))%'362'$%073'-$&%"(-> ?1'.27*-)5'6)'9"#)'32'/"8)'39)'362'&"$%'/"&%$37+)-')K7"('$%'2*+)*'32'*)W).3'.2//2%B/2+) -$&%"(->' ;9$-5' 926)#)*5' ."%' ,)' )"-$(4' ".9$)#)+' ,4' "33)%7"3$%&' 39)' 02-$3$#)' $%073' -$&%"(' 32 *)+7.)'39)'&"$%'21'39)'02-$3$#)'0"39'1*2/' ( C 2 ? Q ⁄ ? C ) '32' ( ? Q ⁄ ? C ) >';9)'*)-7(3$%&'.$*.7$3 627(+'39)%'(228'($8)'39"3'-926%'$%'S$&>'Q>CE5'69)*)'39)'"33)%7"3$2%'$%'39)'02-$3$#)'$%073'0"39 $-'".9$)#)+',4'39)'#2(3"&)'+$#$+)*'';9)'0*20)*'*"3$2'21'39$-'#2(3"&)'+$#$+)*'."%',) +)3)*/$%)+'1*2/
?U ? ? BBBBBBBBBBBBBBBBB C + BBBBBQ = BBBBBQ ?U + ?T ?C ?C 69$.9'."%',)'073'$%'39)'12*/
?U ?Q BBBBBBBBBBBBBBBBB = BBBBBBBBBBBBBBBBB ?U + ?T ?Q + ?C ;9$-'.2%+$3$2%'$-'-"3$-1$)+',4'-)().3$%&
? ? BBBBBU = BBBBBQ ?T ?C
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Figure 2.16 H'+$11)*)%.)'"/0($1$)*>
;9$-'.2/0()3)-'27*'62*8>'!26)#)*5'6)'9"#)'0)*9"0-'0*2.))+)+'"'($33()'322'1"-3N'k)3J-'-3)0 ,".8'"%+'#)*$14'39"3'39)'.$*.7$3'$%'S$&>'Q>CE'6$39'?T'"%+'?U'-)().3)+'"..2*+$%&'32'@K>'CV= +2)-'$%'1".3'17%.3$2%'"-'"'+$11)*)%.)'"/0($1$)*>'L0).$1$."((45'6)'6$-9'32'+)3)*/$%)'39)'273073 #2(3"&)'vB'$%'3)*/-'21'v>C'"%+'v> Q>';26"*+'39"3')%+5'6)'2,-)*#)'39"3'39)'.$*.7$3'$-'($%)"*5'"%+ 397-'6)'."%'7-)'-70)*02-$3$2%> ;2' "00(4' -70)*02-$3$2%5' 6)' 1$*-3' *)+7.)' v> Q' 32' [)*2⎯39"3' $-5' &*27%+' 39)' 3)*/$%"(' 32 69$.9' v>Q' $-' "00($)+⎯"%+' 39)%' 1$%+' 39)' .2**)-02%+$%&' 273073' #2(3"&)5' 69$.9' 6$((' ,)' +7) )%3$*)(4'32'v>C>'Y)'+)%23)'39$-'273073'#2(3"&)'vBC>'A3-'#"(7)'/"4',)'127%+'1*2/'39)'.$*.7$3'$% S$&>'Q>CI<"=5'69$.9'6)'*).2&%$[)'"-'39"3'21'39)'$%#)*3$%&'.2%1$&7*"3$2%>';9)')M$-3)%.)'21'?T "%+'?U'+2)-'%23'"11).3'39)'&"$%')M0*)--$2%5'-$%.)'%2'.7**)%3'1(26-'39*27&9')$39)*'21'39)/> ;97-5
? v BC 3 ! BBBBBQ v >C ?C P)M35'6)'*)+7.)'v>C'32'[)*2'"%+')#"(7"3)'39)'.2**)-02%+$%&'273073'#2(3"&)'vBQ>';9)'.$*.7$3 6$(('%26'3"8)'39)'12*/'-926%'$%'S$&>'Q>CI<,=5'69$.9'6)'*).2&%$[)'"-'39)'%2%$%#)*3$%&'.2%B 1$&7*"3$2%'6$39'"%'"++$3$2%"('#2(3"&)'+$#$+)*5'/"+)'70'21'?T'"%+'?U5'.2%%).3)+'32'39)'$%073 v>Q>';9)'273073'#2(3"&)'vBQ'$-'39)*)12*)'&$#)%',4
?U ? ? B C + BBBBBQ = BBBBBQ v >Q v BQ = v >Q BBBBBBBBBBBBBBBB ?T + ?U ?C ?C 69)*)'6)'9"#)'73$($[)+'@K>'CV=> ;9)'-70)*02-$3$2%'0*$%.$0()'3)((-'7-'39"3'39)'273073'#2(3"&)'vB'$-')K7"('32'39)'-7/'21'vBC "%+'vBQ>';97-'6)'9"#)
? ?C
? ?C
'v B = BBBBBQ ( v >Q ! v >C )' = BBBBBQ v >. ''''
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? $ . = BBBBBQ ?C
CI=
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73
74 Chapter 2 Operational Amplifiers
vI1 vI 2
Figure 2.17 H00($."3$2%'21'-70)*02-$3$2%'32'39)'"%"(4-$-'21'39)'.$*.7$3'21'S$&>'Q>CE>
?T = ?C
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?U = ?Q
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?U C Bv ) C = BBBBB v >0- ! BBBBBBBBBBBBBBBB ? U + ? T >0?C ?T C BBBBB = v >0- BBBBBBBBBBBBBBBBB ?U + ?T ?C
Cc=
;9)'273073'#2(3"&)'."%'%26',)'127%+'1*2/'
?U Bv ! ) ? v B = BBBBBBBBBBBBBBBB ? U + ? T >0- Q Q L7,-3$373$%&')Q'=')C'"%+'12*')C'1*2/'@K>'Cc=5
? ? ? ?U + ?T ?C ?U + ?T ?U ?Q ?T = BBBBBBBBBBBBBBBBB C ! BBBBB ' BBBBB v >0?U + ?T ?C ?U
U T B v >0- ! BBBBBQ BBBBBBBBBBBBBBBB B v >0' v B = BBBBBBBBBBBBBBBB
;97-5
vB ?U ? ? B C ! BBBBBQ ' BBBBBT $ 0- ≡ BBBBBBBB = BBBBBBBBBBBBBBBB v >0?U + ?T ?C ?U
CD=
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2.4 Difference Amplifiers
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Figure 2.18 H%"(4-$-'21'39)'+$11)*)%.)'"/0($1$)*'32'+)3)*/$%)'$3-'.2//2%B/2+)'&"$%' $ 0- ≡ v B ⁄ v >0- > '
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?T = ?C
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?U = ?Q
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75
76 Chapter 2 Operational Amplifiers
EXERCISES 2.15 G2%-$+)*'39)'+$11)*)%.)B"/0($1$)*'.$*.7$3'21'S$&>'Q>CE'12*'39)'."-)'?C'='?T'='Q'8Ω'"%+'?Q'='?U'=
QFF 8Ω>'<"='S$%+'39)'#"(7)'21'39)'+$11)*)%3$"('&"$%'$.>'<,='S$%+'39)'#"(7)'21'39)'+$11)*)%3$"('$%073 *)-$-3"%.)'?).'"%+'39)'273073'*)-$-3"%.)'?1>'<.='A1'39)'*)-$-32*-'9"#)'Cg'32()*"%.)'<$>)>5')".9'."%',) 6$39$%'±Cg'21'$3-'%2/$%"('#"(7)=5'7-)'@K>'CD='32'1$%+'39)'62*-3B."-)'.2//2%B/2+)'&"$%'$0"%+'9)%.)'39)'.2**)-02%+$%&'#"(7)'21'GROO> Ans. <"='CFF'`d`'FU'`d`5'Ec'+e
D2.16 S$%+'#"(7)-'12*'39)'*)-$-3"%.)-'$%'39)'.$*.7$3'21'S$&>'Q>CE'-2'39"3'39)'.$*.7$3',)9"#)-'"-'"'+$11)*)%.)
"/0($1$)*'6$39'"%'$%073'*)-$-3"%.)'21'QF'8Ω'"%+'"'&"$%'21'CF> Ans. ?C'='?T'='CF'8ΩX'?Q'='?U'='CFF'8Ω
2.4.2 A Superior Circuit—The Instrumentation Amplifier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⁄ ? C )>'A3'12((26-'39"3')".9'21'v>C'"%+'v>Q'$-'"/0($1$)+',4 39$-'1".32*5'"%+'39)'*)-7(3$%&'"/0($1$)+'-$&%"(-'"00)"*'"3'39)'273073-'21'$C'"%+'$Q5'*)-0).3$#)(4> ;9)' +$11)*)%.)' "/0($1$)*' $%' 39)' -).2%+' -3"&)' 20)*"3)-' 2%' 39)' +$11)*)%.)' -$&%"( ( C + ? Q ⁄ ? C ) ( v >Q ! v >C ) =' ( C + ? Q ⁄ ? C )v >. '"%+'0*2#$+)-'"3'$3-'273073
? ? v B = BBBBBU C + BBBBBQ v >. ?T ?C ;97-'39)'+$11)*)%3$"('&"$%'*)"($[)+'$-
? ? $ . = BBBBBU C + BBBBBQ ?T ?C
QC=
77
78 Chapter 2 Operational Amplifiers ;9)'.2//2%B/2+)'&"$%'6$((',)'[)*2',)."7-)'21'39)'+$11)*)%.$%&'".3$2%'21'39)'-).2%+B-3"&) "/0($1$)*> ;9)'.$*.7$3'$%'S$&>'Q>QF<"='9"-'39)'"+#"%3"&)'21'#)*4'9$&9'<$+)"((4'$%1$%$3)='$%073'*)-$-B 3"%.)'"%+'9$&9'+$11)*)%3$"('&"$%>'H(-25'0*2#$+)+'$C'"%+'$Q'"%+'39)$*'.2**)-02%+$%&'*)-$-32*"*)'/"3.9)+5'39)'362'-$&%"('0"39-'"*)'-4//)3*$.⎯"'+)1$%$3)'"+#"%3"&)'$%'39)'+)-$&%'21'"'+$1B 1)*)%3$"('"/0($1$)*>';9)'.$*.7$35'926)#)*5'9"-'39*))'/"W2*'+$-"+#"%3"&)-: 1. ;9)'$%073'.2//2%B/2+)'-$&%"('v>0-'$-'"/0($1$)+'$%'39)'1$*-3'-3"&)',4'"'&"$%')K7"('32 39"3')M0)*$)%.)+',4'39)'+$11)*)%3$"('-$&%"('v>.>';9$-'$-'"'#)*4'-)*$27-'$--7)5'12*'$3'.27(+ *)-7(3'$%'39)'-$&%"(-'"3'39)'273073-'21'$C'"%+'$T',)$%&'21'-7.9'("*&)'/"&%$37+)-'39"3'39) 20'"/0-'-"37*"3)'2*)'2%'20B"/0'-"37*"3$2%'$%'L).3$2%'Q>c=>'e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m5'1*2/'&*27%+>';9)'.$*.7$3'6$39'39$-'-/"(( ,73'17%.3$2%"((4'0*2127%+'.9"%&)'$-'*)+*"6%'$%'S$&>'Q>QF<,=5'69)*)'6)'9"#)'(7/0)+'39)'362 *)-$-32*-' H%"(4-$-'21'39)'.$*.7$3'$%'S$&>'Q>QF<,=5'"--7/$%&'$+)"('20'"/0-5'$-'-3*"$&9312*6"*+5'"-'$$((7-3*"3)+'$%'S$&>'Q>QF<.=>';9)'8)4'02$%3'$-'39"3'39)'#$*37"('-92*3'.$*.7$3-'"3'39)'$%073-'21'20 "/0-'$C'"%+'$Q'."7-)'39)'$%073'#2(3"&)-'v>C'"%+'v>Q'32'"00)"*'"3'39)'362'3)*/$%"(-'21'*)-$-32*';97-'39)'+$11)*)%3$"('$%073'#2(3"&)'v>Q'−'v>C'≡'v>.'"00)"*-'".*2--'Q?C'"%+'."7-)-'"'.7**)%3 ) = v >. ⁄ Q? C%32'1(26'39*27&9'Q?C'"%+'39)'362'*)-$-32*-'(",)()+'?Q>';9$-'.7**)%3'$%'37*%'0*2B +7.)-'"'#2(3"&)'+$11)*)%.)',)36))%'39)'273073'3)*/$%"(-'21'$C'"%+'$Q'&$#)%',4
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v ? ? $ . ≡ BBBBBBB = BBBBBU C + BBBBBQB v >. ?T ?C
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;97-5 Q? C + BBBBBBBBQB = CFFF ? C2
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79
80 Chapter 2 Operational Amplifiers
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Example 2.4 S2*'39)'.$*.7$3'$%'S$&>'Q>QT5'+)*$#)'"%')M0*)--$2%'12*'39)'3*"%-1)*'17%.3$2%' !1 ( 4 ) ⁄ !) ( 4 )>'L926'39"3'39) 3*"%-1)*'17%.3$2%'$-'39"3'21'"'(26B0"--'L;G'.$*.7$3>'e4')M0*)--$%&'39)'3*"%-1)*'17%.3$2%'$%'39)'-3"%B +"*+'12*/'-926%'$%';",()'C>Q'2%'0"&)'TU5'1$%+'39)'+.'&"$%'"%+'39)'TB+e'1*)K7)%.4>'j)-$&%'39)'.$*.7$3 32'2,3"$%'"'+.'&"$%'21'UF'+e5'"'TB+e'1*)K7)%.4'21'C'8![5'"%+'"%'$%073'*)-$-3"%.)'21'C'8Ω>'H3'69"3'1*)B K7)%.4' +2)-' 39)' /"&%$37+)' 21' 3*"%-/$--$2%' ,).2/)' 7%$34\' Y9"3' $-' 39)' 09"-)' "%&()' "3' 39$1*)K7)%.4\
Figure 2.23 G$*.7$3'12*'@M"/0()'Q>U>
Solution ;2'2,3"$%'39)'3*"%-1)*'17%.3$2%'21'39)'.$*.7$3'$%'S$&>'Q>QT5'6)'-7,-3$373)'$%'@K>'QU=5'FC'='?C'"%+ F Q = ? Q || ( C ⁄ 4" Q )>'L$%.)'FQ'$-'39)'0"*"(()('.2%%).3$2%'21'362'.2/02%)%3-5'$3'$-'/2*)'.2%#)%$)%3'32 62*8'$%'3)*/-'21'HQX'39"3'$-5'6)'7-)'39)'12((26$%&'"(3)*%"3$#)'12*/'21'39)'3*"%-1)*'17%.3$2%: !1 ( 4 ) C BBBBBBBBBBBB B = ! BBBBBBBBBBBBBBBBBBBBBBBBB B !) ( 4 ) F C ( 4 )H Q ( 4 )
"%+'-7,-3$373)'FC'='?C'"%+' H Q ( 4 ) = ( C ⁄ ? Q ) + 4" Q '32'2,3"$% !1 ( 4 ) C B BBBBBBBBBBBB B = ! BBBBBBBBBBBBBBBBBBBBBBBBBB !) ( 4 ) ?C BBBBB + 4" Q ? C ?Q
;9$-'3*"%-1)*'17%.3$2%'$-'21'1$*-3'2*+)*5'9"-'"'1$%$3)'+.'&"$%' ( "3'4 = F, !1 ⁄ !) = ! ? Q ⁄ ? C )5'"%+'9"-'[)*2 &"$%'"3'$%1$%$3)'1*)K7)%.4>';97-'$3'$-'39)'3*"%-1)*'17%.3$2%'21'"'(26B0"--'L;G'%)362*8'"%+'."%',) )M0*)--)+'$%'39)'-3"%+"*+'12*/'21';",()'C>Q'"-'12((26-: !1 ( 4 ) ! ?Q ⁄ ?C BBBBBBBBBBBB B = BBBBBBBBBBBBBBBBBBBBBBB B !) ( 4 ) C + 4" Q ? Q
1*2/'69$.9'6)'1$%+'39)'+.'&"$%'I'32',) ? I = ! BBBBBQ ?C
81
82 Chapter 2 Operational Amplifiers
Example 2.4 continued
"%+'39)'TB+e'1*)K7)%.4'ω F'"C ω F = BBBBBBBBBBBB
"Q ?Q Y)'.27(+'9"#)'127%+'"(('39$-'1*2/'39)'.$*.7$3'$%'S$&>'Q>QT',4'$%-0).3$2%>'L0).$1$."((45'%23)'39"3'39) ."0".$32*' ,)9"#)-' "-' "%' 20)%' .$*.7$3' "3' +.X' 397-' "3' +.' 39)' &"$%' $-' -$/0(4' ( ! ? Q ⁄ ? C )>' S7*39)*/2*)5 ,)."7-)'39)*)'$-'"'#$*37"('&*27%+'"3'39)'$%#)*3$%&'$%073'3)*/$%"(5'39)'*)-$-3"%.)'-))%',4'39)'."0".$32* $-'?Q5'"%+'397-'39)'3$/)'.2%-3"%3'21'39)'L;G'%)362*8'$-'"Q?Q> P26'32'2,3"$%'"'+.'&"$%'21'UF'+e5'39"3'$-5'CFF'`d`5'6)'-)().3' ? Q ⁄ ? C = CFF> 'S2*'"%'$%073'*)-$-B 3"%.)'21'C'8Ω5'6)'-)().3'?C'='C'8Ω5'"%+'397-'?Q'='CFF'8Ω>'S$%"((45'12*'"'TB+e'1*)K7)%.4'2F'='C 8![5 6)'-)().3'"Q'1*2/ C T Q π × C × CF = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBTB " Q × CFF × CF
69$.9'4$)(+-'"Q'='C>VD'%S> ;9)'.$*.7$3'9"-'&"$%'"%+'09"-)'e2+)'0(23-'21'39)'-3"%+"*+'12*/'$%'S$&>'C>QT>'H-'39)'&"$%'1"((-'211'"3'39) *"3)' 21' nQF'+e/+)."+)5' $3' 6$(('*)".9' F' +e' $%'362' +)."+)-5' 39"3' $-5' "3'2' =' CFF2F' =' CFF' 8![>' H-' S$&> C>QT<,='$%+$."3)-5'"3'-7.9'"'1*)K7)%.4'69$.9'$-'/7.9'&*)"3)*'39"%'2F5'39)'09"-)'$-'"00*2M$/"3)(4'−DF°> ;2'39$-5'926)#)*5'6)'/7-3'"++'39)'CcF°'"*$-$%&'1*2/'39)'$%#)*3$%&'%"37*)'21'39)'"/0($1$)*'<$>)>5'39) %)&"3$#)'-$&%'$%'39)'3*"%-1)*'17%.3$2%')M0*)--$2%=>';97-'"3'CFF'8![5'39)'323"('09"-)'-9$13'6$((',)'−QIF° 2*5')K7$#"()%3(45'+DF°>
2.5.2 The Inverting Integrator e4'0(".$%&'"'."0".$32*'$%'39)'1))+,".8'0"39'<$>)>5'$%'0(".)'21'FQ'$%'S$&>'Q>QQ='"%+'"'*)-$-32*'"3 39)'$%073'<$%'0(".)'21'FC=5'6)'2,3"$%'39)'.$*.7$3'21'S$&>'Q>QU<"=>'Y)'-9"(('%26'-926'39"3'39$.$*.7$3' *)"($[)-' 39)' /"39)/"3$."(' 20)*"3$2%' 21' $%3)&*"3$2%>' k)3' 39)' $%073',)' "' 3$/)B#"*4$%& 17%.3$2%' v> <&=>' ;9)' #$*37"(' &*27%+' "3' 39)' $%#)*3$%&' 20B"/0' $%073' ."7-)-' v> <&=' 32' "00)"*' $% )11).3'".*2--'?5'"%+'397-'39)'.7**)%3')C<&='6$((',)' v > ( & ) ⁄ ?> ';9$-'.7**)%3'1(26-'39*27&9'39) ."0".$32*'"5'."7-$%&'.9"*&)'32'"..7/7("3)'2%'">'A1'6)'"--7/)'39"3'39)'.$*.7$3',)&$%-'20)*"B 3$2%' "3' 3$/)' &' =' F5' 39)%' "3' "%' "*,$3*"*4' 3$/)' &' 39)' .7**)%3' )C<&=' 6$((' 9"#)' +)02-$3)+' 2%' "' " & & .9"*&)')K7"('32' F ) C ( & ) .&> ';97-'39)'."0".$32*'#2(3"&)'v"<&='6$(('.9"%&)',4' BBB"CB F ) C ( & ) .&> 'A1 39)'$%$3$"('#2(3"&)'2%'"'<"3'&'='F='$-'+)%23)+'!" 5'39)%
C & v " ( & ) = !" + BBBB ) C ( & ) .& " F P26'39)'273073'#2(3"&)'vB<&='='−v"<&=X'397-5'
C v B ( & ) = ! BBBBBBBB "?
&
v > ( & ) .& ! !"
QV=
F
;97-'39)'.$*.7$3'0*2#$+)-'"%'273073'#2(3"&)'39"3'$-'0*202*3$2%"('32'39)'3$/)'$%3)&*"('21'39) $%0735'6$39'!"',)$%&'39)'$%$3$"('.2%+$3$2%'21'$%3)&*"3$2%'"%+'"?'39)'!"&$'%,&.%*&!+$*0."4&,"&> P23)'39"35'"-')M0).3)+5'39)*)'$-'"'%)&"3$#)'-$&%'"33".9)+'32'39)'273073'#2(3"&)5'"%+'397-'39$-
2.5 Integrators and Differentiators
" vC ! i1 i1 " vI (t)
R
0 0V
vO(t) % !
C ! " vO(t) !
"
!
1 CR
t
$ v (t) dt!V 0
I
C
Vo 1 %! Vi sCR
(a)
(b) Figure 2.24 :,;';9)'R$(()*'2*'$%#)*3$%&'$%3)&*"32*>':5;'S*)K7)%.4'*)-02%-)'21'39)'$%3)&*"32*>
$%3)&*"32*'.$*.7$3'$-'-"$+'32',)'"%'!"#$%&!"'*!"&$'%,&.%>'A3'$-'"(-2'8%26%'"-'"'=!--$%*!"&$'%,/ &.%'"13)*'"%')"*(4'62*8)*'$%'39$-'1$)(+> ;9)'20)*"3$2%'21'39)'$%3)&*"32*'.$*.7$3'."%',)'+)-.*$,)+'"(3)*%"3$#)(4'$%'39)'1*)K7)%.4 +2/"$%',4'-7,-3$373$%&'FC<4='='?'"%+' F Q ( 4 ) = C ⁄ 4" '$%'@K>'QU='32'2,3"$%'39)'3*"%-1)* 17%.3$2%
!1 ( 4 ) C BBBBBBBBBBBB B = ! BBBBBBBBBB !) ( 4 ) 4"?
QE=
!1 ( G ω ) C BBBBBBBBBBBBBBBBB B = ! BBBBBBBBBBBBBB !) ( G ω ) G ω "?
QI=
S2*'094-$."('1*)K7)%.$)-5'4'='Gω'"%+
;97-'39)'$%3)&*"32*'3*"%-1)*'17%.3$2%'9"-'/"&%$37+)
C !1 = BBBBBBBBBBB B BBBBB ω "? !)
Qc=
83
84 Chapter 2 Operational Amplifiers "%+'09"-)
φ = +DF°
QD=
;9)'e2+)'0(23'12*'39)'$%3)&*"32*'/"&%$37+)'*)-02%-)'."%',)'2,3"$%)+',4'%23$%&'1*2/'@K>'Qc= 39"3'"-' ω'+27,()-'<$%.*)"-)-',4'"%'2.3"#)='39)'/"&%$37+)'$-'9"(#)+'<+).*)"-)+',4'E'+e=> ;97-' 39)' e2+)' 0(23' $-' "' -3*"$&93' ($%)' 21' -(20)' nE' +e/2.3"#)' <2*5' )K7$#"()%3(45' nQF' +e/ +)."+)=>';9$-'($%)'<-926%'$%'S$&>'Q>QU,='$%3)*.)03-'39)'FB+e'($%)'"3'39)'1*)K7)%.4'39"3'/"8)!1 ⁄ !) = C5 '69$.9'1*2/'@K>'Qc='$-
C ω )*& = BBBBBBBB ' "?
TF=
;9)'1*)K7)%.4' ω)*&'$-'8%26%'"-'39)'!"&$'%,&.%*3%$?)$"09'"%+'$-'-$/0(4'39)'$%#)*-)'21'39) $%3)&*"32*'3$/)'.2%-3"%3> G2/0"*$-2%'21'39)'1*)K7)%.4'*)-02%-)'21'39)'$%3)&*"32*'32'39"3'21'"%'L;G'(26B0"--'%)3B 62*8'$%+$."3)-'39"3'39)'$%3)&*"32*',)9"#)-'"-'"'(26B0"--'1$(3)*'6$39'"'.2*%)*'1*)K7)%.4'21'[)*2> ?,-)*#)'"(-2'39"3'"3' ω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n?J d? *"39)*'39"%'$%1$%$3)>'L7.9'"'*)-$-32*'0*2#$+)-'"'+.'1))+,".8'0"39>'a%12*37%"3)(45'926)#)*5'39) $%3)&*"3$2%'$-'%2'(2%&)*'$+)"(5'"%+'39)'(26)*'39)'#"(7)'21'?J 5'39)'()--'$+)"('39)'$%3)&*"32*'.$*.7$3 ,).2/)->';9$-'$-',)."7-)'?J'."7-)-'39)'1*)K7)%.4'21'39)'$%3)&*"32*'02()'32'/2#)'1*2/'$3-'$+)"( (2."3$2%'"3'ω'='F'32'2%)'+)3)*/$%)+',4'39)'.2*%)*'1*)K7)%.4'21'39)'L;G'%)362*8''L0)B .$1$."((45'39)'$%3)&*"32*'3*"%-1)*'17%.3$2%',).2/)-
!1 ( 4 ) ?J ⁄ ? BBBBBBBBBBBB B = ! BBBBBBBBBBBBBBBBBBBBB B !) ( 4 ) C + 4"? J
RF C R ! " v I (t) !
"
" vO (t) !
Figure 2.25 ;9)'R$(()*'$%3)&*"32*'6$39'"'("*&)'*)-$-3"%.)'?J .2%%).3)+'$%'0"*"(()('6$39'"'$%'2*+)*'32'0*2#$+)'%)&"3$#)'1))+B ,".8'"%+'9)%.)'1$%$3)'&"$%'"3'+.>
2.5 Integrators and Differentiators
"-' 2002-)+' 32' 39)' $+)"(' 17%.3$2%' 21' ! C ⁄ 4"? >' ;9)' (26)*' 39)' #"(7)' 6)' -)().3' 12*' ?J 5' 39) 9$&9)*' 39)' .2*%)*' 1*)K7)%.4' ( C ⁄ "? J ) ' 6$((' ,)' "%+' 39)' /2*)' %2%$+)"(' 39)' $%3)&*"32* ,).2/)->' ;97-'-)().3$%&'"'#"(7)'12*'?J'0*)-)%3-'39)'+)-$&%)*'6$39'"'3*"+)B211',)36))%'+. 0)*12*/"%.)'"%+'-$&%"('0)*12*/"%.)>';9)')11).3'21'?J'2%'$%3)&*"32*'0)*12*/"%.)'$-'$%#)-3$B &"3)+'17*39)*'$%'39)'@M"/0()'Q>V>
Example 2.5 S$%+'39)'273073'0*2+7.)+',4'"'R$(()*'$%3)&*"32*'$%'*)-02%-)'32'"%'$%073'07(-)'21'CB`'9)$&93'"%+'CB/6$+39'oS$&>'Q>QE<"=p>'k)3'?'='CF'8Ω'"%+'"'='CF'%S>'A1'39)'$%3)&*"32*'."0".$32*'$-'-97%3)+',4'"'CBRΩ *)-$-32*5'926'6$(('39)'*)-02%-)',)'/2+$1$)+\';9)'20'"/0'$-'-0).$1$)+'32'-"37*"3)'"3'±CT'`> Solution A%'*)-02%-)'32'"'CB`5'CB/-'$%073'07(-)5'39)'$%3)&*"32*'273073'6$((',) & C v B ( & ) = ! BBBBBBBB C .&5 F ≤ & ≤ C'/- '''' "? F 69)*)'6)'9"#)'"--7/)+'39"3'39)'$%$3$"('#2(3"&)'2%'39)'$%3)&*"32*'."0".$32*'$-'F>'S2*'"'='CF'%S'"%+ ?'='CF'8Ω5'"?'='F>C'/-5'"%+ v B ( & ) = ! CF&5
F ≤ & ≤ C'/-
69$.9'$-'39)'($%)"*'*"/0'-926%'$%'S$&>'Q>QE<,=>'A3'*)".9)-'"'/"&%$37+)'21' −CF'`'"3'&'='C'/-'"%+ *)/"$%-'.2%-3"%3'39)*)"13)*> ;9"3'39)'273073'$-'"'($%)"*'*"/0'-927(+'"(-2',)'2,#$27-'1*2/'39)'1".3'39"3'39)'CB`'$%073'07(-) 0*2+7.)-'"'.2%-3"%3'.7**)%3'39*27&9'39)'."0".$32*'21' C'` ⁄ CF'8Ω = F>C'/H>';9$-'.2%-3"%3'.7**)%3 > ='F>C'/H'-700($)-'39)'."0".$32*'6$39'"'.9"*&)' >&5 "%+'397-'39)'."0".$32*'#2(3"&)'.9"%&)-'($%)"*(4 "-' ( >& ⁄ " )5 '*)-7(3$%&'$%' v B = ! ( > ⁄ " )& > 'A3'$-'62*39'*)/)/,)*$%&'39"3'.9"*&$%&'"'."0".$32*'6$39'" .2%-3"%3'.7**)%3'0*2+7.)-'"'($%)"*'#2(3"&)'".*2--'$3> P)M3'.2%-$+)*'39)'-$37"3$2%'6$39'*)-$-32*' ? J = C'RΩ '.2%%).3)+'".*2--'">'H-',)12*)5'39)'CB` 07(-)'6$(('0*2#$+)'"'.2%-3"%3'.7**)%3'>%='F>C'/H>'P265'926)#)*5'39$-'.7**)%3'$-'-700($)+'32'"%'L;G %)362*8'.2/02-)+'21'?J'$%'0"*"(()('6$39'">';97-5'39)'273073'6$((',)'"%')M02%)%3$"('9)"+$%&'326"*+ −CFF'`'6$39'"'3$/)'.2%-3"%3'21'"?J'= CF ' CF−D'' C ''CFE = CF'/-5 v B ( & ) = ! CFF ( C ! (
! & ⁄ CF
)5
F ≤ & ≤ C'/-
?1'.27*-)5'39)')M02%)%3$"('6$((',)'$%3)**703)+'"3'39)')%+'21'39)'07(-)5'39"3'$-5'"3'&%='C'/-5'"%+'39)'273B 073'6$(('*)".9'39)'#"(7) v B ( C'/- ) = ! CFF ( C ! (
! C ⁄ CF
) = ! D>V'`
;9)'273073'6"#)12*/'$-'-926%'$%'S$&>'Q>QE<.=5'1*2/'69$.9'6)'-))'39"3'$%.(7+$%&'?J'."7-)-'39)'*"/0'32 ,)'-($&93(4'*27%+)+'-7.9'39"3'39)'273073'*)".9)-'2%(4'−D>V'`5'F>V'`'-92*3'21'39)'$+)"('#"(7)'21'−CF'`> S7*39)*/2*)5'12*'&%>'C'/-5'39)'."0".$32*'+$-.9"*&)-'39*27&9'?J'6$39'39)'*)("3$#)(4'(2%&'3$/)B.2%-3"%3'21 CF'/->'S$%"((45'6)'%23)'39"3'20'"/0'-"37*"3$2%5'-0).$1$)+'32'2..7*'"3'±CT'`5'9"-'%2')11).3'2%'39)'20)*"B 3$2%'21'39$-'.$*.7$3>
85
86 Chapter 2 Operational Amplifiers >
Example 2.5 continued
vI (t)
1V 0 0
t
1 ms (a)
vO (t)
0
t
1 ms
!10 V (b) vO (t)
0
t
1 ms to 0 V
!9.5 V
Exponentials with time constant of 10 ms to !100 V (c)
Figure 2.26 Y"#)12*/-'12*'@M"/0()'Q>V:':,;'A%073'07(-)>':5;'?73073'($%)"*'*"/0'21'$+)"('$%3)&*"32*'6$39'3$/)'.2%B -3"%3'21'F>C'/->':0;'?73073')M02%)%3$"('*"/0'6$39'*)-$-32*'?J'.2%%).3)+'".*2--'$%3)&*"32*'."0".$32*>
;9)'0*).)+$%&')M"/0()'9$%3-'"3'"%'$/02*3"%3'"00($."3$2%'21'$%3)&*"32*-5'%"/)(45'39)$*'7-) $%' 0*2#$+$%&' 3*$"%&7("*' 6"#)12*/-' $%' *)-02%-)' 32' -K7"*)B6"#)' $%073->' ;9$-' "00($."3$2%' $)M0(2*)+'$%'@M)*.$-)'Q>Cc>'A%3)&*"32*-'9"#)'/"%4'239)*'"00($."3$2%-5'$%.(7+$%&'39)$*'7-)'$%'39) +)-$&%'21'1$(3)*-'
2.5 Integrators and Differentiators
2.5.3 The Op-Amp Differentiator A%3)*.9"%&$%&' 39)' (2."3$2%' 21' 39)' ."0".$32*' "%+' 39)' *)-$-32*' 21' 39)' $%3)&*"32*' .$*.7$3 *)-7(3-'$%'39)'.$*.7$3'$%'S$&>'Q>QI<"=5'69$.9'0)*12*/-'39)'/"39)/"3$."('17%.3$2%'21'+$11)*B )%3$"3$2%>';2'-))'926'39$-'.2/)-'",2735'()3'39)'$%073',)'39)'3$/)B#"*4$%&'17%.3$2%' v > ( & )5 "%+' %23)' 39"3' 39)' #$*37"(' &*27%+' "3' 39)' $%#)*3$%&' $%073' 3)*/$%"(' 21' 39)' 20' "/0' ."7-)v > ( & ) ' 32' "00)"*' $%' )11).3' ".*2--' 39)' ."0".$32*' ">' ;97-' 39)' .7**)%3' 39*27&9' "' 6$((' ,) " ( .v > ⁄ .& )5 ' "%+' 39$-' .7**)%3' 1(26-' 39*27&9' 39)' 1))+,".8' *)-$-32*' ?' 0*2#$+$%&' "3' 39) 20B"/0'273073'"'#2(3"&)' v B ( & )5
.v > ( & ) B v B ( & ) = ! "? BBBBBBBBBBBBB .&
TC=
;9)'1*)K7)%.4B+2/"$%'3*"%-1)*'17%.3$2%'21'39)'+$11)*)%3$"32*'.$*.7$3'."%',)'127%+',4'-7,-3$B 373$%&'$%'@K>'QU=5' F C ( 4 ) = C ⁄ 4" '"%+' F Q ( 4 ) = ? '32'2,3"
%$!1 ( 4 ) BBBBBBBBBBBB B = ! 4"? !) ( 4 )
TQ=
69$.9'12*'094-$."('1*)K7)%.$)-' 4 = G ω '4$)(+-
!1 ( G ω ) BBBBBBBBBBBBBBBBB B = ! G ω "? !) ( G ω ) i i
C
R
0
dvI (t) dt dv (t) vO (t) % !CR I dt Vo % !sCR Vi
i (t) % C
! " vI (t) !
TT=
" vO (t) !
" 0V (a)
Vo (dB) Vi
"6 dB/octave 0
( (log scale)
1 CR (b)
Figure 2.27 :,;*H'+$11)*)%3$"32*>':5;'S*)K7)%.4'*)-02%-)'21'"'+$11)*)%3$"32*'6$39'"'3$/)B.2%-3"%3'"?>'
87
88 Chapter 2 Operational Amplifiers ;97-'39)'3*"%-1)*'17%.3$2%'9"-'/"&%$37+)
!1 BBBBB = ω "? !)
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φ = ! DF°
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EXERCISES 2.22 G2%-$+)*'"%'$%#)*3$%&'"/0($1$)*'6$39'"'%2/$%"('&"$%'21'CFFF'.2%-3*7.3)+'1*2/'"%'20'"/0'6$39'"% $%073'211-)3'#2(3"&)'21'T'/`'"%+'6$39'273073'-"37*"3$2%'()#)(-'21'±CF'`>'<"='Y9"3'$-'<"00*2M$/"3)(4= 39)'0)"8'-$%)B6"#)'$%073'-$&%"('39"3'."%',)'"00($)+'6$39273'273073'.($00$%&\'<,='A1'39)')11).3'21'!BK $-'%7(()+'"3'*22/'3)/0)*"37*)'V'/` 2.23 G2%-$+)*'39)'-"/)'"/0($1$)*'"-'$%'@M)*.$-)'Q>QQf39"3'$-5'"%'$%#)*3$%&'"/0($1$)*'6$39'"'%2/$%"('&"$% 21'CFFF'.2%-3*7.3)+'1*2/'"%'20'"/0'6$39'"%'$%073'211-)3'#2(3"&)'21'T'/`'"%+'6$39'273073'-"37*"3$2% ()#)(-'21'±CF'`f)M.)03'9)*)'()3'39)'"/0($1$)*',)'."0".$3$#)(4'.270()+'"-'$%'S$&>'Q>TC<"=>'<"='Y9"3 $-'39)'+.'211-)3'#2(3"&)'"3'39)'2730735'"%+'69"3'<"00*2M$/"3)(4='$-'39)'0)"8'-$%)B6"#)'-$&%"('39"3'."% ,)'"00($)+'"3'39)'$%073'6$39273'273073'.($00$%&\'A-'39)*)'"'%))+'12*'211-)3'3*$//$%&\'<,='A1'?C'='C'8Ω "%+'?Q'='C RΩ5'1$%+'39)'#"(7)'21'39)'.270($%&'."0".$32*'"C'39"3'6$((')%-7*)'39"3'39)'&"$%'6$((',)'&*)"3)* 39"%'VI'+e'+26%'32'CFF'![> Ans. <"='T'/`5'CF'/`5'%2'%))+'12*'211-)3'3*$//$%&X'<,='C>E'µS
2.6 DC Imperfections
2.6.2 Input Bias and Offset Currents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
>LC + >LQ B >L = BBBBBBBBBBBBBBBBBB Q "%+'39)'+$11)*)%.)'$-'."(()+'39)'!"()&*.334$&*0)%%$"&'"%+'$-'&$#)%',4
>BK = >LC − >LQ ;40$."('#"(7)-'12*'&)%)*"(B07*02-)'20'"/0-'39"3'7-)',$02("*'3*"%-$-32*-'"*)'>L'= CFF'%H'"%+ >BK'= CF'%H> Y)' %26' 6$-9' 32' 1$%+' 39)' +.' 273073' #2(3"&)' 21' 39)' .(2-)+B(220' "/0($1$)*' +7)' 32' 39) $%073',$"-'.7**)%3->';2'+2'39$-'6)'&*27%+'39)'-$&%"('-27*.)'"%+'2,3"$%'39)'.$*.7$3'-926%'$% S$&> Q>TT'12*',239'39)'$%#)*3$%&'"%+'%2%$%#)*3$%&'.2%1$&7*"3$2%->'H-'-926%'$%'S$&>'Q>TT5'39) 273073'+.'#2(3"&)'$-'&$#)%',4
!B = >LC ? Q ! > L ? Q
TI=
;9$-'2,#$27-(4'0(".)-'"%'700)*'($/$3'2%'39)'#"(7)'21'?Q>'S2*37%"3)(45'926)#)*5'"'3).9%$K7) )M$-3-' 12*' *)+7.$%&' 39)' #"(7)' 21' 39)' 273073' +.' #2(3"&)' +7)' 32' 39)' $%073' ,$"-' .7**)%3->' ;9) /)392+'.2%-$-3-'21'$%3*2+7.$%&'"'*)-$-3"%.)'?T'$%'-)*$)-'6$39'39)'%2%$%#)*3$%&'$%073'()"+5'"-
Figure 2.32 ;9)'20B"/0'$%073',$"-'.7**)%3-' *)0*)-)%3)+',4'362'.7**)%3'-27*.)-'>LC'"%+'>LQ>
U
;9$-' $-' 39)' ."-)' 12*' 20' "/0-' .2%-3*7.3)+' 7-$%&' ,$02("*' W7%.3$2%' 3*"%-$-32*-'' ;92-)' 7-$%& R?LS@;-'$%'39)'1$*-3'<$%073='-3"&)'+2'%23'+*"6'"%'"00*).$",()'$%073',$"-'.7**)%3X'%)#)*39)()--5'39)'$%073 3)*/$%"(-'-927(+'9"#)'.2%3$%727-'+.'0"39-'32'&*27%+>'R2*)'2%'39$-'$%'("3)*'.9"03)*->
93
94 Chapter 2 Operational Amplifiers
Figure 2.33 H%"(4-$-'21'39)'.(2-)+B(220'"/0($1$)*5'3"8$%&'$%32'"..27%3'39)'$%073',$"-'.7**)%3->
Figure 2.34 O)+7.$%&'39)')11).3'21'39)'$%073',$"-'.7**)%3-',4'$%3*2+7.$%&'"'*)-$-32*'?T>
-926%'$%'S$&>'Q>TU>'S*2/'"'-$&%"('02$%3'21'#$)65'?T'9"-'"'%)&($&$,()')11).3'<$+)"((4'%2')11).3=> ;9)'"00*20*$"3)'#"(7)'12*'?T'."%',)'+)3)*/$%)+',4'"%"(4[$%&'39)'.$*.7$3'$%'S$&>'Q>TU5'69)*) "%"(4-$-'+)3"$(-'"*)'-926%5'"%+'39)'273073'#2(3"&)'$-'&$#)%',4
!B = − >LQ ? T + ? Q ( >LC ! >LQ ? T ⁄ ? C ) G2%-$+)*'1$*-3'39)'."-)'>LC'='>LQ'='>L5'69$.9'*)-7(3-'
%$!B = >L [ ? Q ! ? T ( C + ? Q ⁄ ? C ) ]
Tc=
2.6 DC Imperfections
;97-'6)'."%'*)+7.)'!B'32'[)*2',4'-)().3$%&'?T'-7.9'39"3
?Q ?C ?Q B ? T = BBBBBBBBBBBBBBBBBBBBBBBB = BBBBBBBBBBBBBBBB C + ?Q ⁄ ?C ?C + ?Q
TD=
;9"3'$-5'?T'-927(+',)'/"+)')K7"('32'39)'0"*"(()(')K7$#"()%3'21'?C'"%+'?Q>'' !"#$%&'-)().3)+'?T'"-'",2#)5'()3'7-')#"(7"3)'39)')11).3'21'"'1$%$3)'211-)3'.7**)%3'>BK>'k)3 >LC = >L + >BK ⁄ Q '"%+' >LQ = >L ! >BK ⁄ Q 5 '"%+'-7,-3$373)'$%'@K>'Tc=>';9)'*)-7(3'$-
!B = >BK ? Q
UF=
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a%12*37%"3)(45'$%.(7+$%&'?T'(26)*-'.2%-$+)*",(4'39)'$%073'*)-$-3"%.)'21'39)'.(2-)+B(220 "/0($1$)*>''
Figure 2.35 A%'"%'".B.270()+'"/0($1$)*'39)'+.'*)-$-3"%.)'-))%',4'39)'$%#)*3$%&'3)*/$%"('$-'?QX'9)%.) ?T'$-'.92-)%')K7"('32'?Q>
% R2
Figure 2.36 A((7-3*"3$%&'39)'%))+'12*'"'.2%3$%727-'+.'0"39'12*')".9'21'39)'20B"/0'$%073'3)*/$%"(->'L0).$1$B ."((45'%23)'39"3'39)'"/0($1$)*'6$(('*1&'62*8'6$39273'*)-$-32*'?T>
95
96 Chapter 2 Operational Amplifiers
EXERCISE 2.24 G2%-$+)*'"%'$%#)*3$%&'"/0($1$)*'.$*.7$3'+)-$&%)+'7-$%&'"%'20'"/0'"%+'362'*)-$-32*-5'?C'='CF'8Ω'"%+ ?Q ='C'RΩ>'A1'39)'20'"/0'$-'-0).$1$)+'32'9"#)'"%'$%073',$"-'.7**)%3'21'CFF'%H'"%+'"%'$%073'211-)3 .7**)%3'21'CF'%H5'1$%+'39)'273073'+.'211-)3'#2(3"&)'*)-7(3$%&'"%+'39)'#"(7)'21'"'*)-$-32*'?T'32',)'0(".)+ $%'-)*$)-'6$39'39)'02-$3$#)'$%073'()"+'$%'2*+)*'32'/$%$/$[)'39)'273073'211-)3'#2(3"&)>'Y9"3'$-'39)'%)6 #"(7)'21%!B\ Ans. F>C'`X'D>D'8Ω'FC'`
2.6.3 Effect of VOS and IOS on the Operation of the Inverting Integrator ?7*'+$-.7--$2%'21'39)'$%#)*3$%&'$%3)&*"32*'.$*.7$3'$%'L).3$2%'Q>V>Q'/)%3$2%)+'39)'-7-.)03$,$($34 21' 39$-' .$*.7$3' 32' -"37*"3$2%' $%' 39)' 0*)-)%.)' 21' -/"((' +.' #2(3"&)-' 2*' .7**)%3->' A3' ,)922#)-' 739)*)12*)'32'.2%-$+)*'39)')11).3'21'39)'20B"/0'+.'211-)3-'2%'$3-'20)*"3$2%>'H-'6$((',)'-))%5'39)-) )11).3-'."%',)'K7$3)'+*"/"3$.> ;2'-))'39)')11).3'21'39)'$%073'+.'211-)3'#2(3"&)'!BK 5'.2%-$+)*'39)'$%3)&*"32*'.$*.7$3'$%'S$&> Q>Tc5'69)*)'12*'-$/0($.$34'6)'9"#)'-92*3B.$*.7$3)+'39)'$%073'-$&%"('-27*.)>'H%"(4-$-'21'39) .$*.7$3'$-'-3*"$&9312*6"*+'"%+'$-'-926%'$%'S$&>'Q>TI>'H--7/$%&'12*'-$/0($.$34'39"3'"3'3$/)'&'='F 39)'#2(3"&)'".*2--'39)'."0".$32*'$-'[)*25'39)'273073'#2(3"&)'"-'"'17%.3$2%'21'3$/)'$-'&$#)%',4'''
!BK B &' v B = !BK + BBBBBBB "?
UC=
;97-'vB'$%.*)"-)-'($%)"*(4'6$39'3$/)'7%3$('39)'20'"/0'-"37*"3)-f.()"*(4'"%'7%"..)03",()'-$3B 7"3$2%N'H-'-927(+',)')M0).3)+5'39)'+.'$%073'211-)3'.7**)%3'>BK'0*2+7.)-'"'-$/$("*'0*2,()/> S$&7*)'Q>Tc'$((7-3*"3)-'39)'-$37"3$2%>'?,-)*#)'39"3'6)'9"#)'"++)+'"'*)-$-3"%.)'?'$%'39)'20B "/0'02-$3$#)B$%073'()"+'$%'2*+)*'32'8))0'39)'$%073',$"-'.7**)%3'>L'1*2/'1(26$%&'39*27&9'"> P)#)*39)()--5'39)'211-)3'.7**)%3'>BK'6$(('1(26'39*27&9'"'"%+'."7-)'vB'32'*"/0'($%)"*(4'6$39 3$/)'7%3$('39)'20'"/0'-"37*"3)-> H-'/)%3$2%)+'$%'L).3$2%'Q>V>Q'39)'+.'0*2,()/'21'39)'$%3)&*"32*'.$*.7$3'."%',)'"(()#$B "3)+',4'.2%%).3$%&'"'*)-$-32*'?J'".*2--'39)'$%3)&*"32*'."0".$32*'"5'"-'-926%'$%'S$&>'Q>QV>
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t
Figure 2.37 j)3)*/$%$%&'39)')11).3'21'39)'20B"/0'$%073'211-)3'#2("&)'!BK'2%'39)'R$(()*'$%3)&*"B 32*'.$*.7$3>'P23)'39"3'-$%.)'39)'273073'*$-)-'6$39'3$/)5'39)'20'"/0')#)%37"((4'-"37*"3)->
2.7 Effect of Finite Open-Loop Gain and Bandwidth on Circuit Performance
L7.9' "' *)-$-32*' 0*2#$+)-' "' +.' 0"39' 39*27&9' 69$.9' 39)' +.' .7**)%3-' BK' ."% 1(265' 6$39' 39)' *)-7(3' 39"3' vB' 6$((' %26' 9"#)' "' +.' .2/02%)%3' o!BK ( C + ? J ⁄ ? ) + > BK ? J p $%-3)"+'21'*$-$%&'($%)"*(4>';2'8))0'39)'+.'211-)3'"3'39)'273073'-/"((5'2%)'627(+'-)().3'" (26'#"(7)'12*'?J>'a%12*37%"3)(45'926)#)*5'39)'(26)*'39)'#"(7)'21'?J5'39)'()--'$+)"('39) $%3)&*"32*'.$*.7$3',).2/)->''' C
(IB1 ! IB2) % IOS IB2R#R % IB2
R
IB1 ! IB2
R !IB2R
"
vO vO % !IB2R "
Figure 2.38 @11).3'21'39)'20B"/0'
IOS $%073',$"-'"%+'211-)3'.7**)%3-'2%'39)' t C 0)*12*/"%.)'21'39)'R$(()*'$%3)&*"32*' .$*.7$3>
EXERCISE 2.25'G2%-$+)*'"'R$(()*'$%3)&*"32*'6$39'"'3$/)'.2%-3"%3'21'C'/-'"%+'"%'$%073'*)-$-3"%.)'21'CF'8Ω>'k)3'39) 20'"/0'9"#)'!BK'='Q'/`'"%+'273073'-"37*"3$2%'#2(3"&)-'21''±CQ'`>'<"='H--7/$%&'39"3'69)%'39) 026)*'-700(4'$-'37*%)+'2%'39)'."0".$32*'#2(3"&)'$-'[)*25'926'(2%&'+2)-'$3'3"8)'12*'39)'"/0($1$)*'32 -"37*"3)\'<,='L)().3'39)'("*&)-3'02--$,()'#"(7)'12*'"'1))+,".8'*)-$-32*'?J'-2'39"3'"3'()"-3'±10'`'21 273073' -$&%"(' -6$%&'*)/"$%-' "#"$(",()>' Y9"3'$-' 39)' .2*%)*' 1*)K7)%.4' 21' 39)'*)-7(3$%&' L;G'%)3B 62*8\ Ans. <"='E'-X'<,='CF'RΩ5'F>CE'!['
2.7 Effect of Finite Open-Loop Gain and Bandwidth on Circuit Performance 2.7.1 Frequency Dependence of the Open-Loop Gain ;9)'+$11)*)%3$"('20)%B(220'&"$%'$%21'"%'20'"/0'$-'%23'$%1$%$3)X'*"39)*5'$3'$-'1$%$3)'"%+'+).*)"-)6$39'1*)K7)%.4>'S$&7*)'Q>TD'-926-'"'0(23'12*' $ 5'6$39'39)'%7/,)*-'340$."('21'-2/)'.2//)*B .$"((4'"#"$(",()'&)%)*"(B07*02-)'20'"/0-'<-7.9'"-'39)'0207("*'IUCB340)'20'"/05'"#"$(",()'1*2/ /"%4'-)/$.2%+7.32*'/"%71".37*)*-X'$3-'$%3)*%"('.$*.7$3'$-'-37+$)+'$%'G9"03)*'CQ=> P23)'39"3'"(3927&9'39)'&"$%'$-'K7$3)'9$&9'"3'+.'"%+'(26'1*)K7)%.$)-5'$3'-3"*3-'32'1"(('211 "3'"'*"39)*'(26'1*)K7)%.4'';9)'7%$12*/'nQFB+ed+)."+)'&"$%'*2((211 -926%'$-'340$."('21'!"&$%",--9*0.+($"4,&$1'20'"/0->';9)-)'"*)'7%$3-'39"3'9"#)'"'%)362*8 <7-7"((4'"'-$%&()'."0".$32*='$%.(7+)+'6$39$%'39)'-"/)'AG'.9$0'692-)'17%.3$2%'$-'32'."7-) 39)' 20B"/0' &"$%'32' 9"#)'39)'-$%&()B3$/)B.2%-3"%3' ' ;9$-
97
98 Chapter 2 Operational Amplifiers
Figure 2.39 ?0)%B(220'&"$%'21'"'340$."('&)%)*"(B07*02-)'$%3)*%"((4'.2/0)%-"3)+'20'"/0>
0*2.)--' 21' /2+$14$%&' 39)' 20)%B(220' &"$%' $-' 3)*/)+' 3%$?)$"09* 0.+($"4,&!."5' "%+' $307*02-)'$-'32')%-7*)'39"3'20B"/0'.$*.7$3-'6$((' ,)'-3",()'<"-'2002-)+'32'2-.$(("32*4=>';9) -7,W).3'21'-3",$($34'21'20B"/0'.$*.7$3-f2*5'/2*)'&)%)*"((45'21'1))+,".8'"/0($1$)*-f6$(( ,)'-37+$)+'$%'G9"03)*'CF> e4' "%"(2&4' 32' 39)' *)-02%-)' 21' (26B0"--' L;G' .$*.7$3-' <-))' L).3$2%' C>E' "%+5' 12*' /2*) +)3"$(5'H00)%+$M'@=5'39)'&"$%'$<4='21'"%'$%3)*%"((4'.2/0)%-"3)+'20'"/0'/"4',)')M0*)--)+'"-
$F $ ( 4 ) = BBBBBBBBBBBBBBBBBBBBB C + 4 ⁄ ω5
UQ=
69$.9'12*'094-$."('1*)K7)%.$)-5'4'='Gω5',).2/)-
$F B $ ( G ω ) = BBBBBBBBBBBBBBBBBBBBBBBB C + G ω ⁄ ω5
UT=
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$F ω5 B $ ( G ω )'!' BBBBBBBBBBB Gω
UU=
$F ω5 B $ ( G ω ) ' = BBBBBBBBBBB
UV=
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2.7 Effect of Finite Open-Loop Gain and Bandwidth on Circuit Performance
L7,-3$373$%&'$%'@K>'UU='&$#)-
ω
$ ( G ω )'!' BBBBBB& Gω
UI=
;9)'1*)K7)%.4' 2 & = ω & ⁄ Q π '$-'7-7"((4'-0).$1$)+'2%'39)'+"3"'-9))3-'21'.2//)*.$"((4'"#"$(",() 20'"/0-'"%+'$-'8%26%'"-'39)')"!&9/',!"*5,"18!1&7>V'H(-2'%23)'39"3'12*' ω')' ω5'39)'20)%B (220'&"$%'$%'@K>'UQ=',).2/)-
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ω 2 $ ( G ω ) ! BBBBB& = BB& ω 2
UD=
;97-'$1'2&'$-'8%26%'' S7*39)*/2*)5' 2,-)*#)'39"3' 39$-' *)("3$2%-9$0' .2**)("3)6$39'39)'e2+)'0(23'$%'S$&>'Q>TD>'L0).$1$."((45'12*'2')'255%+27,($%&'2'<"%'2.3"#)'$%.*)"-)='*)-7(3$%' 9"(#$%&' 39)' &"$%' <"' EB+e' *)+7.3$2%=>' L$/$("*(45' $%.*)"-$%&% 2' ,4' "' 1".32*' 21' CF' <"' +)."+) $%.*)"-)='*)-7(3-'$%'*)+7.$%&'r$r',4'"'1".32*'21'CF' H-'"'/"33)*'21'0*".3$."('$/02*3"%.)5'6)'%23)'39"3'39)'0*2+7.3$2%'-0*)"+'$%'39)'#"(7)'21'2& ,)36))%'20B"/0'7%$3-'21'39)'-"/)'340)'$-'7-7"((4'/7.9'-/"(()*'39"%'39"3'2,-)*#)+'12*'$F'"%+ 25>'S2*'39$-'*)"-2%'2&'$-'0*)1)**)+'"-'"'-0).$1$."3$2%'0"*"/)3)*>'S$%"((45'$3'-927(+',)'/)%3$2%)+ 39"3' "%' 20' "/0' 9"#$%&' 39$-' 7%$12*/' nEB+ed2.3"#)' <2*' )K7$#"()%3(4' nQFB+ed+)."+)=' &"$% *2((211'$-'-"$+'32'9"#)'"'4!"'-$/(.-$*+.1$->'H(-25'-$%.)'39$-'-$%&()'02()'.1-)*/&(4'39)'"/0($B 1$)*'1*)K7)%.4'*)-02%-)5'$3'$-'."(()+'"'.1-)*/*&%+13(>*S2*'/2*)'2%'02()-'<"%+'[)*2-=5'39)'*)"+)* /"4'6$-9'32'.2%-7(3'H00)%+$M'S>
EXERCISE 2.26 H%'$%3)*%"((4'.2/0)%-"3)+'20'"/0'$-'-0).$1$)+'32'9"#)'"%'20)%B(220'+.'&"$%'21'CFE'+e'"%+'"'7%$34B &"$%',"%+6$+39'21'T'R![>'S$%+'25'"%+'39)'20)%B(220'&"$%'<$%'+e='"3'255'TFF'![5'T'8![5'CQ'8![5'"%+ EF'8![> Ans. CV'![X'CFT'+eX'cF'+eX'EF'+eX'Uc'+eX'TU'+e
2.7.2 Frequency Response of Closed-Loop Amplifiers Y)'%)M3'.2%-$+)*'39)')11).3'21'($/$3)+'20B"/0'&"$%'"%+',"%+6$+39'2%'39)'.(2-)+B(220'3*"%-1)* 17%.3$2%-'21'39)'362',"-$.'.2%1$&7*"3$2%-:'39)'$%#)*3$%&'.$*.7$3'21'S$&>'Q>V'"%+'39)'%2%$%#)*3$%& .$*.7$3'21'S$&>'Q>CQ>';9)'.(2-)+B(220'&"$%'21'39)'$%#)*3$%&'"/0($1$)*5'"--7/$%&'"'1$%$3)'20B"/0 20)%B(220'&"$%'$5'6"-'+)*$#)+'$%'L).3$2%'Q>Q'"%+'&$#)%'$%'@K>'V=5'69$.9'6)'*)0)"3'9)*)'"-
!1 !?Q ⁄ ?C BBBBB = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B C + ( C + ?Q ⁄ ?C ) ⁄ $ !)
VF=
L$%.)'2&'$-'39)'0*2+7.3'21'39)'+.'&"$%'$F'"%+'39)'TB+e',"%+6$+39'25'<69)*)'25 = ω5 /Qπ=5'$3'$-'"(-2'8%26% "-'39)'',!"@5,"18!1&7*(%.1)0&'';9)'*)"+)*'$-'."73$2%)+5'926)#)*5'39"3'$%'-2/)'"/0($1$)*-5'39) 7%$34B&"$%'1*)K7)%.4'"%+'39)'&"$%B,"%+6$+39'0*2+7.3'"*)'*1&')K7"(> V
99
100 Chapter 2 Operational Amplifiers L7,-3$373$%&'12*'$'1*2/'@K>'UQ='"%+'7-$%&'@K>'UE='&$#)-
!1 ( 4 ) !?Q ⁄ ?C BBBBBBBBBBBB B = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B !) ( 4 ) ?Q C 4 BBBB B BBBBB B BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B C+ C+ + ?C ω& ⁄ ( C + ?Q ⁄ ?C ) $F
VC=
l C + ? Q ⁄ ? C 5 '69$.9'$-'7-7"((4'39)'."-)5 S2*' $ F s l
!1 ( 4 ) !?Q ⁄ ?C BBBBBBBBBBBB B ≈ BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B !) ( 4 ) 4 C + BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB ω& ⁄ ( C + ?Q ⁄ ?C )
VQ=
69$.9'$-'21'39)'-"/)'12*/'"-'39"3'12*'"'(26B0"--'L;G'%)362*8'<-))';",()'C>Q5'0"&)'TU=>';9739)'$%#)*3$%&'"/0($1$)*'9"-'"%'L;G'(26B0"--'*)-02%-)'6$39'"'+.'&"$%'21'/"&%$37+)')K7"('32 ?Q /?C>';9)'.(2-)+B(220'&"$%'*2((-'211'"3'"'7%$12*/'nQFB+ed+)."+)'-(20)'6$39'"'.2*%)*'1*)B K7)%.4'
ω& ω T+e = BBBBBBBBBBBBBBBBBBBBBBBB C + ?Q ⁄ ?C
VT=
L$/$("*(45'"%"(4-$-'21'39)'%2%$%#)*3$%&'"/0($1$)*'21'S$&>'Q>CQ5'"--7/$%&'"'1$%$3)'20)%B(220 &"$%'$5'4$)(+-'39)'.(2-)+B(220'3*"%-1)*'17%.3$2%
!1 C + ?Q ⁄ ?C BBBBB = BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B !) C + ( C + ?Q ⁄ ?C ) ⁄ $
VU=
l C + ? Q ⁄ ? C'*)-7(3-'$% L7,-3$373$%&'12*'$'1*2/'@K>'UQ='"%+'/"8$%&'39)'"00*2M$/"3$2%' $ F s l
!1 ( 4 ) C + ?Q ⁄ ?C BBBBBBBBBBBB B ! BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB B !) ( 4 ) 4 C + BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB ω& ⁄ ( C + ?Q ⁄ ?C )
VV=
;97-'39)'%2%$%#)*3$%&'"/0($1$)*'9"-'"%'L;G'(26B0"--'*)-02%-)'6$39'"'+.'&"$%'21'( C + ? Q ⁄ ? C ) "%+'"'TB+e'1*)K7)%.4'&$#)%'"(-2',4'@K>'VT=>
Example 2.6 G2%-$+)*'"%'20'"/0'6$39'2& = C'R![>'S$%+'39)'TB+e'1*)K7)%.4'21'.(2-)+B(220'"/0($1$)*-'6$39'%2/$B %"(' &"$%-' 21' +CFFF5' +CFF5' +CF5' +C5' −C5' −CF5' −CFF5' "%+' −CFFF>' L8)3.9' 39)' /"&%$37+)' 1*)K7)%.4 *)-02%-)'12*'39)'"/0($1$)*-'6$39'.(2-)+B(220'&"$%-'21'+CF'"%+'nCF> Solution Y)'7-)'@K>'VT='32'2,3"$%'39)'*)-7(3-'&$#)%'$%'39)'12((26$%&'3",()> Closed-Loop Gain
+CFFF +CFF +CF +C −C −CF −CFF −CFFF
R2 ⁄ R1
'''''''''''''''''''DDD '''''''''''''DD D F C CF CFF CFFF
f3 dB = ft / (1 + R2 ⁄R1)
C'8![ CF'8![ CFF'8![ ''C'R![ F>V'R![ DF>D'8![ D>D'8![ !C'8![
2.7 Effect of Finite Open-Loop Gain and Bandwidth on Circuit Performance
S$&7*)'Q>UF'-926-'39)'1*)K7)%.4'*)-02%-)'12*'39)'"/0($1$)*'692-)'%2/$%"('+.'&"$%'$-'tCF'Q>UC'-926-'39)'1*)K7)%.4'*)-02%-)'12*'39)'nCF'<"(-2'QF'+e='."-)>'H%'$%3)*)-3B $%&'2,-)*#"3$2%'12((26-'1*2/'39)'3",()'",2#):';9)'7%$34B&"$%'$%#)*3$%&'"/0($1$)*'9"-'"'TB+e'1*)B K7)%.4'21'2& dQ'"-'.2/0"*)+'32'2&'12*'39)'7%$34B&"$%'%2%$%#)*3$%&'"/0($1$)*'<39)'7%$34B&"$%'#2(3"&) 12((26)*=>''''
Figure 2.40 S*)K7)%.4'*)-02%-)'21'"%'"/0($1$)*'6$39'"'%2/$%"('&"$%'21'+CF'`d`>
Figure 2.41 S*)K7)%.4'*)-02%-)'21'"%'"/0($1$)*'6$39'"'%2/$%"('&"$%'21'−CF'`d`>
;9)'3",()'$%'@M"/0()'Q>E'",2#)'.()"*(4'$((7-3*"3)-'39)'3*"+)B211',)36))%'&"$%'"%+',"%+B 6$+39:'S2*'"'&$#)%'20'"/05'39)'(26)*'39)'.(2-)+B(220'&"$%'*)K7$*)+5'39)'6$+)*'39)',"%+6$+39 ".9$)#)+>'A%+))+5'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%')M9$,$3-'"'.2%-3"%3'',!"@5,"18!1&7*(%.1)0& )K7"('32'2&'21'39)'20'"/0>'H%'$%3)*0*)3"3$2%'21'39)-)'*)-7(3-'$%'3)*/-'21'1))+,".8'39)2*4'6$((',) &$#)%'$%'G9"03)*'CF>
101
102 Chapter 2 Operational Amplifiers
EXERCISES 2.27 H%'$%3)*%"((4'.2/0)%-"3)+'20'"/0'9"-'"'+.'20)%B(220'&"$%'21'CFE'`d`'"%+'"%'".'20)%B(220'&"$%'21'UF +e'"3'CF'8![>'@-3$/"3)'$3-'TB+e'1*)K7)%.45'$3-'7%$34B&"$%'1*)K7)%.45'$3-'&"$%n,"%+6$+39'0*2+7.35 "%+'$3-')M0).3)+'&"$%'"3'C'8![> Ans. C'![X'C'R![X'C'R![X'EF'+e 2.28 H%'20'"/0'9"#$%&'"'CFEB+e'&"$%'"3'+.'"%+'"'-$%&()B02()'1*)K7)%.4'*)-02%-)'6$39'2&'Z'Q'R!['$7-)+'32'+)-$&%'"'%2%$%#)*3$%&'"/0($1$)*'6$39'%2/$%"('+.'&"$%'21'CFF>'S$%+'39)'TB+e'1*)K7)%.4'21 39)'.(2-)+B(220'&"$%> Ans. QF'8![
2.8 Large-Signal Operation of Op Amps A%'39$-'-).3$2%5'6)'-37+4'39)'($/$3"3$2%-'2%'39)'0)*12*/"%.)'21'20B"/0'.$*.7$3-'69)%'("*&) 273073'-$&%"(-'"*)'0*)-)%3>
2.8.1 Output Voltage Saturation L$/$("*'32'"(('239)*'"/0($1$)*-5'20'"/0-'20)*"3)'($%)"*(4'2#)*'"'($/$3)+'*"%&)'21'273073'#2(3B "&)->'L0).$1$."((45'39)'20B"/0'273073'-"37*"3)-'$%'39)'/"%%)*'-926%'$%'S$&>'C>CU'6$39'Dt'"%+ Dn'6$39$%'C'`'2*'-2'21'39)'02-$3$#)'"%+'%)&"3$#)'026)*'-700($)-5'*)-0).3$#)(4>';97-5'"%'20 "/0' 39"3' $-' 20)*"3$%&' 1*2/' ±CVB`' -700($)-' 6$((' -"37*"3)' 69)%' 39)' 273073' #2(3"&)' *)".9)",273'+CT'`'$%'39)'02-$3$#)'+$*).3$2%'"%+'nCT'`'$%'39)'%)&"3$#)'+$*).3$2%>'S2*'39$-'0"*3$.7("* 20'"/0'39)'%,&$1*.)&()&*#.-&,'$'$-'-"$+'32',)'±CT'`>';2'"#2$+'.($00$%&'211'39)'0)"8-'21'39) 273073'6"#)12*/5'"%+'39)'*)-7(3$%&'6"#)12*/'+$-32*3$2%5'39)'$%073'-$&%"('/7-3',)'8)03'.2**)B -02%+$%&(4'-/"((>
2.8.2 Output Current Limits H%239)*' ($/$3"3$2%'2%'39)' 20)*"3$2%'21'20'"/0-'$-'39"3' 39)$*'273073'.7**)%3'$-'($/$3)+'32'" -0).$1$)+'/"M$/7/>'S2*'$%-3"%.)5'39)'0207("*'IUC'20'"/0'$-'-0).$1$)+'32'9"#)'"'/"M$/7/ 273073' .7**)%3' 21' ±QF' /H>' ;97-5' $%' +)-$&%$%&' .(2-)+B(220' .$*.7$3-' 73$($[$%&' 39)' IUC5' 39) +)-$&%)*'9"-'32')%-7*)'39"3'7%+)*'%2'.2%+$3$2%'6$(('39)'20'"/0',)'*)K7$*)+'32'-700(4'"%'273B 073'.7**)%35'$%')$39)*'+$*).3$2%5')M.))+$%&'QF'/H>';9$-5'21'.27*-)5'9"-'32'$%.(7+)',239'39) .7**)%3'$%'39)'1))+,".8'.$*.7$3'"-'6)(('"-'39)'.7**)%3'-700($)+'32'"'(2"+'*)-$-32*>'A1'39)'.$*.7$3 *)K7$*)-'"'("*&)*'.7**)%35'39)'20B"/0'273073'#2(3"&)'6$(('-"37*"3)'"3'39)'()#)('.2**)-02%+$%& 32'39)'/"M$/7/'"((26)+'273073'.7**)%3>
103
2.8 Large-Signal Operation of Op Amps
Example 2.7 G2%-$+)*'39)'%2%$%#)*3$%&'"/0($1$)*'.$*.7$3'-926%'$%'S$&>'Q>UQ>'H-'-926%5'39)'.$*.7$3'$-'+)-$&%)+'12* "'%2/$%"('&"$%' ( C + ? Q ⁄ ? C ) = CF'`d`>'A3'$-'1)+'6$39'"'(26B1*)K7)%.4'-$%)B6"#)'-$&%"('21'0)"8'#2(3"&) !+'"%+'$-'.2%%).3)+'32'"'(2"+'*)-$-32*'?D>';9)'20'"/0'$-'-0).$1$)+'32'9"#)'273073'-"37*"3$2%'#2(3"&)21'±CT'`'"%+'273073'.7**)%3'($/$3-'21'±QF'/H> <"= S2*'!+'='C'`'"%+'?D'='C'8Ω, -0).$14'39)'-$&%"('*)-7(3$%&'"3'39)'273073'21'39)'"/0($1$)*> <,= S2*'!+'='C>V'`'"%+'?D'='C'8Ω5'-0).$14'39)'-$&%"('*)-7(3$%&'"3'39)'273073'21'39)'"/0($1$)*> <.= S2*'?D' ='C'8Ω5'69"3'$-'39)'/"M$/7/'#"(7)'21'!+'12*'69$.9'"%'7%+$-32*3)+'-$%)B6"#)'273073'$2,3"$%)+\ <+= S2*' !+' =' C' `5' 69"3' $-' 39)' (26)-3' #"(7)' 21' ?D' 12*' 69$.9' "%' 7%+$-32*3)+' -$%)B6"#)' 273073' $2,3"$%)+\ vO
15 V
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Figure 2.42 :,;'H'%2%$%#)*3$%&'"/0($1$)*'6$39'"'%2/$%"('&"$%'21'CF `d`'+)-$&%)+'7-$%&'"%'20'"/0'39"3'-"37*"3)-'"3 ±CTB`'273073'#2(3"&)'"%+'9"-'±QFB/H'273073'.7**)%3'($/$3->':5;*Y9)%'39)'$%073'-$%)'6"#)'9"-'"'0)"8'21'C>V `5'39) 273073'$-'.($00)+'211'"3'±CT'`>
Solution <"= S2*'!+'='C'`'"%+'?D'='C'8Ω5'39)'273073'6$((',)'"'-$%)'6"#)'6$39'0)"8'#"(7)'21'CF'`>';9$-'$(26)*'39"%'273073'-"37*"3$2%'()#)(-'21'±CT'`5'"%+'397-'39)'"/0($1$)*'$-'%23'($/$3)+'39"3'6"4>'H(-25 69)%'39)'273073'$-'"3'$3-'0)"8'<,= P26'$1'!+'$-'$%.*)"-)+'32'C>V'`5'$+)"((4'39)'273073'627(+',)'"'-$%)'6"#)'21'CVB`'0)"8>';9)'20 "/05'926)#)*5'6$(('-"37*"3)'"3'±CT'`5'397-'.($00$%&'39)'-$%)B6"#)'273073'"3'39)-)'()#)(->'k)3J%)M3'.9).8'2%'39)'20B"/0'273073'.7**)%3:'H3'CTB`'273073'"%+'?D'='C'8Ω5')D'='CT'/H'"%+')J'= C>T'/HX'397-')B'='CU>T'/H5'"&"$%'7%+)*'39)'QFB/H'($/$3>';97-'39)'273073'6$((',)'"'-$%)'6"#) 6$39'$3-'0)"8-'.($00)+'211'"3'±CT'`5'"-'-926%'$%'S$&>'Q>UQ<,=>
104 Chapter 2 Operational Amplifiers
Example 2.7 continued
<.= S2*'?D'='C'8Ω5'39)'/"M$/7/'#"(7)'21'!+'12*'7%+$-32*3)+'-$%)B6"#)'273073'$-'C>T'`>';9)'273073 6$((',)'"'CTB`'0)"8'-$%)'6"#)5'"%+'39)'20B"/0'273073'.7**)%3'"3'39)'0)"8-'6$((',)'CU>T'/H> <+= S2*'!+'='C'`'"%+'?D'*)+7.)+5'39)'(26)-3'#"(7)'02--$,()'12*'?D'69$()'39)'273073'$-'*)/"$%$%&'"% 7%+$-32*3)+'-$%)'6"#)'21'CFB`'0)"8'."%',)'127%+'1*2/ CF'` CF'` ) B/"M = QF'/H = BBBBBBBBBBBB + BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB ? D/$% D'8Ω + C'8Ω
69$.9'*)-7(3-'$% ? D/$% = VQE'Ω
2.8.3 Slew Rate H%239)*' 09)%2/)%2%' 39"3' ."%' ."7-)' %2%($%)"*' +$-32*3$2%' 69)%' ("*&)' 273073' -$&%"(-' "*) 0*)-)%3'$-'-()6B*"3)'($/$3$%&>';9)'%"/)'*)1)*-'32'39)'1".3'39"3'39)*)'$-'"'-0).$1$.'-/C)-,8/&(%12%0'/*<('02--$,()'"3'39)'273073'21'"'*)"('20'"/0>';9$-'/"M$/7/'$-'8%26%'"-'39)'4-$8 %,&$'
.v B LO = BBBBBBBB B .&
VE= /"M
"%+'$-'7-7"((4'-0).$1$)+'2%'39)'20B"/0'+"3"'-9))3'$%'7%$3-'21'`dµ->' A3'12((26-'39"3'$1'39)'$%073 -$&%"('"00($)+'32'"%'20B"/0'.$*.7$3'$-'-7.9'39"3'$3'+)/"%+-'"%'273073'*)-02%-)'39"3'$-'1"-3)* 39"%'39)'-0).$1$)+'#"(7)'21'LO5'39)'20'"/0'6$(('%23'.2/0(4>'O"39)*5'$3-'273073'6$(('.9"%&)'"3 39)'/"M$/7/'02--$,()'*"3)5'69$.9'$-')K7"('32'$3-'LO>'H-'"%')M"/0()5'.2%-$+)*'"%'20'"/0 .2%%).3)+'$%'39)'7%$34B&"$%'#2(3"&)B12((26)*'.2%1$&7*"3$2%'-926%'$%'S$&>'Q>UT<"=5'"%+'()3'39) $%073'-$&%"(',)'39)'-3)0'#2(3"&)'-926%'$%'S$&>'Q>UT<,=>';9)'273073'21'39)'20'"/0'6$(('%23',) ",()'32'*$-)'$%-3"%3"%)27-(4'32'39)'$+)"('#"(7)'!X'*"39)*5'39)'273073'6$((',)'39)'($%)"*'*"/0'21 -(20)')K7"('32'LO5'-926%'$%'S$&>'Q>UT<.=>';9)'"/0($1$)*'$-'39)%'-"$+'32',)'4-$8!"'5'"%+'$3273073'$-'4-$8/%,&$*-!+!&$1> A%'2*+)*'32'7%+)*-3"%+'39)'2*$&$%'21'39)'-()6B*"3)'09)%2/)%2%5'6)'%))+'32'8%26'",273 39)'$%3)*%"('.$*.7$3'21'39)'20'"/05'"%+'6)'6$(('-37+4'$3'$%'G9"03)*'CQ>'S2*'39)'3$/)',)$%&5 926)#)*5'$3'$-'-711$.$)%3'32'8%26'",273'39)'09)%2/)%2%'"%+'32'%23)'39"3'$3'$-'+$-3$%.3'1*2/ 39)'1$%$3)'20B"/0',"%+6$+39'39"3'($/$3-'39)'1*)K7)%.4'*)-02%-)'21'39)'.(2-)+B(220'"/0($1$B )*-5' -37+$)+' $%' 39)' 0*)#$27-' -).3$2%>' ;9)' ($/$3)+' ,"%+6$+39' $-' "' ($%)"*' 09)%2/)%2%' "%+ +2)-'%23'*)-7(3'$%'"'.9"%&)'$%'39)'-9"0)'21'"%'$%073'-$%7-2$+X'39"3'$-5'$3'+2)-'%23'()"+'32'%2%B ($%)"*'+$-32*3$2%>';9)'-()6B*"3)'($/$3"3$2%5'2%'39)'239)*'9"%+5'."%'."7-)'%2%($%)"*'+$-32*3$2% 32' "%' $%073' -$%7-2$+"(' -$&%"(' 69)%' $3-' 1*)K7)%.4' "%+' "/0($37+)' "*)' -7.9' 39"3' 39)' .2**)B -02%+$%&'$+)"('273073'627(+'*)K7$*)'vB'32'.9"%&)'"3'"'*"3)'&*)"3)*'39"%'LO>';9$-'$-'39)'2*$B &$%'21'"%239)*'*)("3)+'20B"/0'-0).$1$."3$2%5'$3-'17((B026)*',"%+6$+395'32',)')M0("$%)+'("3)*> e)12*)'()"#$%&'39)')M"/0()'$%'S$&>'Q>UT5'926)#)*5'6)'-927(+'02$%3'273'39"3'$1'39)'-3)0 $%073'#2(3"&)'!'$-'-711$.$)%3(4'-/"((5'39)'273073'."%',)'39)')M02%)%3$"((4'*$-$%&'*"/0'-926%'$% S$&>'Q>UT<+=>'L7.9'"%'273073'627(+',)')M0).3)+'1*2/'39)'12((26)*'$1'39)'2%(4'($/$3"3$2%'2%'$3+4%"/$.'0)*12*/"%.)'6)*)'39)'1$%$3)'20B"/0',"%+6$+39>'L0).$1$."((45'39)'3*"%-1)*'17%.3$2%'21 39)'12((26)*'."%',)'127%+',4'-7,-3$373$%&'?C'='∞'"%+'?Q'='F'$%'@K>'VV='32'2,3"
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2.8 Large-Signal Operation of Op Amps
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EXERCISE 2.29 H%'20'"/0'39"3'9"-'"'-()6'*"3)'21'C'`dµ-'"%+'"'7%$34B&"$%',"%+6$+39'2&'21'C'R!['$-'.2%%).3)+'$%'39) 7%$34B&"$%'12((26)*'.2%1$&7*"3$2%>'S$%+'39)'("*&)-3'02--$,()'$%073'#2(3"&)'-3)0'12*'69$.9'39)'273073 6"#)12*/'6$(('-3$((',)'&$#)%',4'39)')M02%)%3$"('*"/0'21'@K>'Vc=>'S2*'39$-'$%073'#2(3"&)5'69"3'$39)'CFg'32'DFg'*$-)'3$/)'21'39)'273073'6"#)12*/\'A1'"%'$%073'-3)0'CF'3$/)-'"-'("*&)'$-'"00($)+5'1$%+ 39)'CFg'32'DFg'*$-)'3$/)'21'39)'273073'6"#)12*/> Ans. F>CE'`X'F>TV'µ-X'C>Qc'µ-
105
106 Chapter 2 Operational Amplifiers
2.8.4 Full-Power Bandwidth ?0B"/0'-()6B*"3)'($/$3$%&'."%'."7-)'%2%($%)"*'+$-32*3$2%'$%'-$%7-2$+"('6"#)12*/->'G2%-$+)* 2%.)'/2*)'39)'7%$34B&"$%'12((26)*'6$39'"'-$%)B6"#)'$%073'&$#)%',4
v > = !u) -$% ω & ;9)'*"3)'21'.9"%&)'21'39$-'6"#)12*/'$-'&$#)%',4
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ω N !1/"M = LO ;97-5
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2.8 Large-Signal Operation of Op Amps
107
EXERCISE 2.30' H%'20'"/0'9"-'"'*"3)+'273073'#2(3"&)'21'±CF'`'"%+'"'-()6'*"3)'21'C'`dµ->'Y9"3'$-'$3-'17((B026)* ,"%+6$+39\'A1'"%'$%073'-$%7-2$+'6$39'1*)K7)%.4'2'='V2N'$-'"00($)+'32'"'7%$34B&"$%'12((26)*'.2%B -3*7.3)+'7-$%&'39$-'20'"/05'69"3'$-'39)'/"M$/7/'02--$,()'"/0($37+)'39"3'."%',)'"..2//2+"3)+ "3'39)'273073'6$39273'$%.7**$%&'LO'+$-32*3$2%\ Ans. CV>D'8![X'Q'`'<0)"8=
Summary ;9)'AG'20'"/0'$-'"'#)*-"3$()'.$*.7$3',7$(+$%&',(2.8>'A3'$)"-4' 32' "00(45' "%+' 39)' 0)*12*/"%.)' 21' 20B"/0' .$*.7$3.(2-)(4'/"3.9)-'39)2*)3$."('0*)+$.3$2%-> ;9)'20B"/0'3)*/$%"(-'"*)'39)'$%#)*3$%&'$%073'3)*/$%"(';9)'.2//2%'3)*/$%"('21'39) 362'-700($)-'$-'39)'.$*.7$3'&*27%+> ;9)'$+)"('20'"/0'*)-02%+-'2%(4'32'39)'+$11)*)%.)'$%073 -$&%"(5' 39"3' $-5 ( v Q ! v C )X ' 0*2#$+$%&' "3' 39)' 2730735' ,)B 36))%'3)*/$%"('T'"%+'&*27%+5'"'-$&%"(' $ ( v Q ! v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⁄ !) = ! ? Q ⁄ ? C X '"%+'12*'39)'%2%$%#)*3$%&'.2%1$&7*"3$2%5 !1 ⁄ !) = C + ? Q ⁄ ? C >
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108 Chapter 2 Operational Amplifiers G2%%).3$%&'"'("*&)'*)-$-3"%.)'$%'0"*"(()('6$39'39)'."0".$B 32*' 21' /%' 20B"/0' $%#)*3$%&' $%3)&*"32*' 0*)#)%3-' 20B"/0 -"37*"3$2%'<+7)'32'39)')11).3''21'!BK'"%+'>L=> S2*'/2-3'$%3)*%"((4'.2/0)%-"3)+'20'"/0-5'39)'20)%B(220 &"$%'1"((-'211'6$39'1*)K7)%.4'"3'"'*"3)'21'−QF'+ed+)."+)5 *)".9$%&' 7%$34' "3' "' 1*)K7)%.4' 2&' <39)' 7%$34B&"$%' ,"%+B 6$+39=>'S*)K7)%.4'2&''$-'"(-2'8%26%'"-'39)'&"$%n,"%+6$+39 0*2+7.3'21'39)'20'"/0:'2&'='$F'255'69)*)'$F'$-'39)'+.'&"$%5 "%+'25'$-'39)'TB+e'1*)K7)%.4'21'39)'20)%B(220'&"$%>'H3'"%4 1*)K7)%.4'2 < 2 )'25=5'39)'20B"/0'&"$%' $ ! 2& ⁄ 2>
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Problems 109
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Figure P2.8
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CHAPTER 2
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CHAPTER 2
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CHAPTER 2
PROBLEMS
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PROBLEMS
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CHAPTER 2
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CHAPTER 3
Semiconductors
Introduction 3.1
3.5 The pn!Junction with Applied Voltage 145
125
Intrinsic Semiconductors
3.2 Doped Semiconductors
126
3.6 Capacitive Effects in the pn Junction 154
129
3.3 Current Flow in Semiconductors
132
3.4 The pn!Junction with Open-Circuit Terminals (Equilibrium) 138
Summary
157
Problems
159
IN THIS CHAPTER YOU WILL LEARN 1. The basic properties of semiconductors and in particular silicon, which is the material used to make most of today’s electronic circuits. 2. How doping a pure silicon crystal dramatically changes its electrical conductivity, which is the fundamental idea underlying the use of semiconductors in the implementation of electronic devices. 3. The two mechanisms by which current flows in semiconductors: drift and diffusion of charge carriers. 4. The structure and operation of the "#!junction; a basic semiconductor structure that implements the diode and plays a dominant role in transistors.
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125
126 Chapter 3 Semiconductors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3.1 Intrinsic Semiconductors
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127
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3.2 Doped Semiconductors 129
EXERCISE 3.1 <'-0#-'.*%."*%/2.(/2$/0%0'((/*(%,*2$/.5% # + %&1(%$/-/012%'.%)%e%DU%Y%'2,%KDU%Y: " KT K K Ans. T:E × SU ⁄ 06 L% B:SD × SU SS ⁄ 06
3.2 Doped Semiconductors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ovalent bonds
Valence electrons !
!
!
! "4 ! !
! "4 ! !
! "4 ! !
!
!
!
! "4 ! !
! "5 ! !
! "4 ! !
!
!
!
! "4 ! !
! "4 ! !
! "4 ! !
!
Free electron donated by impurity atom Pentavalent impurity atom (donor)
Silicon atoms
Figure 3.3 G%$/-/012%0(5$.'-%,17*,%45%'%7*2.'+'-*2.%*-*6*2.:%O'0"%,17'2.%'.16%,12'.*$%'%&(**%*-*0.(12 '2,%/$%."#$%0'--*,%'%,121(:%!"*%,17*,%$*6/012,#0.1(%4*016*$%#%.57*:
130 Chapter 3 Semiconductors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
AK:BC
)"*(*%."*%$#4$0(/7.%#!,*21.*$%#?.57*%$/-/012:%!"#$% # # %/$%,*.*(6/2*,%45%."*%,17/28%0120*2? .('./12%'2,%21.%45%.*67*('.#(*:%!"/$%/$%21.%."*%0'$*3%"1)*+*(3%&1(%."*%"1-*%0120*2.('./12:%G-."*%"1-*$%/2%."*%#?.57*%$/-/012%'(*%."1$*%8*2*('.*,%45%."*(6'-%/12/X'./12:%!"*/(%0120*2.('./12 " # %0'2%4*%&1#2,%45%21./28%."'.%."*%(*-'./12$"/7%/2%OV:%AK:KC%'77-/*$%*V#'--5%)*--%&1(%,17*, $/-/0123%7(1+/,*,%."*(6'-%*V#/-/4(/#6%/$%'0"/*+*,:%!"#$%&1(%#?.57*%$/-/012 =
"# ## % ! #+
J#4$./.#./28%&1(% # # %&(16%OV:%AK:BC3%)*%14.'/2%&1(% " # =
# " # ! ??????+? 12
AK:DC =
!"#$% " # %)/--%"'+*%."*%$'6*%,*7*2,*20*%12%.*67*('.#(*%'$%."'.%1&% # + :%;/2'--53%)*%21.* ."'.%/2%#?.57*%$/-/012%."*%0120*2.('./12%1&%&(**%*-*0.(12$% # # %)/--%4*%6#0"%-'(8*(%."'2%."'.%1& "1-*$:% f*20*% *-*0.(12$% '(*% $'/,% .1% 4*% ."*% ,'6-&!#4% 0"'(8*% 0'((/*($% '2,% "1-*$% ."*% ,!"-&!#4 0"'(8*%0'((/*($%/2%#?.57*%$/-/012: !1%14.'/2%"?.57*%$/-/012%/2%)"/0"%"1-*$%'(*%."*%6'F1(/.5%0"'(8*%0'((/*($3%'%.(/+'-*2.%/67#? (/.5%$#0"%'$%41(12%/$%#$*,:%;/8#(*%K:B%$"1)$%'%$/-/012%0(5$.'-%,17*,%)/."%41(12:%a1.*%."'.%."* 41(12% '.16$% (*7-'0*% $16*% 1&% ."*% $/-/012% '.16$% /2% ."*% $/-/012% 0(5$.'-% $.(#0.#(*:% J/20*% *'0" Covalent bonds
Valence electrons
Silicon atom !
!
!
! "4 ! !
! "4 ! !
! "4 ! !
!
!
!
! "4 ! !
! "3 ! !
! "4 ! !
!
!
"
! "4 ! !
! "4 ! !
! "4 ! !
Trivalent impurity atom (acceptor)
Electron accepted from this atom, thus creating a hole
Figure 3.4 G%$/-/012%0(5$.'-%,17*,%)/."%'%.(/+'-*2.%/67#(/.5:%O'0"%,17'2.%'.16%8/+*$%(/$*%.1%'%"1-*3%'2, ."*%$*6/012,#0.1(%4*016*$%"%.57*:
3.2 Doped Semiconductors
41(12%'.16%"'$%."(**%*-*0.(12$%/2%/.$%1#.*(%$"*--3%/.%'**$0#5%'2%*-*0.(12%&(16%'%2*/8"41(/28 '.163%."#$%&1(6/28%01+'-*2.%412,$:%!"*%(*$#-.%/$%'%"1-*%/2%."*%2*/8"41(/28%'.16%'2,%'%41#2, 2*8'./+*%0"'(8*%'.%."*%'**$0#-&%A41(12C%'.16:%>.%&1--1)$%."'.%*'0"%'00*7.1(%'.16%7(1+/,*$%' "1-*:% >&% ."*% '00*7.1(% ,17/28% 0120*2.('./12% /$% 1 3 3% )"*(*% 1 3 # # + L % ."*% "1-*% 0120*2.('./12 4*016*$ AK:EC
" " %! 1 3
)"*(*%."*%$#4$0(/7.%"!,*21.*$%"?.57*%$/-/012:%!"#$3%"*(*%."*%6'F1(/.5%0'((/*($%'(*%"1-*$%'2, ."*/(% 0120*2.('./12% /$% ,*.*(6/2*,% 45% 13:% !"*% 0120*2.('./12% 1&% 6/21(/.5% *-*0.(12$% 0'2% 4* &1#2,%45%#$/28%."*%(*-'./12$"/7% =
"" #" % ! #+
'2,%$#4$./.#./28%&1(% " " %&(16%OV:%AK:EC3 =
# # " ! ?????+? 13
AK:bC
!"#$3% ."*% 0120*2.('./12% 1&% ."*% 6/21(/.5% *-*0.(12$% )/--% "'+*% ."*% $'6*% .*67*('.#(*% ,*7*2? = ,*20*%'$%."'.%1&% # + : >.%$"1#-,%4*%*67"'$/X*,%."'.%'%7/*0*%1&%#?.57*%1(%"?.57*%$/-/012%/$%*-*0.(/0'--5%2*#.('-L%."* 0"'(8*%1&%."*%6'F1(/.5%&(**%0'((/*($%A*-*0.(12$%/2%."*%#?.57*%'2,%"1-*$%/2%."*%"?.57*%$/-/012C%'(* 2*#.('-/X*,%45%."*%41#2,%0"'(8*$%'$$10/'.*,%)/."%."*%/67#(/.5%'.16$:
Example 3.2 Sb
K
<12$/,*(% '2%#?.57*% $/-/012% &1(% )"/0"% ."*% ,17'2.% 0120*2.('./12% 1 2 ! SU ⁄ 06 :% ;/2,% ."*% *-*0.(12% '2, "1-*%0120*2.('./12$%'.%)%%e%KUU%Y:
Solution !"*%0120*2.('./12%1&%."*%6'F1(/.5%*-*0.(12$%/$ Sb
# # ! 1 2 ! SU ⁄ 06
K
!"*%0120*2.('./12%1&%."*%6/21(/.5%"1-*$%/$ =
# " # ! ??????+? 12 SU
K
>2%O@'67-*%K:S%)*%&1#2,%."'.%'.%)%e%KUU%Y3% # + ! S:D × SU ⁄ 06 :%!"#$3 SU =
S:D × SU ) " # ! (?????????????????????????????? ? Sb SU K
! =:=D × SU ⁄ 06 R4$*(+*%."'.% # # # # + %'2,%."'.% # # %/$%+'$.-5%"/8"*(%."'2% " #:
K
131
132 Chapter 3 Semiconductors
EXERCISES 3.2 ;1(%."*%$/.#'./12%/2%O@'67-*%K:=3%&/2,%."*%*-*0.(12%'2,%"1-*%0120*2.('./12$%'.%KDU%Y:%g1#%6'5%#$* ."*%+'-#*%1&% # + %'.%)!e%KDU%Y%&1#2,%/2%O@*(0/$*%K:S: Sb K E K Ans. # # ! SU ⁄ 063 % " # ! S:b= × SU ⁄ 06 3.3 ;1(%'%$/-/012%0(5$.'-%,17*,%)/."%41(123%)"'.%6#$.% 1 3 %4*%/&%'.%)%e%KUU%Y%."*%*-*0.(12%0120*2.('./12 E ,(17$%4*-1)%."*%/2.(/2$/0%-*+*-%45%'%&'0.1(%1&% SU h SE K Ans. 1 3 ! S:D × SU ⁄ 06
3.3 Current Flow in Semiconductors !"*(*% '(*% .)1% ,/$./20.-5% ,/&&*(*2.% 6*0"'2/$6$% &1(% ."*% 61+*6*2.% 1&% 0"'(8*% 0'((/*($% '2, "*20*%&1(%0#((*2.%&-1)%/2%$*6/012,#0.1($H%,(/&.%'2,%,/&$/12:
3.3.1 Drift Current \"*2%'2%*-*0.(/0'-%&/*-,%&%/$%*$.'4-/$"*,%/2%'%$*6/012,#0.1(%0(5$.'-3%"1-*$%'(*%'00*-*('.*,%/2 ."*%,/(*0./12%1&%&3%'2,%&(**%*-*0.(12$%'(*%'00*-*('.*,%/2%."*%,/(*0./12%1771$/.*%.1%."'.%1&%&: !"/$%$/.#'./12%/$%/--#$.('.*,%/2%;/8:%K:D:%!"*%"1-*$%'0V#/(*%'%+*-10/.5%4"?,(/&.%8/+*2%45 4"?,(/&.%e%µ"&
AK:cC
)"*(*% µ"%/$%'%012$.'2.%0'--*,%."*%/-.$),-2!.!#4H%>.%(*7(*$*2.$%."*%,*8(**%1&%*'$*%45%)"/0" "1-*$%61+*%."(1#8"%."*%$/-/012%0(5$.'-%/2%(*$712$*%.1%."*%*-*0.(/0'-%&/*-,%&:%J/20*%+*-10/.5%"'$ ."*%#2/.$%1&%0*2./6*.*($%7*(%$*012,%'2,!&%"'$%."*%#2/.$%1&%+1-.$%7*(%0*2./6*.*(3%)*%$**%&(16 OV:% AK:cC% ."'.% ."*% 614/-/.5% µ"% 6#$.% "'+*% ."*% #2/.$% 1&% 0*2./6*.*($% $V#'(*,% 7*(% +1-.?$*012, A06=`P:$C:%;1(%/2.(/2$/0%$/-/012% µ " ! BcU %06=`P : $: !"*%&(**%*-*0.(12$%'0V#/(*%'%,(/&.%+*-10/.5% 4 #?,(/&. %8/+*2%45 4#?,(/&. %e %]µ# &
AK:TC
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Figure 3.5 G2% *-*0.(/0% &/*-,% &% *$.'4-/$"*,% /2% ' 4'(%1&%$/-/012%0'#$*$%."*%"1-*$%.1%,(/&.%/2%."*%,/(*0? ./12%1&%&%'2,%."*%&(**%*-*0.(12$%.1%,(/&.%/2%."*%1771? $/.*% ,/(*0./12:% M1."% ."*% "1-*% '2,% *-*0.(12% ,(/&. 0#((*2.$%'(*%/2%."*%,/(*0./12%1&%&:
3.3 Current Flow in Semiconductors
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AK:SUC
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\*% '(*% #$#'--5% /2.*(*$.*,% /2% ."*% 0#((*2.% ,*2$/.5% 9" 3% )"/0"% /$% ."*% 0#((*2.% 7*(% #2/.% 0(1$$? $*0./12'-%'(*'3 6" 9 " ! ???? ! $" µ " & AK:SSC 3 !"*% 0#((*2.% 016712*2.% ,#*% .1% ."*% ,(/&.% 1&%&(**%*-*0.(12$% 0'2% 4*%&1#2,% /2% '% $/6/-'(% 6'22*(: a1.*3%"1)*+*(3%."'.%*-*0.(12$%,(/&./28%&(16%(/8".%.1%-*&.%(*$#-.%/2%'%0#((*2.%016712*2.%&(16%-*&. .1%(/8".:%!"/$%/$%4*0'#$*%1&%."*%012+*2./12%1&%.'9/28%."*%,/(*0./12%1&%0#((*2.%&-1)%'$%."*%,/(*0? ./12%1&%&-1)%1&%71$/./+*%0"'(8*%'2,%1771$/.*%.1%."*%,/(*0./12%1&%&-1)%1&%2*8'./+*%0"'(8*:%!"#$3 6#% e% ]3$#4#?,(/&. J#4$./.#./28%&1(%v#?,(/&.%&(16%OV:%AK:TC3%)*%14.'/2%."*%0#((*2.%,*2$/.5% 9 # ! 6 # ⁄ 3 %'$% 9 # ! $# µ # &
AK:S=C
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AK:SKC
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AK:SBC
9 ! &⁄ρ
AK:SDC
σ ! $ ( " µ" # # µ# )
AK:SEC
S S ? ρ ≡ ??? ! ??????????????????????????????? σ $ ( " µ" # # µ# )
AK:SbC
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P ⁄ 06 : !"#$%."*%#2/.$%1&%ρ%'(*%1"6:0*2./6*.*($% Ω ⋅ 06 ! ????????????????? = G ⁄ 06
AK:ScC
133
134 Chapter 3 Semiconductors
Example 3.3 SE
K
;/2,% ."*% (*$/$./+/.5% 1&% A'C% /2.(/2$/0% $/-/012% '2,% A4C% "?.57*% $/-/012% )/."% 1 3 % ! SU ⁄ 06 :% i$* SU = # + % ! S:D × SU ⁄ 06 K3% '2,% '$$#6*% ."'.% &1(% /2.(/2$/0% $/-/012% µ # % ! SKDU 06 ⁄ P : $% '2, = = = µ " % ! BcU 06 ⁄ P : $3% '2,% &1(% ."*% ,17*,% $/-/012% µ # % ! SSSU 06 ⁄ P : $% '2,% µ " % ! BUU 06 ⁄ P : $: Aa1.*%."'.%,17/28%(*$#-.$%/2%(*,#0*,%0'((/*(%614/-/./*$C: Solution A'C%;1(%/2.(/2$/0%$/-/0123 SU
" ! # ! # + ! S:D × SU ⁄ 06
K
!"#$3 S ρ ! ??????????????????????????????? ? $ ( " µ" # # µ# ) S ρ ! ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? " ST SU SU S:E × SU ( S:D × SU × BcU # S:D × SU × SKDU ) D
! =:=c × SU Ω :%%06 A4C%;1(%."*%"?.57*%$/-/012 SE
" " ! 1 3 ! SU ⁄ 06
K
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!"#$3 S ρ ! ??????????????????????????????? ? $ ( " µ" # # µ# ) S ! ?????????????????????????????????????????????????????????????????????????????????????????????????????????? ? " ST SE B S:E × SU ( SU × BUU # =:=D × SU × SSSU ) S ? ! S:DE Ω :%%06 ! ????????????????????????????????????????????????????????? " ST SE S:E × SU × SU × BUU
R4$*(+*%."'.%."*%(*$/$./+/.5%1&%."*%"?.57*%$/-/012%/$%,*.*(6/2*,%'-61$.%*2./(*-5%45%."*%,17/28%0120*2? D .('./12:%G-$1%14$*(+*%."'.%,17/28%."*%$/-/012%(*,#0*$%/.$%(*$/$./+/.5%45%'%&'0.1(%1&%'41#.% SU 3%'%.(#-5 (*6'(9'4-*%0"'28*:
3.3 Current Flow in Semiconductors 135
EXERCISE 3.4 G% #2/&1(6% 4'(% 1&% #?.57*% $/-/012% 1&% =% µ6% -*28."% "'$% '% +1-.'8*% 1&% S% P% '77-/*,% '0(1$$% /.:% >& SE K = 1 2 ! SU ⁄ 06 %'2,% µ # ! SKDU 06 ⁄ P :$3%&/2,%A'C%."*%*-*0.(12%,(/&.%+*-10/.53%A4C%."*%./6*%/.%.'9*$%'2 *-*0.(12%.1%0(1$$%."*%=?µ6%-*28."3%A0C%."*%,(/&.?0#((*2.%,*2$/.53%'2,%A,C%."*%,(/&.%0#((*2.%/2%."*%0'$* = ."*%$/-/012%4'(%"'$%'%0(1$$%$*0./12'-%'(*'%1&% U:=D µ6 : E B = Ans. E:bD × SU %06`$L%KU%7$L%S:Uc × SU G ⁄ 06 L%=b%µG
3.3.2 Diffusion Current <'((/*(%,/&$/12%100#($%)"*2%."*%,*2$/.5%1&%0"'(8*%0'((/*($%/2%'%7/*0*%1&%$*6/012,#0.1(%/$ 21.%#2/&1(6:%;1(%/2$.'20*3%/&%45%$16*%6*0"'2/$6%."*%0120*2.('./12%1&3%$'53%"1-*$3%/$%6',* "/8"*(% /2% 12*% 7'(.% 1&% '% 7/*0*% 1&% $/-/012% ."'2% /2% '21."*(3% ."*2% "1-*$% )/--% ,/&$*% &(16% ."* (*8/12%1&%"/8"%0120*2.('./12%.1%."*%(*8/12%1&%-1)%0120*2.('./12:%J#0"%'%,/&$/12%7(10*$$%/$ -/9*%."'.%14$*(+*,%/&%12*%,(17$%'%&*)%/29%,(17$%/2%'%)'.*(?&/--*,%.'29:%!"*%,/&$/12%1&%0"'(8* 0'((/*($%8/+*$%(/$*%.1%'%2*.%&-1)%1&%0"'(8*3%1(%(!33+5!-")*+&&$"#: G$%'2%*@'67-*3%012$/,*(%."*%4'(%1&%$/-/012%$"1)2%/2%;/8:%K:EA'CH%M5%$16*%#2$7*0/&/*, 7(10*$$3% )*% "'+*% '(('28*,% .1% /2F*0.% "1-*$% /2.1% /.$% -*&.% $/,*:% !"/$% 012./2#1#$% "1-*% /2F*0./12 8/+*$%(/$*%.1%'2,%6'/2.'/2$%'%"1-*%*-"*$"#&'#!-")0&-3!.$%$#0"%'$%."'.%$"1)2%/2%;/8:%K:EA4C: !"/$%7(1&/-*%/2%.#(2%0'#$*$%"1-*$%.1%,/&$*%&(16%-*&.%.1%(/8".%'-128%."*%$/-/012%4'(3%(*$#-./28%/2 '%"1-*%0#((*2.%/2%."*%5%,/(*0./12:%!"*%6'82/.#,*%1&%."*%0#((*2.%'.%'25%71/2.%/$%7(171(./12'-%.1 ."*%$-17*%1&%."*%0120*2.('./12%7(1&/-*3%1(%."*%*-"*$"#&'#!-")%&'(!$"#3%'.%."'.%71/2.3% ," ( 5 ) 9 " ! " $2 " ?????????????? ,5 "
Hole injection
AK:STC
" "" " " " " " " " "" " " " " " " " " " " " " " " " " " " " "
(a)
x
Hole concentration, p
Hole diffusion Hole current
x
0 (b)
Figure 3.6 G% 4'(% 1&% $/-/012) 7'8% /2.1 )"/0"% "1-*$% '(*% /2F*0.*,3% ."#$% 0(*'./28% ."* "1-*%0120*2.('./12%7(1&/-*%'-128%."*%5%'@/$3 $"1)2%/2%728:%!"*%"1-*$%,/&$*%/2%."*%71$/? ./+*% ,/(*0./12% 1&% 5% '2,% 8/+*% (/$*% .1% '% "1-*? ,/&$/12% 0#((*2.% /2% ."*% $'6*% ,/(*0./12: a1.*%."'.%)*%'(*%21.%$"1)/28%."*%0/(0#/.%.1 )"/0"%."*%$/-/012%4'(%/$%0122*0.*,:
136 Chapter 3 Semiconductors =
)"*(*% 9 "%/$%."*%"1-*?0#((*2.%,*2$/.5%A G ⁄ 06 C3%$%/$%."*%6'82/.#,*%1&%*-*0.(12%0"'(8*3% 2 "%/$%' 012$.'2.% 0'--*,% ."*% (!33+5!-") *-"5#'"#% 1(% (!33+5!1!#4% 1&% "1-*$L% '2,% " ( 5 )% /$% ."*% "1-* 0120*2.('./12%'.%71/2.%5:%a1.*%."'.%."*%8(',/*2.% ( ," ⁄ ,5 ) %/$%2*8'./+*3%(*$#-./28%/2%'%71$/./+* 0#((*2.%/2%."*%5%,/(*0./123%'$%$"1#-,%4*%*@7*0.*,: >2%."*%0'$*%1&%*-*0.(12%,/&$/12%(*$#-./28%&(16%'2%*-*0.(12%0120*2.('./12%8(',/*2.%A$** ;/8:%K:bC3%'%$/6/-'(%(*-'./12$"/7%'77-/*$3%8/+/28%."*%*-*0.(12?0#((*2.%,*2$/.53 ,# ( 5 ) 9 # ! $2 # ?????????????? ,5
AK:=UC
)"*(*% 2 # %/$%."*%,/&$/12%012$.'2.%1(%,/&$/+/.5%1&%*-*0.(12$:%R4$*(+*%."'.%'%2*8'./+*%A,#`,5C 8/+*$%(/$*%.1%'%2*8'./+*%0#((*2.3%'%(*$#-.%1&%."*%012+*2./12%."'.%."*%71$/./+*%,/(*0./12%1&%0#((*2. /$%.'9*2%.1%4*%."'.%1&%."*%&-1)%1&%71$/./+*%0"'(8*%A'2,%1771$/.*%.1%."'.%1&%."*%&-1)%1&%2*8'./+* 0"'(8*C:%;1(%"1-*$%'2,%*-*0.(12$%,/&$/28%/2%/2.(/2$/0%$/-/0123%.57/0'-%+'-#*$%&1(%."*%,/&$/12 012$.'2.$%'(*%2"%e%S=%06=`$%%'2,%2#%e%KD%06=`$: G.%."/$%71/2.%."*%(*',*(%/$%7(14'4-5%)12,*(/28%)"*(*%."*%,/&$/12%0#((*2.%/2%."*%$/-/012 4'(%/2%;/8:%K:EA'C%81*$:%G%811,%V#*$./12%'$%)*%'(*%21.%$"1)/28%"1)%."*%(/8".?$/,*%*2,%1&%."* 4'(%/$%0122*0.*,%.1%."*%(*$.%1&%."*%0/(0#/.:%\*%)/--%',,(*$$%."/$%'2,%(*-'.*,%V#*$./12$%/2%,*.'//2%1#(%,/$0#$$/12%1&%."*%"#%F#20./12%/2%-'.*(%$*0./12$:%
Electron concentration, n
Electron diffusion Electron current
x
0
Figure 3.7 >&%."*%*-*0.(12?0120*2.('./12%7(1&/-* $"1)2%/$%*$.'4-/$"*,%/2%'%4'(%1&%$/-/0123%*-*0.(12$ ,/&$*%/2%."*%5%,/(*0./123%8/+/28%(/$*%.1%'2%*-*0.(12? ,/&$/12%0#((*2.%/2%."*%2*8'./+*%?5%,/(*0./12:
Example 3.4 <12$/,*(%'%4'(%1&%$/-/012%/2%)"/0"%'%"1-*%0120*2.('./12%7(1&/-*%,*$0(/4*,%45 " ( 5 ) ! "U %
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3.3 Current Flow in Semiconductors
Solution ," ( 5 ) 9 " % ! " $2 " ?????????????? ,5 "5 ⁄ ;: , ! " $2 " ?????? [ " U % ] ,5
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EXERCISE 3.5 !"*%-/2*'(%*-*0.(12?0120*2.('./12%7(1&/-*%$"1)2%/2%;/8:%OK:D%"'$%4**2%*$.'4-/$"*,%/2%'%7/*0*%1&%$/-/? Sb K 012:% >&% # U ! SU ⁄ 06 % '2,% <% e% S% µ63% &/2,% ."*% *-*0.(12?0#((*2.% ,*2$/.5% /2% 6/0(1% '67*(*$% 7*( 6/0(12%$V#'(*,%AµG`µ6=C:%>&%'%,/&$/12%0#((*2.%1&%S%6G%/$%(*V#/(*,%)"'.%6#$.%."*%0(1$$?$*0./12''(*'%7/2%'%,/(*0./12%7*(7*2,/0#-'(%.1%."*%7'8*C%4*h n(x) n0
0
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x
Figure E3.5
137
138 Chapter 3 Semiconductors
3.3.3 Relationship between D and m G%$/67-*%4#.%71)*(-%(*-'./12$"/7%./*$%."*%,/&$/12%012$.'2.%)/."%."*%614/-/.53 2" 2# ?????? ! ?????? ! = )
µ#
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)"*(*% = ) ! () ⁄ $ :%!"*%7'('6*.*(% = ) %/$%921)2%'$%."*%#/$&,'.)1-.#'%$:%G.%(116%.*67*('? .#(*3%) ! KUU%Y%'2,% = ) %%e%=D:T %6P:%\*%)/--%*201#2.*(% = ) %(*7*'.*,-5%."(1#8"1#.%."/$%4119: !"*%(*-'./12$"/7%/2%OV:%AK:=SC%/$%921)2%'$%."*%9!"5#$!")&$.'#!-"5/!0:
EXERCISE =
3.6 i$*%."*% O/2$.*/2% (*-'./12$"/7%.1%&/2,% 2 # %'2,% 2 " %&1(%/2.(/2$/0%$/-/012%#$/28% µ # ! SKDU%06 ⁄ P⋅ $ = '2,% µ " ! BcU%06 ⁄ P ⋅ $ : = Ans. KD%06 `$L%S=:B%06= `$
3.4 The pn Junction with Open-Circuit Terminals (Equilibrium) f'+/28%-*'(2*,%/671(.'2.%$*6/012,#0.1(%0120*7.$3%)*%'(*%21)%(*',5%.1%012$/,*(%1#(%&/($. 7('0./0'-%$*6/012,#0.1(%$.(#0.#(*j."*%"#%F#20./12:%G$%6*2./12*,%7(*+/1#$-53%."*%"#%F#20? ./12%/67-*6*2.$%."*%,/1,*%A<"'7.*(%BC%'2,%7-'5$%."*%,16/2'2.%(1-*%/2%."*%$.(#0.#(*%'2,%17*(? './12%1&%."*%4/71-'(%F#20./12%.('2$/$.1(%AMN!C:%G$%)*--3%#2,*($.'2,/28% "#%F#20./12$%/$%+*(5 /671(.'2.%.1%."*%$.#,5%1&%."*%kRJ;O!%17*('./12%A<"'7.*(%DC:
3.4.1 Physical Structure ;/8#(*% K:c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c3%*@.*(2'-%)/(* 0122*0./12$%'(*%6',*%.1%."*%"%'2,%#%(*8/12$%."(1#8"%6*.'-%A'-#6/2#6C%012.'0.$:%>&%."*%"# F#20./12% /$% #$*,% '$% '% ,/1,*3% ."*$*% 012$./.#.*% ."*% ,/1,*% .*(6/2'-$% '2,% '(*% ."*(*&1(*% -'4*-*, Z'21,*[%'2,%Z0'."1,*[%/2%9**7/28%)/."%,/1,*%.*(6/21-185:K
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3.5 The pn Junction with an Applied Voltage
Metal contact
Anode
Metal contact
p-type silicon
n-type silicon
Cathode
Figure 3.8 J/67-/&/*,%7"5$/0'-%$.(#0.#(*%1&%."*%"#%F#20./12:%AG0.#'-%8*16*.(/*$%'(*%8/+*2%/2%G77*2,/@%G:C G$%."*!"#%F#20./12%/67-*6*2.$%."*%F#20./12%,/1,*3%/.$%.*(6/2'-$%'(*%-'4*-*,%'21,*%'2,%0'."1,*:
3.4.2 Operation with Open-Circuit Terminals ;/8#(*%K:T%$"1)$%'%"#%F#20./12%#2,*(%17*2?0/(0#/.%012,/./12$j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f*(*%'-$13%."* 41#2,%71$/./+*%0"'(8*3%)"/0"%2*#.('-/X*$%."*%0"'(8*%1&%."*%6'F1(/.5%*-*0.(12$3%/$%21.%$"1)2 /2%1(,*(%.1%9**7%."*%,/'8('6%$/67-*:%!"*%#?.57*%6'.*(/'-%'-$1%012.'/2$%6/21(/.5%"1-*$%8*2*(? '.*,%45%."*(6'-%/12/X'./12%4#.%21.%$"1)2%/2%."*%,/'8('6: The Diffusion Current ID M*0'#$*%."*%0120*2.('./12%1&%"1-*$%/$%"/8"%/2%."*%"%(*8/12%'2, -1)%/2%."*%#%(*8/123%"1-*$%,/&$*%'0(1$$%."*%F#20./12%&(16%."*%"%$/,*%.1%."*%#%$/,*L%$/6/-'(-53 *-*0.(12$%,/&$*%'0(1$$%."*%F#20./12%&(16%."*%#%$/,*%.1%."*%"%$/,*:%!"*$*%.)1%0#((*2.%01671? 2*2.$%',,%.18*."*(%.1%&1(6%."*%,/&$/12%0#((*2.%62 3%)"1$*%,/(*0./12%/$%&(16%."*%"%$/,*%.1%."* #%$/,*3%'$%/2,/0'.*,%/2%;/8:%K:T: The Depletion Region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j1(3%$/67-53%($0.$#!-")&$%!-"j/$%'-$1%0'--*,%."*%50'*$:*/'&%$ &$%!-":% !"*% 0"'(8*$% 12% 41."% $/,*$% 1&% ."*% ,*7-*./12% (*8/12% 0'#$*% '2% *-*0.(/0% &/*-,% &% .1% 4*
139
140 Chapter 3 Semiconductors
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3.5 The pn Junction with an Applied Voltage 141
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62 = 6A B
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142 Chapter 3 Semiconductors
ID IS " " " " " "
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3.5 The pn Junction with an Applied Voltage 143
,*7-*./12%(*8/12%/2%."*%"%$/,*%45% 5 " %'2,%/2%."*%#%$/,*%45%5#3%)*%0'2%*@7(*$$%."*%6'82/.#,*%1& ."*%0"'(8*%12%."*%#%$/,*%1&%."*%F#20./12%'$ AK:=KC
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144 Chapter 3 Semiconductors
Example 3.5 <12$/,*(%'%"#%F#20./12%/2%*V#/-/4(/#6%'.%(116%.*67*('.#(*%A)%e%KUU%YC%&1(%)"/0"%."*%,17/28%0120*2? Sc K SE K .('./12$%'(*% 1 3 % ! SU ⁄ 06 %'2,% 1 2 % ! SU ⁄ 06 %'2,%."*%0(1$$?$*0./12'-%'(*'%3%e%SU]B%06=:%<'-0#-'.* SU K "" 3% #"U3% ## 3% "#U3% =U3%<3% 5#3% 5" 3%'2,% B 9 :%i$*% # + % ! S:D × SU ⁄ 06 : Solution
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3.5 The pn Junction with an Applied Voltage 145
EXERCISES 3.7 J"1)%."'. S $ = U % ! ??? ???? = ε0
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146 Chapter 3 Semiconductors
3.5 The pn Junction with an Applied Voltage
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3.5.2 The Current–Voltage Relationship of the Junction \*%'(*%21)%(*',5%.1%&/2,%'2%'2'-5./0'-%*@7(*$$/12%."'.%,*$0(/4*$%."*%0#((*2.]+1-.'8*%(*-'? ./12$"/7% 1&% ."*% "#% F#20./12:% >2% ."*% &1--1)/28% )*% 012$/,*(% '% F#20./12% 17*('./28% )/."% '
147
148 Chapter 3 Semiconductors &1()'(,%'77-/*,%+1-.'8*%=!'2,%,*(/+*%'2%*@7(*$$/12%&1(%."*%0#((*2.%6!."'.%&-1)$%/2%."*%&1(? )'(,%,/(*0./12%A&(16%"%.1%#C:%f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
= ⁄ =)
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AK:KEC
3.5 The pn Junction with an Applied Voltage
pn , np p region
Depletion region
pn (xn)
n region
Excess concentration pn (x) np (!xp) np(x)
pn0 Thermal equilibrium value
np0 !xp 0
xn
x
Figure 3.12 k/21(/.5?0'((/*(%,/$.(/4#./12%/2%'%&1()'(,?4/'$*,%"#%F#20./12:%>.%/$%'$$#6*,%."'.%."*%"%(*8/12% /$%61(*%"*'+/-5%,17*,%."'2%."*%#%(*8/12L%13%#%12:
G$%*@7*0.*,3% 9 " ( 5 ) %/$%"/8"*$.%'.% 5 ! 5 #3 2 = ⁄ =) 9 " ( 5 # ) ! $ ?????"? " #U ( % " S) ;"
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149
150 Chapter 3 Semiconductors =
=
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Figure 3.13 !"*%"#%F#20./12%6G=%0"'('0.*(/$./0:
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3.5 The pn Junction with an Applied Voltage
Example 3.6 Sc
K
SE
K
;1(% ."*% "#! F#20./12% 012$/,*(*,% /2% O@'67-*% K:D% &1(% )"/0"% 1 3 % ! SU ⁄ 06 3% 1 2 % ! SU ⁄ 06 3 "B = SU K = 3% ! SU 06 3% # + % ! S:D × SU ⁄ 06 3%-*.% ; " % ! D %µ63% ; # ! SU %µ63% 2 " %A/2%."*%#%(*8/12C%e SU%06 ⁄ P : $3 = '2,% 2 # %A/2%."*%"%(*8/12C% ! Sc%06 ⁄ P: $:%!"*%"#%F#20./12%/$%&1()'(,%4/'$*,%'2,%012,#0./28%'%0#((*2. 6%e%U:S%6G:%<'-0#-'.*H%A'C% 6 A L%A4C%."*%&1()'(,?4/'$%+1-.'8*%=L%'2,%A0C%."*%016712*2.%1&%."*%0#((*2.%6 ,#*%.1%"1-*%/2F*0./12%'2,%."'.%,#*%.1%*-*0.(12%/2F*0./12%'0(1$$%."*%F#20./12: Solution A'C%i$/28%OV:%AK:BSC3%)*%&/2,% 6 A %'$% "B
SU =
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× S:E × SU × ( S:D × SU ) × SU Sc ??????????????????????????????????? ? # ?????????????????????????????????????? ? "B SE "B Sc D × SU × SU SU × SU × SU
6 A% % ! SU
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Sc 6" SU ? = ???? % ! SU ?????? × SU ?????? × ????????? ! S:SS × SU ! SSS 6 # Sc D SU SE
151
152 Chapter 3 Semiconductors
Example 3.6 continued
!"#$%61$.%1&%."*%0#((*2.%/$%012,#0.*,%45%"1-*$%/2F*0.*,%/2.1%."*%#%(*8/12: J7*0/&/0'--53 SSS 6 " % ! ????????? × U:S ! U:UTTS %6G SS= S 6 # % ! ????????? × U:S ! U:UUUT %6G SS=
!"/$%$.'2,$%.1%(*'$123%$/20*%."*%"%6'.*(/'-%"'$%'%,17/28%0120*2.('./12%SUU%./6*$%."'.%1&%."*%#%6'.*(/'-:
EXERCISES 3.10 J"1)%."'.%/&% 1 3 # 1 2 3% = 2" ? 6 A% ! 3$# + ???????????? ;" 12
3.11 ;1(%."*%"#%F#20./12%/2%O@'67-*%K:E3%&/2,%."*%+'-#*%1&% 6 A %'2,%."'.%1&%."*%0#((*2.%6%'.%=%e%U:EUD%P%A$'6* +1-.'8*%&1#2,%/2%O@'67-*%K:E%'.%'%0#((*2.%6%e%U:S%6GC%/&% 1 2 %/$%(*,#0*,%45%'%&'0.1(%1&%=: " SB Ans. S:BE × SU %GL%U:=%6G 3.12 ;1(%."*%"#%F#20./12%012$/,*(*,%/2%O@'67-*$%K:D%'2,%K:E3%&/2,%."*%)/,."%1&%."*%,*7-*./12%(*8/12%<%01(? (*$712,/28%.1%."*%&1()'(,?4/'$%+1-.'8*%&1#2,%/2%O@'67-*%K:E:%AI+#/H%i$*%."*%&1(6#-'%/2%OV: AK:KSC )/."% = E %(*7-'0*,%)/."% " = F :C Ans. U:SEE%µ6 3.13 ;1(%."*%"#%F#20./12%012$/,*(*,%/2%O@'67-*$%K:D%'2,%K:E3%&/2,%."*%)/,."%1&%."*%,*7-*./12%(*8/12%<%'2, ."*%0"'(8*%$.1(*,%/2%."*%,*7-*./12%(*8/12% B 9 %)"*2%'%=?P%(*+*($*%4/'$%/$%'77-/*,:%G-$1%&/2,%."*%+'-#* 1&%."*%(*+*($*%0#((*2.%6: " SD Ans. U:EUc%µ6L%T:EK%7
3.5.3 Reverse Breakdown !"*% ,*$0(/7./12% 1&% ."*% 17*('./12% 1&% ."*% "#% F#20./12% /2% ."*% (*+*($*% ,/(*0./123% '2,% ."*% 6 " = (*-'./12$"/7% 1&% ."*% F#20./12% /2% OV:% AK:BUC3% /2,/0'.*% ."'.% '.% '% (*+*($*?4/'$% +1-.'8*% ]=3% )/." = # = ) 3%."*%(*+*($*%0#((*2.%."'.%&-1)$%'0(1$$%."*%F#20./12%/$%'77(1@/6'.*-5%*V#'-%.1% 6 A !'2, ."#$%/$% +*(5% $6'--:% f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
3.5 The pn Junction with an Applied Voltage 153
I
!VZ 0
V
Figure 3.14 !"*%6?=%0"'('0.*(/$./0%1&%."*%"#%F#20./12%$"1)/28%."*%('7/,%/20(*'$*%/2%(*+*($*%0#((*2.%/2%."* 4(*'9,1)2%(*8/12:
-/6/.*,%45%."*%*@.*(2'-%0/(0#/.%.1%'%Z$'&*[%+'-#*:%!"*%Z$'&*[%+'-#*%/$%12*%."'.%(*$#-.$%/2%."*%-/6/? .'./12%1&%."*%71)*(%,/$$/7'.*,%/2%."*%F#20./12%.1%'%$'&*3%'--1)'4-*%-*+*-: !"*(*%'(*%.)1%71$$/4-*%6*0"'2/$6$%&1(%"#%F#20./12%4(*'9,1)2H%."*%>$"$&)$33$*#b%'2,%."* '1'.'"*/$)$33$*#:%>&%'%"#%F#20./12%4(*'9$%,1)2%)/."%'%4(*'9,1)2%+1-.'8*% = H < D %P3%."*%4(*'9? ,1)2%6*0"'2/$6%/$%#$#'--5%."*%X*2*(%*&&*0.:%G+'-'20"*%4(*'9,1)2%100#($%)"*2% = H %/$%8(*'.*( ."'2%'77(1@/6'.*-5%b%P:%;1(%F#20./12$%."'.%4(*'9%,1)2%4*.)**2%D%P%'2,%b%P3%."*%4(*'9,1)2 6*0"'2/$6%0'2%4*%*/."*(%."*%X*2*(%1(%."*%'+'-'20"*%*&&*0.%1(%'%0164/2'./12%1&%."*%.)1: n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a'6*,%'&.*(%'2%*'(-5%)1(9*(%/2%."*%'(*':%a1.*%."'.%."*%$#4$0(/7.!H%/2%=H%,*21.*$%J%#%7:%\*%)/--%#$*%=H .1%,*21.*%."*%4(*'9,1)2%+1-.'8*%)"*."*(%."*%4(*'9,1)2%6*0"'2/$6%/$%."*%X*2*(%*&&*0.%1(%."*%'+'-'20"* *&&*0.: b%
154 Chapter 3 Semiconductors G$%)/--%4*%$**2%/2%<"'7.*(%B3%$16*%"#!F#20./12%,/1,*$%'(*%&'4(/0'.*,%.1%17*('.*%$7*0/&/? 0'--5%/2%."*%4(*'9,1)2%(*8/123%)"*(*%#$*%/$%6',*%1&%."*%2*'(-5%012$.'2.%+1-.'8*%=H:
3.6 Capacitive Effects in the pn Junction !"*(*%'(*%.)1%0"'(8*%$.1('8*%6*0"'2/$6$%/2%."*%"#%F#20./12:%R2*%/$%'$$10/'.*,%)/."%."*%0"'(8* $.1(*,% /2% ."*% ,*7-*./12% (*8/123% '2,% ."*% 1."*(% '$$10/'.*,% )/."% ."*% 6/21(/.5% 0'((/*(% 0"'(8* $.1(*,%/2%."*%#%'2,%"%6'.*(/'-$%'$%'%(*$#-.%1&%."*%0120*2.('./12%7(1&/-*$%*$.'4-/$"*,%45%%0'(? (/*(%/2F*0./12:%\"/-*%."*%&/($.%/$%*'$/*(%.1%$**%)"*2%."*%"#%F#20./12%/$%(*+*($*%4/'$*,3%."*%$*0? 12,%/$%/2%*&&*0.%12-5%)"*2%."*%F#20./12%/$%&1()'(,%4/'$*,:
3.6.1 Depletion or Junction Capacitance \"*2%'%"#%F#20./12%/$%(*+*($*%4/'$*,%)/."%'%+1-.'8*%=E 3%."*%0"'(8*%$.1(*,%12%*/."*(%$/,*%1& ."*%,*7-*./12%(*8/12%/$%8/+*2%45%OV:%AK:K=C3 13 12 ? ( = # =E ) B 9 %% ! 3 =ε 0 $ ??????????????????? 13 # 12 U
!"#$3%&1(%'%8/+*2%"#%F#20./123 B9 ! α =U # =E
AK:B=C
13 12 ? α% ! 3 =ε 0 $ ??????????????????? 13 # 12
AK:BKC
Charge stored in depletion layer, QJ
)"*(*% α %/$%8/+*2%45
Slope $ CJ
Q Bias point
0
VQ
Reverse voltage,VR
Figure 3.15 !"*% 0"'(8*% $.1(*,% 12% */."*(% $/,*% 1&% ."*% ,*7-*./12% -'5*(% '$% '% ./12% 1&% ."*% (*+*($* +1-.'8* =E:
3.6 Capacitive Effects in the pn Junction 155
!"#$% B 9 %/$%212-/2*'(-5%(*-'.*,%.1%=E 3%'$%$"1)2%/2%;/8:%AK:SDC:%!"/$%212-/2*'(%(*-'./12$"/7 6'9*$%/.%,/&&/0#-.%.1%,*&/2*%'%0'7'0/.'20*%."'.%'001#2.$%&1(%."*%2**,%.1%0"'28*% B 9 %)"*2*+*( = E %/$%0"'28*,:%\*%0'23%"1)*+*(3%'$$#6*%."'.%."*%F#20./12%/$%17*('./28%'.%'%71/2.%$#0"%'$%B3 '$%/2,/0'.*,%/2%;/8:%K:SD3%'2,%,*&/2*%'%0'7'0/.'20*% L M %."'.%(*-'.*$%."*%0"'28*%/2%."*%0"'(8* B 9 %.1%'%0"'28*%/2%."*%+1-.'8*% = E 3 ,B L M%% ! ?????????9 ,= E
AK:BBC = E != B
!"/$% /20(*6*2.'-?0'7'0/.'20*% '77(1'0"% .#(2$% 1#.% .1% 4*% V#/.*% #$*-% /2% *-*0.(12/0% 0/(0#/. ,*$/823%'$%)*%$"'--%$**%."(1#8"1#.%."/$%4119: i$/28%OV:%AK:BBC%.18*."*(%)/."%OV:%AK:B=C%5/*-,$% α L M % ! ?????????????????????????? = =U # =E
AK:BDC
!"*%+'-#*%1&% L M %'.%X*(1%(*+*($*?4/'$%0'2%4*%14.'/2*,%&(16%OV: AK:BDC%'$ α ? L MU ! ???????????? = =U )"/0"%*2'4-*$%#$%.1%*@7(*$$% L M %'
%$L MU L M ! ???????????????????? = S # ?????E? =U
AK:BEC
AK:BbC
)"*(*% L MU %/$%8/+*2%45%OV:%AK:BEC%1(%'-.*(2'./+*-5%/&%)*%$#4$./.#.*%&1(% α %&(16%OV:%AK:BKC%45 L MU ! 3
ε0 $ ??????? =
13 12 ??????????????????? ? 13 # 12
S ?????? =U
AK:BcC
M*&1(*%-*'+/28%."*%$#4F*0.%1&%,*7-*./12?(*8/12%1(%F#20./12%0'7'0/.'20*%)*%71/2.%1#.%."'.%/2 ."*%"#%F#20./12%)*%"'+*%4**2%$.#,5/283%."*%,17/28%0120*2.('./12%/$%6',*%.1%0"'28*%'4(#7.-5 '.%."*%F#20./12%41#2,'(5:%J#0"%'%F#20./12%/$%921)2%'$%'2%'2&+0#)6+"*#!-":%!"*(*%/$%'21."*( .57*%1&%"#%F#20./12%/2%)"/0"%."*%0'((/*(%0120*2.('./12%/$%6',*%.1%0"'28*%8(',#'--5%&(16%12* $/,*%1&%."*%F#20./12%.1%."*%1."*(:%!1%'--1)%&1(%$#0"%'%%&'($()6+"*#!-"3%."*%&1(6#-'%&1(%."* F#20./12%0'7'0/.'20*%AOV:%K:BbC%0'2%4*%)(/..*2%/2%."*%61(*%8*2*('-%&1(6 L MU L M ! ???????????????????????? ? =E K S # ?????? =U
AK:BTC
)"*(*%K%/$%'%012$.'2.%0'--*,%."*%%&'(!"%)*-$33!*!$"#3%)"1$*%+'-#*%('28*$%&(16%S`K%.1%S`= ,*7*2,/28%12%."*%6'22*(%/2%)"/0"%."*%0120*2.('./12%0"'28*$%&(16%."*%"%.1%."*%#%$/,*:%
EXERCISE 3.12 ;1(%."*%"#%F#20./12%012$/,*(*,%/2%O@'67-*$%K:D%'2,%K:E3%&/2,% L MU %'2,% L M %'.% = E % ! = %P:%_*0'--%."'. Sc K SE K "B = = U % ! U:cSB %P3% 1 3 % ! SU ⁄ 06 3% 1 2 % ! SU ⁄ 06 %'2,% 3% ! SU 06 : Ans. K:=%7;L%S:b%7;
156 Chapter 3 Semiconductors
3.6.2 Diffusion Capacitance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c B " ! 3$ × $"',*,%'(*'%#2,*(%."*% " # ( 5 ) %0#(+* ! 3$ [ " # ( 5 # ) " " #U ]; "
$#4$./.#./28%&1(% " # ( 5 # ) %&(16%OV:%AK:KKC%'2,%#$/28%OV:%AK:KbC%*2'4-*$%#$%.1%*@7(*$$% B " %'$ =
;" B " % ! ?????? 6 " 2"
AK:DUC
=
!"*%&'0.1(% ( ; " ⁄ 2 " ) %."'.%(*-'.*$% B " %.1% 6 " %/$%'%#$*-%,*+/0*%7'('6*.*(%."'.%"'$%."*%,/6*2$/12 1&%./6*%A$C%'2,%/$%,*21.*,% τ " =
;" τ " % ! ?????? 2"
AK:DSC
B" ! τ" 6"
AK:D=C
!"#$3 !"*%./6*%012$.'2.% τ "%/$%921)2%'$%."*%*@0*$$%,!"-&!#4)*'&&!$&)7/-.$8).!3$#!,$:%6/!+0!/@% .4%7.'%!/+K%!+/!/.(%0!8-7!.!@->%!+#M%?/%,!+#/-!/@%!#!7%'+-#!/-!7%?-KD+#%!N+/@!.!K.M-7+/O!%>%?P /7-#:%!"/$%,*&/2/./12%1&% τ "%/67-/*$%."'.%."*%*2./(*%0"'(8*% B "%,/$'77*'($%'2,%"'$%.1%4*%(*7-*2? /$"*,%*+*(5%τ "%$*012,$:%!"*%0#((*2.%."'.%'00167-/$"*$%."*%(*7-*2/$"/28%/$% 6 " ! B " ⁄ τ " :%!"/$%/$ '2%'-.*(2'.*%,*(/+'./12%&1(%OV:%AK:D=C: G%(*-'./12$"/7%$/6/-'(%.1%."'.%/2%OV:%AK:D=C%0'2%4*%,*+*-17*,%&1(%."*%*-*0.(12%0"'(8*%$.1(*,%/2 ."*%"%(*8/123 B# % ! τ# 6#
AK:DKC
)"*(*% τ # %/$%."*%*-*0.(12%-/&*./6*%/2%."*%"%(*8/12:%!"*%.1.'-%*@0*$$%6/21(/.5%0'((/*(%0"'(8*%0'2 4*%14.'/2*,%45%',,/28%.18*."*(% B " %'2,% B # 3 B% ! τ " 6 " # τ # 6 #
AK:DBC
!"/$%0"'(8*%0'2%4*%*@7(*$$*,%/2%.*(6$%1&%."*%,/1,*%0#((*2.% 6% ! 6 " # 6 # %'$% B% ! τ ) 6
AK:DDC
)"*(*% τ ) %/$%0'--*,%."*%,$'")#&'"5!#)#!,$%1&%."*%F#20./12:%R4+/1#$-53% τ ) %/$%(*-'.*,%.1% τ " %'2, τ #:%;#(."*(61(*3%&1(%61$.%7('0./0'-%,*+/0*$3%12*%$/,*%1&%."*%F#20./12%/$%6#0"%61(*%"*'+/-5 ,17*,% ."'2% ."*% 1."*(:% ;1(% /2$.'20*3% /&% 1 3 # 1 2 3% 12*% 0'2% $"1)% ."'.% 6 " # 6 # 3% 6 ! 6 " 3 B " # B # 3%B ! B " 3%'2,%."#$% τ )% ! τ " :% _*0'--%."'.%."*%'(*'%#2,*(%'2%*@712*2./'-%0#(+*% 3%
c
"5 ⁄ *
%/$%*V#'-%.1%3*:
3.6 Capacitive Effects in the pn Junction 157
;1(% $6'--% 0"'28*$% '(1#2,% '% 4/'$% 71/2.3% )*% 0'2% ,*&/2*% '2% !"*&$,$"#'.) (!33+5!-" *'0'*!#'"*$% L , %'$% ,B AK:DEC L , % ! ??????? ,= '2,%0'2%$"1)%."'. τ L , % ! ??????)? 6 =)
AK:DbC
)"*(*%6!/$%."*%&1()'(,?4/'$%0#((*2.:%a1.*%."'.% L , %/$%,/(*0.-5%7(171(./12'-%.1%."*%&1()'(,%0#(? (*2.%6%'2,%."#$%/$%2*8-/8/4-5%$6'--%)"*2%."*%,/1,*%/$%(*+*($*%4/'$*,:%G-$1%21.*%."'.%.1%9**7 L , %$6'--3%."*%.('2$/.%./6*% τ ) %6#$.%4*%6',*%$6'--3%'2%/671(.'2.%(*V#/(*6*2.%&1(%'%"#!F#20? ./12%/2.*2,*,%&1(%"/8"?$7**,%1(%"/8"?&(*V#*205%17*('./12:
EXERCISES 3.15
i$*%."*%,*&/2/./12%1&% L , %/2%OV:%AK:DEC%.1%,*(/+*%."*%*@7(*$$/12%/2%OV:%AK:DbC%45%6*'2$%1&%OV$:%AK:DDC '2,%AK:BUC:
3.16
;1(%."*%"#%F#20./12%012$/,*(*,%/2%O@'67-*$%K:D%'2,%K:E%&1(%)"/0"% 2 " % ! SU%06 ⁄ P ⋅ $ 3%'2,% ; " ! D µ63%&/2,% τ " %'2,% L , %'.%'%&1()'(,?4/'$%0#((*2.%1&%U:S%6G:%_*0'--%."'.%&1(%."/$%F#20./123% 6 " ! 6 :
=
Ans. =D%2$L%TE:D%7;
158 Chapter 3 Semiconductors
Summary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f1)*+*(3% .)1% *V#'-% '2,
1771$/.*% 0#((*2.$3% 6 2%'2,% 6 A 3% &-1)% '0(1$$% ."*% F#20./123 '2,%*V#/-/4(/#6%/$%6'/2.'/2*,%45%'%4#/-.?/2%+1-.'8*% = U ."'.%,*+*-17$%'0(1$$%."*%F#20./123%)/."%."*%#%$/,*%71$/./+* (*-'./+*% .1% ."*% "% $/,*:% a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
3.6 Capacitive Effects in the pn Junction
159
Table 3.1 Summary of Important Equations P'-#*$%1&%<12$.'2.$%'2,%r'('6*.*($% A&1(%>2.(/2$/0%J/%'.%)%e%KUU%YC
q#'2./.5
_*-'./12$"/7
<'((/*(%0120*2.('./12%/2% /2.(/2$/0%$/-/012%A06]KC
# + = *)
I/&$/12%0#((*2.% ,*2$/.5%AG`06=C
," 9 " = " $2 " ?????? ,5
K`= " & ' ⁄ =()
%
,# 9 # = $2 # ?????? ,5
* = &' = ( = #+ =
"K
SD
b:K × SU 06 Y S:S=%*P "D c:E= × SU *P`Y SU K S:D × SU `06
$ = S:EU × SU
" ST
" K`=
%01#-164
=
2 " = S=%06 `$ =
2 # = KB%06 `$ =
I(/&.%0#((*2.%,*2$/.5% AG`06=C
9 ,7+8/ = $ ( " µ " + # µ # )&
_*$/$./+/.5%AΩ⋅06C
ρ = S ⁄ [ $ ( " µ" + # µ# ) ]
µ"%'2,%µ#%,*0(*'$*%)/."%."*%/20(*'$*
_*-'./12$"/7%4*.)**2% 614/-/.5%'2,%,/&$/+/.5
2 2# ?????? = ?????"? = = )
= ) = () ⁄ $ ! =D:c%6P
<'((/*(%0120*2.('./12%/2% #?.57*%$/-/012%A06%]K C
# #U %! 1 2
<'((/*(%0120*2.('./12%/2% "?.57*%$/-/012%A06%%]K C
" "U% ! 1 3
N#20./12%4#/-.?/2% +1-.'8*%APC
13 12 ? = U = = ) -2 ????????????? = #+
\/,."%1&%,*7-*./12% (*8/12%A06C
5# 1 ???? = ??????3? 5" 12
=
µ # = SKDU%06 `P⋅$
µ#
µ" =
=
# "U = # + ⁄ 1 3
=
;1()'(,%0#((*2.%AGC
/2%,17/28%0120*2.('./12
" #U = # + ⁄ 1 2
ε 0 = SS:b ε U
< = 5# + 5"
<"'(8*%$.1(*,%/2%,*7-*./12% -'5*(%A01#-164C
µ " = BcU%06 `P⋅$
= ε0 S S? ??????? ?????? + ?????? ( =U + =E ) $ 1 3 12
13 12 ? 3< B 9 = $ ??????????????????? 13 + 12 6 = 6" + 6# = ⁄ =) = 2" 6 " = 3$ # + ????????????? ( % " S) ;" 12 =⁄= = 2# ? (% ) " S) 6 # = 3$ # + ??????????? ;# 13
J'.#('./12%0#((*2.%AGC
2" 2# = ? + ??????????? ? 6 A = 3$ # + ???????????? ;" 12 ;# 13
6?=%_*-'./12$"/7
6 ! 6A ( %
= ⁄ =)
" S)
ε U = c:cDB% × SU
" SB
%;`06
160 Chapter 3 Semiconductors
Table 3.1 continued q#'2./.5
_*-'./12$"/7
k/21(/.5?0'((/*(% -/&*./6*%A$C
τ " = ;" ⁄ 2"
k/21(/.5?0'((/*(% 0"'(8*%$.1('8*% A01#-164C
B" = τ" 6"
I*7-*./12%0'7'0/.'20*%A;C
=
P'-#*$%1&%<12$.'2.$%'2,%r'('6*.*($% A&1(%>2.(/2$/0%J/%'.%)%e%KUU%YC B
τ ", τ # = S%2$%.1%SU %2$ B# = τ# 6#
B = B" + B# = τ) 6 L MU = 3
ε0 $ ??????? =
13 12 S ??????????????????? ? ????? 13 # 12 =U
= L M = L MU %% S + ?????E? =U I/&$/12% 0'7'0/.'20*%A;C
; ", ; # = S%µ6%.1%SUU%µ6
=
τ# = ;# ⁄ 2#
K
S S K = ??? %.1% ??? K =
τ
L , = ?????)? 6 =)
PROBLEMS
r(14-*6$%'(*%6'(9*,%)/."%'$.*(/$9$%.1%,*$0(/4*%."*/(%,*8(** 1&%,/&&/0#-.5:%I/&&/0#-.%7(14-*6$%'(*%6'(9*,%)/."%'2%'$.*(/$9 AsCL% 61(*% ,/&&/0#-.% 7(14-*6$% )/."% .)1% '$.*(/$9$% AssCL% '2, +*(5% 0"'--*28/28% '2,`1(% ./6*?012$#6/28% 7(14-*6$% )/." ."(**%'$.*(/$9$%AsssC:%G-$13%/&%/2%."*%&1--1)/28%7(14-*6$%."* 2**,% '(/$*$% &1(% ."*% +'-#*$% 1&% 7'(./0#-'(% 7'('6*.*($% 1( 7"5$/0'-% 012$.'2.$% ."'.% '(*% 21.% $.'.*,3% 7-*'$*% 012$#-. !'4-* K:S:
Section 3.1: Intrinsic Semiconductors 3.1 ;/2,% +'-#*$% 1&% ."*% /2.(/2$/0% 0'((/*(% 0120*2.('./12% # + &1(% $/-/012% '.% " bU°<3% U° <3% =U°<3% SUU°<3% '2,% S=D°<:% G. *'0"% .*67*('.#(*3% )"'.% &('0./12% 1&% ."*% '.16$% /$% /12/X*,h == _*0'--% ."'.% '% $/-/012% 0(5$.'-% "'$% '77(1@/6'.*-5% D × SU K '.16$`06 :% 3.2 <'-0#-'.*% ."*% +'-#*% 1&% # + % &1(% 8'--/#6% '($*2/,* SB A^'G$C% '.% )% e% KUU% Y:% !"*% 012$.'2.% *% ! K:DE × SU "K "K ⁄ = ( 06 Y )%'2,%."*%4'2,8'7%+1-.'8*%&' e S:B=%*P:
Section 3.2: Doped Semiconductors 3.3
;1(%'%"?.57*%$/-/012%/2%)"/0"%."*%,17'2.%0120*2.('./12
1 3 % ! SU Sc ⁄ 06 K3% &/2,% ."*% "1-*% '2,% *-*0.(12% 0120*2.('./12$
'.%)%e%KUU%Y:
3.4 ;1(% '% $/-/012% 0(5$.'-% ,17*,% )/."% 7"1$7"1(#$3% )"'. 6#$.% 1 2 % 4*% /&% '.% )% e% KUU% Y% ."*% "1-*% 0120*2.('./12% ,(17$ b 4*-1)%."*%/2.(/2$/0%-*+*-%45%'%&'0.1(%1&% SU h 3.5 >2% '% 7"1$7"1(#$?,17*,% $/-/012% -'5*(% )/."% /67#(/.5 SE K 0120*2.('./12% 1&%SU ⁄ 06 3% &/2,% ."*% "1-*% '2,% *-*0.(12% 012? 0*2.('./12$%'.% =b°< %'2,%S=D°<:
Section 3.3: Current Flow in Semiconductors 3.6 G% 51#28% ,*$/82*(3% '/6/28% .1% ,*+*-17% /2.#/./12% 012? 0*(2/28%012,#0./28%7'."$%)/."/2%'2%/2.*8('.*,%0/(0#/.3%*@'6? /2*$%."*%*2,?.1?*2,%(*$/$.'20*%1&%'%0122*0./28%4'(%SU%µ6 -1283%K%µ6%)/,*3%'2,%S%µ6%."/093%6',*%1&%+'(/1#$%6'.*(/'-$: !"*%,*$/82*(%012$/,*($H
Problems
SE
K
Sc
K
SE
K
A4C%#?,17*,%$/-/012%)/."% 1 2 ! SU ⁄ 06 A0C%#?,17*,%$/-/012%)/."% 1 2 ! SU ⁄ 06 A,C%"?,17*,%$/-/012%)/."% 1 3 ! SU ⁄ 06
pn(x)
108 pn0
CHAPTER 3 P R O B L E M S
A'C%/2.(/2$/0%$/-/012
161
n region
A*C%'-#6/2#6%)/."%(*$/$./+/.5%1&%=:c% µΩ : 06 ;/2,%."*%(*$/$.'20*%/2%*'0"%0'$*:%;1(%/2.(/2$/0%$/-/0123%#$*%."* ,'.'% /2% !'4-*% K:S:% ;1(% ,17*,% $/-/0123% '$$#6* = µ #% ! =:D µ " % ! S=UU%06 ⁄ P:$:%A_*0'--%."'.% E ! ρ ; ⁄ 3 C 3.7 <12.('$.%."*%*-*0.(12%'2,%"1-*%,(/&.%+*-10/./*$%."(1#8" '%SU?µ6%-'5*(%1&%/2.(/2$/0%$/-/012%'0(1$$%)"/0"%'%+1-.'8*%1& = D P% /$% /671$*,:% Q*.% µ # ! SKDU %06 ⁄ P:$% '2, = µ " ! BcU%06 ⁄ P:$: 3.8 ;/2,%."*%0#((*2.%."'.%&-1)$%/2%'%$/-/012%4'(%1&%SU?µ6 -*28."% "'+/28% '% D?µ6 × B?µ6 % 0(1$$% $*0./12% '2,% "'+/28 D K SD K &(**%*-*0.(12%'2,%"1-*%,*2$/./*$%1&% SU ⁄ %06 %'2,%SU ⁄ 06 3 (*$7*0./+*-53% )"*2% '% S% P% /$% '77-/*,% *2,?.1?*2,:% i$* = = µ # ! S=UU%06 ⁄ P:$%'2,% µ " ! DUU%06 ⁄ P:$: 3.9 >2% '% SU?µ6% -128% 4'(% 1&% ,121(?,17*,% $/-/0123% )"'. ,121(%0120*2.('./12%/$%2**,*,%.1%(*'-/X*%'%0#((*2.%,*2$/.5%1& = S%6G ⁄ µ6 %/2%(*$712$*%.1%'2%'77-/*,%+1-.'8*%1&%S%P:%A1-/%H G-."1#8"%."*%0'((/*(%614/-/./*$%0"'28*%)/."%,17/28%0120*2? .('./123% '$% '% &/($.% '77(1@/6'./12% 51#% 6'5% '$$#6*% µ # % .1% 4* 012$.'2.% '2,% #$*% ."*% +'-#*% &1(% /2.(/2$/0% $/-/0123 = SKDU%06 ⁄ P:$C: 3.10 f1-*$% '(*% 4*/28% $.*',/-5% /2F*0.*,% /2.1% '% (*8/12% 1&% #? .57*%$/-/012%A0122*0.*,%.1%1."*(%,*+/0*$3%."*%,*.'/-$%1&%)"/0" '(*%21.%/671(.'2.%&1(%."/$%V#*$./12C:%>2%."*%$.*',5%$.'.*3%."* *@0*$$?"1-*% 0120*2.('./12% 7(1&/-*% $"1)2% /2% ;/8:% rK:SU% /$ *$.'4-/$"*,% /2% ."*% #?.57*% $/-/012% (*8/12:% f*(*% Z*@0*$$[ 6*'2$% 1+*(% '2,% '41+*% ."*% ."*(6'-?*V#/-/4(/#6% 0120*2.('? ./12% A/2% ."*% '4$*20*% 1&% "1-*% /2F*0./12C3% ,*21.*,% " #U:% >& 1 2 ! SU SE ⁄ 06 K3% # + ! S:D × SU SU ⁄ 06 K 3% 2 # ! S=%06 = ⁄ $3 '2,%
Doping Concentration (carriers/cm3) >2.(/2$/0
SU
SE
SU
Sb
SU
Sc
Table P3.11
mn (cm2/V·s)
pn0
0
W
x
Figure P3.10
3.11 M1."%."*%0'((/*(% 614/-/.5% '2,% ,/&$/+/.5% ,*0(*'$*% '$ ."*% ,17/28% 0120*2.('./12% 1&% $/-/012% /$% /20(*'$*,:% !"*% .'4-* 4*-1)%7(1+/,*$%'%&*)%,'.'%71/2.$%&1(% µ #%'2,%µ "%+*($#$%,17? /28%0120*2.('./12:%i$*%."*%O/2$.*/2%(*-'./12$"/7%.1%14.'/2%."* 01((*$712,/28%+'-#*$%&1(% 2 # %'2,% 2 ":
Section 3.4: The pn Junction with Open-Circuit Terminals (Equilibrium) 3.12 <'-0#-'.*% ."*% 4#/-.?/2% +1-.'8*% 1&% '% F#20./12% /2% )"/0" SE ."*%"%'2,%#%(*8/12$%'(*%,17*,%*V#'--5%)/."% SU %'.16$`06K: SU K G$$#6*% # + % ! S:D × SU ⁄ 06 :%\/."%."*%.*(6/2'-$%-*&.%17*23 )"'.%/$%."*%)/,."%1&%."*%,*7-*./12%(*8/123%'2,%"1)%&'(%,1*$%/. *@.*2,%/2.1%."*%"%'2,%#%(*8/12$h%>&%."*%0(1$$?$*0./12'-%'(*'%1& ."*% F#20./12% /$% SUU% µ6=3% &/2,% ."*% 6'82/.#,*% 1&% ."*% 0"'(8* $.1(*,%12%*/."*(%$/,*%1&%."*%F#20./12: 3.13 >&3%&1(%'%7'(./0#-'(%F#20./123%."*%'00*7.1(%0120*2.('? ./12%/$% SU SE⁄ 06 K %'2,%."*%,121(%0120*2.('./12%/$%SU SD⁄ 06 K3 &/2,% ."*% F#20./12% 4#/-.?/2% +1-.'8*:% G$$#6*% #+ e SU K S:D × SU ⁄ 06 :% G-$13% &/2,% ."*% )/,."% 1&% ."*% ,*7-*./12 (*8/12% A
mp (cm2/V·s)
SKDU
BcU
SSUU
BUU
bUU
=EU
KEU
SDU
Dn (cm2/s)
Dp (cm2/s)
CHAPTER 3 P R O B L E M S
162 Chapter 3 Semiconductors 3.14 O$./6'.*%."*%.1.'-%0"'(8*%$.1(*,%/2%'%U:S?µ6%,*7-*./12 -'5*(%12%12*%$/,*%1&%'% SU?µ6 × SU?µ6 %F#20./12:%!"*%,17? SE K /28%0120*2.('./12%12%."'.%$/,*%1&%."*%F#20./12%/$% SU ⁄ 06 : 3.15 >2%'%"#%F#20./12%&1(%)"/0"% 1 3 # 1 2 3%'2,%."*%,*7-*? ./12%-'5*(%*@/$.$%61$.-5%12%."*%$"'--1)-5%,17*,%$/,*%)/."%<%e SE K U:K%µ63%&/2,% = U %/&% 1 2 ! SU ⁄ 06 :%G-$1%0'-0#-'.*% B 9 : 3.16 M5% "1)% 6#0"% ,1*$% = U % 0"'28*% /&% 1 3 % 1(% 1 2 % /$ /20(*'$*,%45%'%&'0.1(%1&%SUh
l
3.22 G% " # %F#20./12%/$%12*%/2%)"/0"%."*%,17/28%0120*2.('? ./12%/2%."*%"%(*8/12%/$%6#0"%8(*'.*(%."'2%."'.%/2%."*%#!(*8/12: >2%$#0"%'%F#20./123%."*%&1()'(,%0#((*2.%/$%61$.-5%,#*%.1%"1-* /2F*0./12%'0(1$$%."*%F#20./12:%J"1)%."'.% =⁄= = 2" ?(% ) " S) 6 ! 6 " ! 3$# + ???????????? ;" 12 SE
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CHAPTER 3 P R O B L E M S
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163
CHAPTER 4
Diodes
Introduction 4.1
4.5 Rectifier Circuits
165
The Ideal Diode
166
4.2 Terminal Characteristics of Junction Diodes 173 4.3 Modeling the Diode Forward Characteristic 179 4.4 Operation in the Reverse Breakdown Region—Zener Diodes 189
194
4.6 Limiting and Clamping Circuits 4.7 Special Diode Types Summary
215
Problems
216
213
207
IN THIS CHAPTER YOU WILL LEARN 1. The characteristics of the ideal diode and how to analyze and design circuits containing multiple ideal diodes together with resistors and dc sources to realize useful and interesting nonlinear functions. 2. The details of the !"v characteristic of the junction diode (which was derived in Chapter 3) and how to use it to analyze diode circuits operating in the various bias regions: forward, reverse, and breakdown. 3. A simple but effective model of the diode !"v characteristic in the forward direction; the constant-voltage-drop model. 4. A powerful technique for the application and modeling of the diode (and in later chapters, transistors): dc-biasing the diode and modeling its operation for small signals around the dc operating point by means of the small-signal model. 5. The use of a string of forward-biased diodes and of diodes operating in the breakdown region (zener diodes), to provide constant dc voltages (voltage regulators). 6. Application of the diode in the design of rectifier circuits, which convert ac voltages to dc as needed for powering electronic equipment. 7. A number of other practical and important applications of diodes.
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(c)
(d)
(e) Figure 4.3 5(6#[)5(3:3)*#53*563(=#5&6#!"'6(#/&;):2*1=#5*6#@C63;&0)"(#53*563(#/%)"# v-# ≥# S=#5)6#@C63;&0)"( 53*563(#/%)"#v-#≤#S=#5"6#K6('6(#/&;):2*1=
4.1 The Ideal Diode 169
EXERCISES 4.1# L2*#(%)#53*563(#3"#L3<=#P=OB&D8#+H)(5%#(%)#(*&"+:)*#5%&*&5()*3+(35#v.#;)*+6+#v-= Ans. Y))#L3<=#@P=,=
Figure E4.1
4.2# L2*#(%)#53*563(#3"#L3<=#P=OB&D8#+H)(5%#(%)#/&;):2*1#2:#v+= Ans. v+#\#v-#]#v. 8#*)+60(3"<#3"#(%)#/&;):2*1#3"#L3<=#@P=.
Figure E4.2
4.3# !"#(%)#53*563(#2:#L3<=#P=OB&D8#0)(#v-#%&;)#')&H#;&06)#2:#,S#T#&"-#,#=#,#HΩ=#L3"-#(%)#')&H#;&06)#2:#!+ &"-#(%)#-5#521'2")"(#2:#v.= Ans. ,S#1E7#O=,^#T
Example 4.1 L3<6*)#P=PB&D#+%2/+#5*563(#:2*#5%&*<3"<#,.?T#9&(()*4=#!:#v5#3+#+3"6+23-#/3(%#.P?T#')&H#&1'03? (6-)8#:3"-#(%)#:*&5(32"#2:#)&5%#5450)#-6*3"<#/%35%#(%)#-32-)#52"-65(+=#E0+28#:3"-#(%)#')&H#;&06)#2: (%)#-32-)#56**)"(#&"-#(%)#1&A3161#*);)*+)?93&+#;20(&<)#(%&(#&'')&*+#&5*2++#(%)#-32-)=
170 Chapter 4 Diodes Example 4.1 continued
(b)
(a) Figure 4.4 $3*563(#&"-#/&;):2*1+#:2*#@A&1'0)#P=,=
Solution F%)# -32-)# 52"-65(+# /%)"# v5# )A5))-+# ,.# T8# &+# +%2/"# 3"# L3<=# P=PB9D=# F%)# 52"-65(32"# &"<0)# 3+# .θ8 /%)*)#θ#3+#<3;)"#94 .P#52+ θ = ,.
F%6+#θ#=#`S°#&"-#(%)#52"-65(32"#&"<0)#3+#,.S°8#2*#2")?(%3*-#2:#ᕊ)= F%)#')&H#;&06)#2:#(%)#-32-)#56**)"(#3+#<3;)"#94 ! ,.? " S=,.#E - * " .P ????????????????? ,SS
F%)#1&A3161#*);)*+)#;20(&<)#&5*2++#(%)#-32-)#2556*+#/%)"#v5 3+#&(#3(+#")<&(3;)#')&H#&"-#3+#)C6&0#(2 .P#+#,.#=#O`#T=
4.1.3 Another Application: Diode Logic Gates R32-)+#(2<)(%)*#/3(%#*)+3+(2*+#5&"#9)#6+)-#(2#31'0)1)"(#-3<3(&0#02<35#:6"5(32"+=#L3<6*)#P=Z +%2/+#(/2#-32-)#02<35#<&()+=#F2#+))#%2/#(%)+)#53*563(+#:6"5(32"8#52"+3-)*#'2+3(3;)?02<35 +4+()1#3"#/%35%#;20(&<)#;&06)+#502+)#(2#S#T#52**)+'2"-#(2#02<35#S#B2*#02/D#&"-#;20(&<)#;&06)+ 502+)#(2#+Z#T#52**)+'2"-#(2#02<35#,#B2*#%3<%D=#F%)#53*563(#3"#L3<=#P=ZB&D#%&+#(%*))#3"'6(+8#v6 8 v78#&"-#v8=#!(#3+#)&+4#(2#+))#(%&(#-32-)+#52"")5()-#(2#+Z?T#3"'6(+#/300#52"-65(8#(%6+#50&1'3"< (%)# 26('6(# v9# (2# ;&06)# )C6&0# (2# +Z# T=# F%3+# '2+3(3;)# ;20(&<)# &(# (%)# 26('6(# /300# H))'# (%) -32-)+# /%2+)# 3"'6(+#&*)#02/#B&*26"-#S#TD#56(# 2::=#F%6+# 4:30&;4#;40(!<<0=30:!>:0!%0&$30&' 1&'30&%04:30!$#;4?0)'30:!>:=#F%)#53*563(#(%)*):2*)#31'0)1)"(+#(%)#4-7'*%89%.+1*,'-18#/%35% 3"#_220)&"#"2(&(32"#3+#)A'*)++)-#&+
9 = 6+7+8 Y3130&*048#(%)#*)&-)*#3+#)"526*&<)-#(2#+%2/#(%&(#6+3"<#(%)#+&1)#02<35#+4+()1#1)"(32")&92;)8#(%)#53*563(#2:#L3<=#P=ZB9D#31'0)1)"(+#(%)#4-7'*%:;<%.+1*,'-18 9 = 6⋅7⋅8
4.1 The Ideal Diode 171
(a)
(b)
Figure 4.5 R32-)#02<35#<&()+Q#5(6#K[#<&()7#5&6#EXR#<&()#B3"#'2+3(3;)?02<35#+4+()1D=
Example 4.2 E++613"<#(%)#-32-)+#(2#9)#3-)&08#:3"-#(%)#;&06)+#2:#-#&"-#@#3"#(%)#53*563(+#2:#L3<=#P=`=
D
D
(a)
D
D
(b)
Figure 4.6 $3*563(+#:2*#@A&1'0)#P=.=
Solution !"#(%)+)#53*563(+#3(#13<%(#"2(#9)#29;326+#&(#:3*+(#+3<%(#/%)(%)*#"2")8#2")8#2*#92(%#-32-)+#&*)#52"-65(3"<= !"#+65%#&+)8#(301)A30)0#<);?!=<30)??;1#4!&$B0#'&/33*0(!4:04:30)$)
172 Chapter 4 Diodes
Example 4.2 continued
,S ! S - +. = ??????????????? = ,#1E ,S I*3(3"<#"2-)#)C6&(32"#&(#_8 S ! ( ! ,S ) - + , = ??????????????????????? Z
*)+60(+#3"#-#=#,#1E=#F%6+#+,#3+#52"-65(3"<#&+#2*3<3"&004#&++61)-8#&"-#(%)#:3"&0#*)+60(#3+#-#= , 1E#&"-#@#=#S#T= L2*# (%)# 53*563(# 3"# L3<=# P=`B9D8# 3:# /)# &++61)# (%&(# 92(%# -32-)+# &*)# 52"-65(3"<8# (%)" @7 = S#&"-#@#=#S=#F%)#56**)"(#3"#+.#3+#29(&3")-#:*21 ,S ! S - +. = ??????????????? = .#1E Z F%)#"2-)#)C6&(32"#&(#_#3+ S ! ( ! ,S ) - + . = ??????????????????????? ,S /%35%#43)0-+#-0=#−,#1E=#Y3"5)#(%3+#3+#"2(#'2++390)8#26*#2*3<3"&0#&++61'(32"#3+#$&4#52**)5(=#I) +(&*(#&<&3"8#&++613"<#(%&(#+,#3+#2::#&"-#+.#3+#2"=#F%)#56**)"(#-+.#3+#<3;)"#94 ,S ! ( ! ,S ) - +. = ?????????????????????????? = ,=OO#1E ,Z &"-#(%)#;20(&<)#&(#"2-)#_#3+ @ 7 = ],S + ,S × ,=OO = +O=O#T
F%6+#+,#3+#*);)*+)#93&+)-#&+#&++61)-8#&"-#(%)#:3"&0#*)+60(#3+#-0=#S#&"-#@#=#O=O#T=
EXERCISES 4.4# L3"-#(%)#;&06)+#2:#-#&"-#@#3"#(%)#53*563(+#+%2/"#3"#L3<=#@P=P=
(a) Figure E4.4
(b)
(c)
(d)
4.2 Terminal Characteristics of Junction Diodes 173
(f)
(e) Figure E4.4 B$2"(3"6)-D
Ans. B&D#.#1E8#S#T7#B9D#S#1E8#Z#T7#B5D#S#1E8#Z#T7#B-D#.#1E8#S#T7#B)D#O#1E8#+O#T7#B:D#P#1E8#+,#T 4.5# L3<6*)#@P=Z#+%2/+#5*563(#:2*#&"#&5#;20(1)()*=#!(#6(303M)+#3"5230#1)()*#(%&(#<3;)+#:600?+5&0)#*)&-? 3"<#/%)"#(%)#)D3')>3#56**)"(#:02/3"<#(%*26<%#3(#3+#,#1E=#F%)#12;3"5230#1)()*#%&+#ZS?Ω#*)+3+(&"5)=
Moving-coil meter Figure E4.5
L3"-# (%)# ;&06)# 2:# ,# (%&(# *)+60(+# 3"# (%)# 1)()*# 3"-35&(3"<# :600?+5&0)# *)&-3"<# /%)"# (%)# 3"'6(# +3")?/&;) ;20(&<)#vI#3+#.S#T#')&H?(2?')&H=#BE!$4F#F%)#&;)*&<)#;&06)#2:#%&0:?+3")#/&;)+#3+#@# aπ=D# Ans. #O=,OO#HΩ
4.2 Terminal Characteristics of Junction Diodes F%)#12+(#52112"#31'0)1)"(&(32"#2:#(%)#-32-)#6(303M)+##$#J6"5(32"=#I)#%&;)#+(6-3)-#(%) '%4+35+#2:#(%)##$#J6"5(32"#&"-#-)*3;)-#3(+#!]v#5%&*&5()*3+(35#3"#$%&'()*#O=#F%&(#(%)##$#J6"5? (32"#3+#6+)-#(2#31'0)1)"(#(%)#-32-)#:6"5(32"#+%260-#521)#&+#"2#+6*'*3+)Q#(%)##$#J6"5(32"#5&" 52"-65(# +69+(&"(3&0# 56**)"(# 3"# (%)# :2*/&*-# -3*)5(32"# &"-# &012+(# "2# 56**)"(# 3"# (%)# *);)*+) -3*)5(32"=#!"#(%3+#+)5(32"#/)#+(6-4#(%)#!]v#5%&*&5()*3+(35#2:#(%)##$#J6"5(32"#-32-)#3"#-)(&30#3" 2*-)*#(2#'*)'&*)#26*+)0;)+#:2*#-32-)#53*563(#&''035&(32"+= L3<6*)#P=N#+%2/+#(%)#!]v#5%&*&5()*3+(35#2:#+30352"#J6"5(32"#-32-)=#F%)#+&1)#5%&*&5()*3+? (35#3+#+%2/"#3"#L3<=#P=^#/3(%#+21)#+5&0)+#)A'&"-)-#&"-#2(%)*+#521'*)++)-#(2#*);)&0#-)(&30+= X2()#(%&(#(%)#+5&0)#5%&"<)+#%&;)#*)+60()-#3"#(%)#&''&*)"(#-3+52"(3"63(4#&(#(%)#2*3<3"=
174 Chapter 4 Diodes
Figure 4.7 F%)#!]v##5%&*&5()*3+(35#2:#+30352"#J6"5(32"#-32-)=
Figure 4.8 F%)# -32-)# !]v# # *)0&(32"+%3'# /3(%# +21)# +5&0)+# )A'&"-)-# &"-# 2(%)*+# 521'*)++)-# 3"# 2*-)*# (2 *);)&0#-)(&30+=
E+#3"-35&()-8#(%)#5%&*&5()*3+(35#56*;)#52"+3+(+#2:#(%*))#-3+(3"5(#*)<32"+Q 1. F%)#:2*/&*-?93&+#*)<32"8#-)()*13")-#94#v#b#S 2. F%)#*);)*+)?93&+#*)<32"8#-)()*13")-#94#v#c#S 3. F%)#9*)&H-2/"#*)<32"8#-)()*13")-#94#v#c#]@GH F%)+)#(%*))#*)<32"+#2:#2')*&(32"#&*)#-)+5*39)-#3"#(%)#:2002/3"<#+)5(32"+=
4.2 Terminal Characteristics of Junction Diodes 175
4.2.1 The Forward-Bias Region F%)# :2*/&*-?93&+W2*# +31'04# :2*/&*-W*)<32"# 2:# 2')*&(32"# 3+# )"()*)-# /%)"# (%)# ()*13"&0 ;20(&<)#v#3+#'2+3(3;)=#!"#(%)#:2*/&*-#*)<32"#(%)#!]v#*)0&(32"+%3'#3+#502+)04#&''*2A31&()-#94# v⁄@ BP=,D ! = -5 ( 3 I ! , ) !"#(%3+#)C6&(32",#-5#3+#4"+(&"(#:2*#<3;)"#-32-)#&(#<3;)"#()1')*&(6*)=#E#:2*160:2*#-5#3" ()*1+#2:#(%)#-32-)d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v=#L2*#e+1&00?+3<"&0f#-32-)+8#/%35%#&*)#+1&00?+3M)#-32-)+#3"()"-)-#:2*#02/?'2/)*#&''035&? (32"+8#-5#3+#2"#(%)#2*-)*#2:#,S],Z#E=#F%)#;&06)#2:#-5#3+8#%2/);)*8#)*4#+(*2"<#:6"5(32"#2:#()1? ')*&(6*)=#E+#*60)#2:#(%6198#-5#-2690)+#3"#;&06)#:2*#);)*4#Z°$#*3+)#3"#()1')*&(6*)= F%)#;20(&<)#@I#3"#@C=#BP=,D#3+#4"+(&"(#5&00)-#(%)#,2"!=(4%#-4,(7"#&"-#3+#<3;)"#94
AI @I = ?????? J
BP=.D
/%)*) A0=#_20(M1&""d+#52"+(&"(#=#^=`.#× ,S]Z#)Tag#=#,=O^#× ,S].O#J260)+aH)0;3" I0=#(%)#&9+206()#()1')*&(6*)#3"#H)0;3"+#=#.NO#+#()1')*&(6*)#3"#°$ J#=#(%)#1&<"3(6-)#2:#)0)5(*2"35#5%&*<)#=#,=`S#×#,S],U#5260219# Y69+(3(6(3"<#A#\#^=`.#× ,S]Z#)Tag#3"(2#@C=#BP=.D#<3;)+
@I = S=S^`.I8 1@
BP=.&D
F%6+8#&(#*221#()1')*&(6*)#B.S°$D#(%)#;&06)#2:#@I#3+#.Z=O#1T=#!"#*&'3-#&''*2A31&()#53*563( &"&04+3+#/)#+%&00#6+)#@I#!#.Z#1T#&(#*221#()1')*&(6*)=. L2*#&''*)53&90)#56**)"(#!#3"#(%)#:2*/&*-#-3*)5(32"8#+')53:35&004#:2*#!#%#-5 8#@C=#BP=,D#5&"#9) &''*2A31&()-#94#(%)#)A'2")"(3&0#*)0&(32"+%3' !0! -5 3
vK @
I
BP=OD
F%3+#*)0&(32"+%3'#5&"#9)#)A'*)++)-#&0()*"&(3;)04#3"#(%)#02<&*3(%135#:2*1
! -5
v = @I 0" ????
BP=PD
/%)*)#0"#-)"2()+#(%)#"&(6*&0#B9&+)#3D#02<&*3(%1= ,
@C6&(32"#BP=,D8#(%)#-32-)#)C6&(32"8#3+#+21)(31)+#/*3(()"#(2#3"506-)#4"+(&"(#$#3"#(%)#)A'2")"(3&08 va$A4
#! \ -5 B3
],D
/3(%#$#%&;3"<#&06)#9)(/))"#,#&"-#.8#-)')"-3"<#2"#(%)#1&()*3&0#&"-#(%)#'%4+35&0#+(*65(6*)#2:#(%)#-32-)= R32-)+#6+3"<#(%)#+(&"-&*-#3"()<*&()-?53*563(#:&9*35&(32"#'*25)++#)A%393(#$#\#,#/%)"#2')*&()-#6"-)*#"2*? 1&0#52"-3(32"+=#L2*#+31'0353(48#/)#+%&00#6+)#$#\#,#(%*26<%26(#(%3+#922H8#6"0)++#2(%)*/3+)#+')53:3)-= . E#+03<%(04#%3<%)*#&193)"(#()1')*&(6*)#B.Z°$#2*#+2D#3+#6+6&004#&++61)-#:2*#)0)5(*2"35#)C63'1)"(#2')*? &(3"<#3"+3-)#&93")(=#E(#(%3+#()1')*&(6*)8#@I##!#.Z=^#1T=#X);)*(%)0)++8#:2*#(%)#+&H)#2:#+31'0353(4#&"(2#'*212()#*&'3-#53*563(#&"&04+3+8#/)#+%&00#6+)#(%)#12*)#&*3(%1)(35&004#52";)"3)"(#;&06)#2:#@I#!#.Z#1T (%*26<%26(#(%3+#922H=
176 Chapter 4 Diodes F%)#)A'2")"(3&0#*)0&(32"+%3'#2:#(%)#56**)"(#!#(2#(%)#;20(&<)#v#%20-+#2;)*#1&"4#-)5&-)+#2: 56**)"(#B+'&"#2:#&+#1&"4#&+# +);)"#-)5&-)+W3=)=8#:&5(2*#2:#,SNW5&"#9)#:26"-D=#F%3+#3+ C63()#*)1&*H&90)#'*2')*(4#2:#J6"5(32"#-32-)+8#2")#(%&(#3+#&0+2#:26"-#3"#93'20&*#J6"5(32"#(*&"? +3+(2*+#&"-#(%&(#%&+#9))"#)A'023()-#3"#1&"4#3"()*)+(3"<#&''035&(32"+= V)(# 6+# 52"+3-)*# (%)# :2*/&*-# !"v0 *)0&(32"+%3'# 3"# @C=# BP=OD# &"-# );&06&()# (%)# 56**)"(# -, 52**)+'2"-3"<#(2#-32-)#;20(&<)#@,Q
-, = -5 3
@, ⁄ @I
Y3130&*048#3:#(%)#;20(&<)#3+#@.8#(%)#-32-)#56**)"(#-.#/300#9)
- . = -5 3
@. ⁄ @I
F%)+)#(/2#)C6&(32"+#5&"#9)#52193")-#(2#'*2-65) (@ ! @ ) ⁄ @ ????. = 3 . , I -,
/%35%#5&"#9)#*)/*3(()"#&+
@ . ! @ , = @ I 0" ????. -, 2*8#3"#()*1+#2:#9&+)?,S#02<&*3(%1+8
@ . ! @ , = .=O@I 02< ????. -,
BP=ZD
F%3+#)C6&(32"#+31'04#+(&()+#(%&(#:2*#-)5&-)#B:&5(2*#2:#,SD#5%&"<)#3"#56**)"(8#(%)#-32-)#;20(? &<)#-*2'#5%&"<)+#94#.=O@I 8#/%35%#3+#&''*2A31&()04#`S#1T=#F%3+#&0+2#+6<<)+(+#(%&(#(%)#-32-) !"v# *)0&(32"+%3'# 3+# 12+(# 52";)"3)"(04# '02(()-# 2"# +)1302<# '&')*=# h+3"<# (%)# ;)*(35&08# 03")&* &A3+#:2*#v#&"-#(%)#%2*3M2"(&08#02<#&A3+#:2*#!8#2")#29(&3"+#+(*&3<%(#03")#/3(%#+02')#2:#`S 1T ')*#-)5&-)#2:#56**)"(= E#<0&"5)#&(#(%)#!"v#5%&*&5()*3+(35#3"#(%)#:2*/&*-#*)<32"#BL3<=#P=^D#*);)&0+#(%&(#(%)#56**)"( 3+#")<03<3904#+1&00#:2*#v#+1&00)*#(%&"#&926(#S=Z#T=#F%3+#;&06)#3+#6+6&004#*):)**)-#(2#&+#(%)#*+,0 '1%#-4,(7"=#!(#+%260-#9)#)1'%&+3M)-8#%2/);)*8#(%&(#(%3+#&''&*)"(#(%*)+%20-#3"#(%)#5%&*&5()*3+? (35#3+#+31'04#4"+)C6)"5)#2:#(%)#)A'2")"(3&0#*)0&(32"+%3'=#E"2(%)*#52"+)C6)"5)#2:#(%3+#*)0&? (32"+%3'#3+#(%)#*&'3-#3"5*)&+)#2:#!=#F%6+8#:2*#e:6004#52"-65(3"
Example 4.3 E#+30352"#-32-)#+&3-#(2#9)#,?1E#-);35)#-3+'0&4+#:2*/&*-#;20(&<)#2:#S=N#T#&(#8**)"(#2:#,#1E= @;&06&()#(%)#J6"5(32"#+5&03"<#52"+(&"(#-5=#I%&(#+5&03"<#52"+(&"(+#/260-#&''04#:2*#,?E#-32-)#2:#(%) +&1)#1&"6:&5(6*)#(%&(#52"-65(+#,#E#&(#S=N#Ti
4.2 Terminal Characteristics of Junction Diodes 177
Solution Y3"5)# ! = -5 3
v ⁄ @I
(%)" - 5 = !3
!v ⁄ @I
L2*#(%)#,?1E#-32-)Q -5#=#,S−O3−NSSa.Z#=#`=U#×#,S−,`#E F%)#-32-)#52"-65(3"<#,#E#&(#S=N#T#52**)+'2"-+#(2#2")?(%26+&"-#,?1E#-32-)+#3"#'&*&00)0#/3(%#(2(&0 J6"5(32"#&*),SSS#(31)+#<*)&()*=#F%6+#-5#3+#&0+2#,SSS#(31)+#<*)&()*8# -5#=##`=U#×#,S−,O#E Y3"5)#92(%#-5#&"-#@I#&*)#:6"5(32"+#2:#()1')*&(6*)8#(%)#:2*/&*-#!"v#5%&*&5()*3+(35#;&*3)+#/3(%#()1? ')*&(6*)8#&+#3006+(*&()-#3"#L3<=#P=U=#E(#<3;)"#52"+(&"(#-32-)#56**)"(8#(%)#;20(&<)#-*2'#&5*2++#(%)#-32-) -)5*)&+)+#94#&''*2A31&()04#.#1T#:2*#);)*4#,°$#3"5*)&+)#3"#()1')*&(6*)=#F%)#5%&"<)#3"#-32-)#;20(? &<)#/3(%#()1')*&(6*)#%&+#9))"#)A'023()-#3"#(%)#-)+3<"#2:#)0)5(*2"35#(%)*121)()*+=
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EXERCISES 4.6# L3"-#(%)#5%&"<)#3"#-32-)#;20(&<)#3:#(%)#56**)"(#5%&"<)+#:*21#S=,#1E#(2#,S#1E= Ans. ,.S#1T 4.7# E#+30352"#J6"5(32"#-32-)#%&+#v#= #S=N#T#&(#!0=#,#1E=#L3"-#(%)#;20(&<)#-*2'#&(#!#=#S=,#1E#&"-# ! =#,S#1E= Ans. #S=`P#T7#S=N`#T 4.8# h+3"<#(%)#:&5(#(%&(#+30352"#-32-)#%&+#-5#=#,S−,P#E#&(#.Z°$#&"-#(%&(#-5#3"5*)&+)+#94#,Zj#')*#°$#*3+)#3" ()1')*&(6*)8#:3"-#(%)#;&06)#2:#-5#&(#,.Z°$=## Ans. ,=,N#×#,S−^#E
178 Chapter 4 Diodes
4.2.2 The Reverse-Bias Region F%)#*);)*+)?93&+#*)<32"#2:#2')*&(32"#3+#)"()*)-#/%)"#(%)#-32-)#;20(&<)#v#3+#1&-)#")<&(3;)=#@C6&? (32"#BP=,D#'*)-35(+#(%&(#3:#v#3+#")<&(3;)#&"-#:)/#(31)+#0&*<)*#(%&"#@I#B.Z#1TD#3"#1&<"3(6-)8#(%) )A'2")"(3&0#()*1#9)521)+#")<03<3904#+1&00#521'&*)-#(2#6"3(48#&"-#(%)#-32-)#56**)"(#9)521)+ !#! ]-5 F%&(#3+8#(%)#56**)"(#3"#(%)#*);)*+)#-3*)5(32"#3+#52"+(&"(#&"-#)C6&0#(2#-5=#F%3+#52"+(&"54#3+#(%) *)&+2"#9)%3"-#(%)#()*1#?)4;')4!&$0/;''3$4= [)&0#-32-)+#)A%393(#*);)*+)#56**)"(+#(%&(8#(%26<%#C63()#+1&008#&*)#165%#0&*<)*#(%&"#-5=#L2* 3"+(&"5)8#+1&00?+3<"&0#-32-)#/%2+)#-5#3+#2"#(%)#2*-)*#2:#,S−,P#E#(2#,S−,Z#E#5260-#+%2/#& *);)*+)#56**)"(#2"#(%)#2*-)*#2:#,#"E=#F%)#*);)*+)#56**)"(#&0+2#3"5*)&+)+#+21)/%&(#/3(%#(%) 3"5*)&+)#3"#1&<"3(6-)#2:#(%)#*);)*+)#;20(&<)=#X2()#(%&(#9)5&6+)#2:#(%)#;)*4#+1&00#1&<"3(6-) 2:#(%)#56**)"(8#(%)+)#-)(&30+#&*)#"2(#50)&*04#);3-)"(#2"#(%)#-32-)#!]v#5%&*&5()*3+(35#2:#L3<=#P=^=# E#0&*<)#'&*(#2:#(%)#*);)*+)#56**)"(#3+#-6)#(2#0)&H&<)#)::)5(+=#F%)+)#0)&H&<)#56**)"(+#&*) '*2'2*(32"&0#(2#(%)#J6"5(32"#&*)&8#J6+(#&+#-5#3+=#F%)3*#-)')"-)"5)#2"#()1')*&(6*)8#%2/);)*8#3+ -3::)*)"(#:*21#(%&(#2:#-5=#F%6+8#/%)*)&+#-5#-2690)+#:2*#);)*4#Z°$#*3+)#3"#()1')*&(6*)8#(%)#52**)? +'2"-3"<#*60)#2:#(%619#:2*#(%)#()1')*&(6*)#-)')"-)"5)#2:#(%)#*);)*+)#56**)"(#3+#(%&(#3(#-26? 90)+#:2*#);)*4#,S°$#*3+)#3"#()1')*&(6*)=
EXERCISE 4.9# F%)#-32-)#3"#(%)#53*563(#2:#L3<=#@P=U#3+#&*<)#%3<%?56**)"(#-);35)#/%2+)#*);)*+)#0)&H&<)#3+#*)&+2"&904 3"-)')"-)"(#2:#;20(&<)=#!:#@#=#,#T#&(#.0°$8#:3"-#(%)#;&06)#2:#@#&(#PS°$#&"-#&(#S°$=
Figure E4.9
Ans. P#T7#S=.Z#T
4.2.3 The Breakdown Region F%)#(%3*-#-3+(3"5(#*)<32"#2:#-32-)#2')*&(32"#3+#(%)#9*)&H-2/"#*)<32"8#/%35%#5&"#9)#)&+304 3-)"(3:3)-#2"#(%)#-32-)#!]v#5%&*&5()*3+(35#3"#L3<=#P=^=#F%)#9*)&H-2/"#*)<32"#3+#)"()*)-#/%)"#(%) 1&<"3(6-)#2:#(%)#*);)*+)#;20(&<)#)A5))-+#(%*)+%20-#;&06)#(%&(#3+#+')53:35#(2#(%)#'&*(3560&*#-32-)8 5&00)-#(%)#&!"(>)-/1%#-4,(7"=#F%3+#3+#(%)#;20(&<)#&(#(%)#eH"))f#2:#(%)#!]v#56*;)#3"#L3<=#P=^#&"-#3+ -)"2()-#@GH8#/%)*)#(%)#+69+5*3'(#G#+(&"-+#:2*#M)")*#B+))#Y)5(32"#O=Z=OD#&"-#H#-)"2()+#H"))=
4.3 Modeling the Diode Forward Characteristic 179
E+#5&"#9)#+))"#:*21#L3<=#P=^8#3"#(%)#9*)&H-2/"#*)<32"#(%)#*);)*+)#56**)"(#3"5*)&+)+#*&'? 3-048#/3(%#(%)#&++253&()-#3"5*)&+)#3"#;20(&<)#-*2'#9)3"<#;)*4#+1&00=#R32-)#9*)&H-2/"#3+#"2*? 1&004# "2(# -)+(*65(3;)8# '*2;3-)-# (%)# '2/)*# -3++3'&()-# 3"# (%)# -32-)# 3+# 0313()-# 94# )A()*"&0 53*563(*4#(2#e+&:)f#0);)0=#F%3+#+&:)#;&06)#3+#"2*1&004#+')53:3)-#2"#(%)#-);35)#-&(+%))(+=#!( (%)*):2*)#3+#")5)++&*4#(2#0313(#(%)#*);)*+)#56**)"(#3"#(%)#9*)&H-2/"#*)<32"#(2#&06)#52"+3+? ()"(#/3(%#(%)#')*13++390)#'2/)*#-3++3'&(32"= F%)#:&5(#(%&(#(%)#-32-)#!]v#5%&*&5()*3+(35#3"#9*)&H-2/"#3+#&012+(#)*(35&0#03")#)"&90)+#3( (2#9)#6+)-#3"#;20(&<)#*)<60&(32"=#F%3+#+69J)5(#/300#9)#+(6-3)-#3"#Y)5(32"#P=Z=
4.3 Modeling the Diode Forward Characteristic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
4.3.1 The Exponential Model F%)#12+(#&556*&()#-)+5*3'(32"#2:#(%)#-32-)#2')*&(32"#3"#(%)#:2*/&*-#*)<32"#3+#'*2;3-)-#94 (%)# )A'2")"(3&0# 12-)0=# h":2*(6"&()048# %2/);)*8# 3(+# +);)*)04# "2"03")&*# "&(6*)# 1&H)+# (%3+ 12-)0#(%)#12+(#-3::3560(#(2#6+)=#F2#3006+(*&()8#0)(d+#&"&04M)#(%)#53*563(#3"#L3<=#P=,S#6+3"<#(%) )A'2")"(3&0#-32-)#12-)0= E++613"<#(%&(#@++#3+#<*)&()*#(%&"#S=Z#T#2*#+28#(%)#-32-)#56**)"(#/300#9)#165%#<*)&()*#(%&" -5 8#&"-#/)#5&"#*)'*)+)"(#(%)#-32-)#!]v#5%&*&5()*3+(35#94#(%)#)A'2")"(3&0#*)0&(32"+%3'8#*)+60(3"<#3"
-+ = -5 3
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180 Chapter 4 Diodes
4.3.2 Graphical Analysis Using the Exponential Model k*&'%35&0#&"&04+3+#3+#')*:2*1)-#94#'02((3"<#(%)#*)0&(32"+%3'+#2:#@C+=#BP=`D#&"-#BP=ND#2"#(%) !]v#'0&")=#F%)#+206(32"#5&"#(%)"#9)#29(&3")-#&+#(%)#522*-3"&()+#2:#(%)#'23"(#2:#3"()*+)5(32"#2: (%)#(/2#<*&'%+=#E#+H)(5%#2:#(%)#<*&'%35&0#52"+(*65(32"#3+#+%2/"#3"#L3<=#P=,,=#F%)#56*;)#*)'? *)+)"(+#(%)#)A'2")"(3&0#-32-)#)C6&(32"#B@C=#P=`D8#&"-#(%)#+(*&3<%(#03")#*)'*)+)"(+#@C=#BP=ND= Y65%#+(*&3<%(#03")#3+#H"2/"#&+#(%)#4-()%4'1"8#"&1)#(%&(#/300#9)521)#12*)#1)&"3"<:60 3"#0&()*#5%&'()*+=#F%)#02&-#03")#3"()*+)5(+#(%)#-32-)#56*;)#&(#'23"(#L8#/%35%#*)'*)+)"(+#(%) -3"!(,'17%3-'1,#2:#(%)#53*563(=#!(+#522*-3"&()+#<3;)#(%)#;&06)+#2:#-+#&"-#@+= k*&'%35&0# &"&04+3+# &3-+# 3"# (%)# ;3+6&03M&(32"# 2:# 53*563(# 2')*&(32"=# >2/);)*8# (%)# )::2*( 3";20;)-#3"#')*:2*13"<#+65%#&"#&"&04+3+8#'&*(3560&*04#:2*#521'0)A#53*563(+8#3+#(22#<*)&(#(2#9)#J6+(3? :3)-#3"#'*&5(35)=
Figure 4.11 k*&'%35&0#&"&04+3+#2:#(%)#53*563(#3"#L3<=#P=,S#6+3"<#(%)#)A'2")"(3&0#-32-)#12-)0=
4.3.3 Iterative Analysis Using the Exponential Model @C6&(32"+#BP=`D#&"-#BP=ND#5&"#9)#+20;)-#6+3"<#+31'0)#3()*&(3;)#'*25)-6*)8#&+#3006+(*&()-#3" (%)#:2002/3"<#)A&1'0)=
Example 4.4 R)()*13")#(%)#56**)"(#-+#&"-#(%)#-32-)#;20(&<)#@+#:2*#(%)#53*563(#3"#L3<=#P=,S#/3(%#@++#=#Z#T#&"-# ,#=#,#HΩ=#E++61)#(%&(#(%)#-32-)#%&+#8**)"(#2:#,#1E#&(#20(&<)#2:#S=N#T= Solution F2#9)<3"#(%)#3()*&(32"8#/)#&++61)#(%&(#@+#=#S=N#T#&"-#6+)#@C=#BP=ND#(2#-)()*13")#(%)#56**)"(8 @++ ! @+ ? -+ = ????????????????????? , Z ! S=N = ???????????????? = P=O#1E ,
4.3 Modeling the Diode Forward Characteristic 181
I)#(%)"#6+)#(%)#-32-)#)C6&(32"#(2#29(&3"# )(()*#)+(31&()#:2*#@+=#F%3+#5&"#9)#-2")#94#)1'0243"< @C=#BP=ZD8#"&1)048 @ . ! @ , = .=O@I 02< ???.? -,
Y69+3(6(3"<#.=O@I#=#`S#1T8#/)#%&;) @. = @ , + S=S` 02< ???.? -, Y69+(3(6(3"<#@,#=#S=N#T8#-,#=#,#1E8#&"-#-.#=#P=O#1E#*)+60(+#3"#@.#=#S=NO^#T=#F%6+#(%)#*)+60(+#2:#(%)#:3*+(#3()*? &(32"#&*)#-+#=#P=O#1E#&"-#@+#=#S=NO^#T=#F%)#+)52"-#3()*&(32"#'*25))-+#3"#+3130&*#1&"")*Q Z ! S=NO^ -+ = ?????????????????????? = P=.`.#1E , P=.`. @. = S=NO^ + S=S`#02< ????????????? P=O = S=NO^#T
F%6+#(%)#+)52"-#3()*&(32"#43)0-+#-+#=#P=.`.#1E#&"-#@+#=#S=NO^#T=#Y3"5)#(%)+)#;&06)+#&*)#;)*4#502+) (2#(%)#;&06)+#29(&3")-#&:()*#(%)#:3*+(#3()*&(32"8#"2#:6*(%)*#3()*&(32"+#&*)#")5)++&*48#&"-#(%)#+206(32"#3+ -+#=#P=.`.#1E#&"-#@+#=#S=NO^#T=
4.3.4 The Need for Rapid Analysis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ȉ'6()*#53*563(?&"&04+3+#'*2<*&1#+65%#&+#Yl!$@ B+))#E'')"-3A#_#&"-#(%)#-3+5D=#F%)#*)+60(+#2:#+65%#&"#&"&04+3+#5&"#(%)"#9)#6+)-#(2#:6*(%)* *):3")#2*#e:3")?(6")f#(%)#-)+3<"= F2#+'))-#6'#(%)#&"&04+3+#'*25)++8#/)#16+(#:3"-#+31'0)*#12-)0#:2*#(%)#-32-)#:2*/&*5%&*&5()*3+(35=
4.3.5 The Constant-Voltage-Drop Model F%)#+31'0)+(#&"-#12+(#/3-)04#6+)-#-32-)#12-)0#3+#(%)#52"+(&"(?;20(&<)?-*2'#12-)0=#F%3+ 12-)0#3+#9&+)-#2"#(%)#29+)*;&(32"#(%&(#:2*/&*-?52"-65(3"<#-32-)#%&+#20(&<)#-*2'#(%&( ;&*3)+#3"#*)0&(3;)04#"&**2/#*&"<)8#+&4#S=`#(2#S=^#T=#F%)#12-)0#&++61)+#(%3+#;20(&<)#(2#9) 52"+(&"(#&(#&06)8#+&48#S=N#T=#F%3+#-);)02'1)"(#3+#3006+(*&()-#3"#L3<=#P=,.=
182 Chapter 4 Diodes
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Figure 4.12 R);)02'1)"(#2:#(%)#-32-)#52"+(&"(?;20(&<)?-*2'#12-)0Q#5(6#(%)#)A'2")"(3&0#5%&*&5()*? +(357# 5&6# &''*2A31&(3"<# (%)# )A'2")"(3&0# 5%&*&5()*3+(35# 94# 52"+(&"(# ;20(&<)8# 6+6&004# &926(# S=N# T37 5*6 (%)#*)+60(3"<#12-)0#2:#(%)#:2/&*-]52"-65(3"<#-32-)+=
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@+ = S=N#T &"-
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4.3 Modeling the Diode Forward Characteristic
4.3.6 The Ideal-Diode Model !"#&''035&(32"+#(%&(#3";20;)#;20(&<)+#165%#<*)&()*#(%&"#(%)#-32-)#;20(&<)#-*2'#BS=`#T]S=^#TD8 /)#1&4#")<0)5(#(%)#-32-)#;20(&<)#-*2'#&0(2<)(%)*#/%30)#5&0560&(3"<#(%)#-32-)#56**)"(=#F%)#*)+60( 3+# (%)# 3-)&0?-32-)# 12-)08# /%35%# /)# +(6-3)-# 3"# Y)5(32"# P=,=# L2*# (%)# 53*563(# 3"# @A&1'0)+# P=P B3=)=8 L3<=#P=,S#/3(%#@++#=#Z#T#&"-#,#=#,#HΩD8#6(303M&(32"#2:#(%)#3-)&0?-32-)#12-)0#0)&-+#(2#
@ + = S#T Z!S - + = ???????????? = Z#1E , /%35%#:2*#)*4#C635H#&"&04+3+#/260-#"2(#9)#9&-#&+#<*2++#)+(31&()=#>2/);)*8#/3(%#&012+( "2#&--3(32"&0#/2*H8#(%)#S=N?T?-*2'#12-)0#43)0-+#165%#12*)#*)&03+(35#*)+60(+=#I)#"2()8#%2/? );)*8#(%&(#(%)#<*)&()+(#6(303(4#2:#(%)#3-)&0?-32-)#12-)0#3+#3"#-)()*13"3"<#/%35%#-32-)+#&*)#2" &"-#/%35%#&*)#2::#3"# (3-32-)#53*563(8#+65%#&+#(%2+)#52"+3-)*)-#3"#Y)5(32"#P=,=
EXERCISES 4.10#L2*#(%)#53*563(#3"#L3<=#P=,S8#:3"-#-+#&"-#@+#:2*#(%)#5&+)#@++#=#Z#T#&"-#,#=#,S#HΩ=#E++61)#(%&(#(%) -32-)#%&+#20(&<)#2:#S=N#T#&(#,?1E#56**)"(=#h+)#B&D#3()*&(32"#&"-#B9D#(%)#52"+(&"(?;20(&<)?-*2' 12-)0#/3(%#@+#=#S=N#T= Ans. B&D#S=PO#1E8#S=`^#T7#B9D#S=PO#1E8#S=N#T D4.11#R)+3<"#(%)#53*563(#3"#L3<=#@P=,,#(2#'*2;3-)#&"#26('6(#;20(&<)#2:#.=P#T=#E++61)#(%&(#(%)#-32-)+#&;&30&90) %&;)#S=N?T#-*2'#&(#,#1E=
Figure E4.11
Ans. ,#=#,OU#Ω 4.12# [)')&(#@A)*53+)#P=P#6+3"<#(%)#S=N?T?-*2'#12-)0#(2#29(&3"#9)(()*#)+(31&()+#2:#-#&"-#@#(%&"#(%2+)#:26"3"#@A)*53+)#P=P#B6+3"<#(%)#3-)&0?-32-)#12-)0D= Ans. B&D#,=N.#1E8#S=N#T7#B9D#S#1E8#Z#T7#B5D#S#1E8#Z#T7#B-D#,=N.#1E8#S=N#T7#B)D#.=O#1E8#+.=O#T7# B:D#O=O#1E8#+,=N#T
183
184 Chapter 4 Diodes
4.3.7 The Small-Signal Model F%)*)#&*)#&''035&(32"+#3"#/%35%#-32-)#3+#93&+)-#(2#2')*&()#&(#'23"(#2"#(%)#:2*/&*-#!]v 5%&*&5()*3+(35#&"-#+1&00#&5#+3<"&0#3+#+6')*31'2+)-#2"#(%)#-5#C6&"(3(3)+=#L2*#(%3+#+3(6&(32"8 /)# :3*+(# %&;)# (2# -)()*13")# (%)# -5# 2')*&(3"<# '23"(# B@+# &"-# -+D# 2:# (%)# -32-)# 6+3"<# 2")# 2: (%) 12-)0+# -3+56++)-# &92;)=# m2+(# :*)C6)"(048# (%)# S=N?T?-*2'# 12-)0# 3+# 6(303M)-=# F%)"8# :2* +1&00?+3<"&0#2')*&(32"#&*26"-#(%)#-5#93&+#'23"(8#(%)#-32-)#3+#12-)0)-#94#*)+3+(&"5)#)C6&0#(2 (%)#3";)*+)#2:#(%)#+02')#2:#(%)#(&"<)"(#(2#(%)#)A'2")"(3&0#!]v#5%&*&5()*3+(35#&(#(%)#93&+#'23"(= F%)# ()5%"3C6)# 2:# 93&+3"<# "2"03")&*# -);35)# &"-# *)+(*35(3"<# +3<"&0# )A56*+32"# (2# +%2*(8 &012+(?03")&*#+)<1)"(#2:#3(+#5%&*&5()*3+(35#&*26"-#(%)#93&+#'23"(#3+#5)"(*&0#(2#-)+3<"3"<#03")&* &1'03:3)*+# 6+3"<# (*&"+3+(2*+8# &+# /300# 9)# +))"# 3"# (%)# ")A(# (/2# 5%&'()*+=# !"# (%3+# +)5(32"8# /) -);)02'#+65%#+1&00?+3<"&0#12-)0#:2*#(%)#J6"5(32"#-32-)#&"-#3006+(*&()#3(+#&''035&(32"=#
Figure 4.13 R);)02'1)"(#2:#(%)#-32-)#+1&00?+3<"&0#12-)0=
4.3 Modeling the Diode Forward Characteristic 185
$2"+3-)*#(%)#52"5)'(6&0#53*563(#3"#L3<=#P=,OB&D#&"-#(%)#52**)+'2"-3"<#<*&'%35&0#*)'*)+)"? (&(32"#3"#L3<=#P=,OB9D=#E#-5#;20(&<)#@+8#*)'*)+)"()-#94# &(()*48#3+#&''03)-#(2#(%)#-32-)8#&"-#& (31)?;&*43"<# +3<"&0# v* B4D8# &++61)-# B&*93(*&*304D# (2# %&;)# (*3&"<60&*# /&;):2*18# 3+ +6')*31'2+)-#2"#(%)#-5#;20(&<)#@+=#!"#(%)#&9+)"5)#2:#(%)#+3<"&0# v* B4D8#(%)#-32-)#;20(&<)#3+ )C6&0#(2#@+8#&"-#52**)+'2"-3"<048#(%)#-32-)#/300#52"-65(#-5#56**)"(#-+#<3;)"#94
-+ = -5 3
@+ ⁄ @I
BP=^D
I%)"#(%)#+3<"&0#v* B4D#3+#&''03)-8#(%)#(2(&0#3"+(&"(&")26+#-32-)#;20(&<)#v+ B4D#/300#9)#<3;)"#94 v + ( 4 ) = @+ + v * ( 4 ) $2**)+'2"-3"<048#(%)#(2(&0#3"+(&"(&")26+#-32-)#56**)"(#!+ B4D#/300#9) v+ ⁄ @I
!+ ( 4 ) = -5 3
BP=UD
BP=,SD
Y69+(3(6(3"<#:2*#v+#:*21#@C=#BP=UD#<3;)+
!+ ( 4 ) = -5 3
( @+ + v* ) ⁄ @I
BP=,,D
/%35%#5&"#9)#*)/*3(()"
!+ ( 4 ) = -5 3
@+ ⁄ @I
3
v* ⁄ @I
h+3"<#@C=#BP=^D#/)#29(&3"
!+ ( 4 ) = -+ 3
v* ⁄ @I
BP=,.D
X2/#3:#(%)#&1'03(6-)#2:#(%)#+3<"&0#v* B4D#3+#H)'(#+6::353)"(04#+1&00#+65%#(%&( v
?????* (, @I
BP=,OD
(%)"#/)#1&4#)A'&"-#(%)#)A'2")"(3&0#2:#@C=#BP=,.D#3"#+)*3)+#&"-#(*6"5&()#(%)#+)*3)+#&:()*#(%) :3*+(#(/2#()*1+#(2#29(&3"#(%)#&''*2A31&()#)A'*)++32" v
! + ( 4 )# ! #- + , + ?????* @I
BP=,PD
F%3+#3+#(%)#$=(440$'71(4%(33!-?'=(,'-1=#!(#3+#;&03-#:2*#+3<"&0+#/%2+)#&1'03(6-)+#&*)#+1&00)* (%&"#&926(#Z#1T#B+))#@C=#P=,O8#&"-#*)5&00#(%&(#@I#=#.Z 1TD=O L*21#@C=#BP=,PD#/)#%&;)
-+ ! + ( 4 ) = - + + ????? v @I *
BP=,ZD
F%6+8#+6')*31'2+)-#2"#(%)#-5#56**)"(#-+8#/)#%&;)#+3<"&0#56**)"(#521'2")"(#-3*)5(04#'*2? '2*(32"&0#(2#(%)#+3<"&0#;20(&<)#v*=#F%&(#3+8 /%)*)
!+ = -+ + !*
BP=,`D
-+ ! * = ????? v @I *
BP=,ND
L2*#v*#=#Z#1T8# v * ⁄ @ I = S=.=#F%6+#(%)#")A(#()*1#3"#(%)#+)*3)+#)A'&"+32"#2:#(%)#)A'2")"(3&0#/300#9)# ,??.? #× S=.. = S=S.8#:&5(2*#2:#,S#02/)*#(%&"#(%)#03")&*#()*1#/)#H)'(=
O
186 Chapter 4 Diodes F%)#C6&"(3(4#*)0&(3"<#(%)#+3<"&0#56**)"(#!*#(2#(%)#+3<"&0#;20(&<)#v*#%&+#(%)#-31)"+32"+#2:#52"? -65(&"5)8#1%2+#B )8#&"-#3+#5&00)-#(%)#)'-)"%$=(440$'71(4%*-1)+*,(1*"=#F%)#3";)*+)#2:#(%3+ '&*&1)()*#3+#(%)#)'-)"%$=(440$'71(4%!"$'$,(1*"8#2*#'1*!"="1,(4%!"$'$,(1*"8#'* 8 Ω
@ '* = ?????I -+
BP=,^D
X2()#(%&(#(%)#;&06)#2:#'*#3+#3";)*+)04#'*2'2*(32"&0#(2#(%)#93&+#56**)"(#-+= V)(#6+#*)(6*"#(2#(%)#<*&'%35&0#*)'*)+)"(&(32"#3"#L3<=#P=,OB9D=#!(#3+#)&+4#(2#+))#(%&(#6+3"<#(%) +1&00?+3<"&0#&''*2A31&(32"#3+#)C63;&0)"(#(2#&++613"<#(%&(#4:30?!>$)<0)1#04:30!]v#/;'D30!?013$4N F%)#+02')#2:#(%3+#+)<1)"(8#/%35%#3+#)C6&0#(2#(%)#+02')#2:#(%)#(&"<)"(#(2#(%)#!]v#56*;)#&(#(%) 2')*&(3"<# '23"(# L8# 3+# )C6&0# (2# (%)# +1&00?+3<"&0# 52"-65(&"5)=# F%)# *)&-)*# 3+# )"526*&<)-# (2 '*2;)#(%&(#(%)#+02')#2:#(%)#!]v#56*;)#&(#!#=#-+#3+#)C6&0#(2# - + ⁄ @ I 8 #/%35%#3+# , ⁄ ' * 7#(%&(#3+8#
∂! ' * = ,## ????????+? ∂ v+
! + =- +
BP=,UD
L*21#(%)#'*)5)-3"<#/)#52"506-)#(%&(#+6')*31'2+)-#2"#(%)#C6&"(3(3)+#@+#&"-#-+#(%&(#-):3") (%)#-5#93&+#'23"(8#2*#@+'"$*"1,%3-'1,8#2:#(%)#-32-)#/300#9)#(%)#+1&00?+3<"&0#C6&"(3(3)+#v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
Example 4.5 $2"+3-)*#(%)#53*563(#+%2/"#3"#L3<=#P=,PB&D#:2*#(%)#5&+)#3"#/%35%#,#=#,S#HΩ=#F%)#'2/)*#+6''04#@ +#%&+#-5 ;&06)#2:#,S#T#2"#/%35%#3+#+6')*31'2+)-#`S?>M#+3"6+23-#2:#,?T#')&H#&1'03(6-)=#BF%3+#e+3<"&0f#521'2? ")"(# 2:# (%)# '2/)*?+6''04# ;20(&<)# 3+# &"# 31')*:)5(32"# 3"# (%)# '2/)*?+6''04# -)+3<"=# !(# 3+# H"2/"# &+# (%) 3-/"!0$+334A%!'334"=#m2*)#2"#(%3+#0&()*=D#$&0560&()#92(%#(%)#-5#;20(&<)#2:#(%)#-32-)#&"-#(%)#&1'03(6-)#2: (%)#+3")?/&;)#+3<"&0#&'')&*3"<#&5*2++#3(=#E++61)#(%)#-32-)#(2#%&;)#S=N?T#-*2'#&(#,?1E#56**)"(= 10 V ID
R
R " VD
" vs
" !
rd
!
(a)
(b)
vd !
(c)
Figure 4.14 5(6# $3*563(# :2*# @A&1'0)# P=Z=# 5&6# $3*563(# :2*# 5&0560&(3"<# (%)# -5# 2')*&(3"<# '23"(=# 5*6# Y1&00?+3<"&0 )C63;&0)"(#53*563(=
4.3 Modeling the Diode Forward Characteristic
187
Solution $2"+3-)*3"<#-5#C6&"(3(3)+#2"048#/)#&++61)#@+#!#S=N#T#&"-#5&0560&()#(%)#-32-)#-5#56**)"( ,S ! S=N - + = ??????????????????? = S=UO#1E ,S Y3"5)#(%3+#;&06)#3+#;)*4#502+)#(2#,#1E8#(%)#-32-)#;20(&<)#/300#9)#;)*4#502+)#(2#(%)#&++61)-#;&06)#2: S=N#T=#E(#(%3+#2')*&(3"<#'23"(8#(%)#-32-)#3"5*)1)"(&0#*)+3+(&"5)#'*#3+# @ .Z ' * = ?????I? = ?????????? = .`=U#Ω S=UO -+ F%)# +3<"&0# ;20(&<)# &5*2++# (%)# -32-)# 5&"# 9)# :26"-# :*21# (%)# +1&00?+3<"&0# )C63;&0)"(# 53*563(# 3" L3<= P=,PB5D=# >)*)# v?# -)"2()+# (%)# `S?>M# ,?T# ')&H# +3"6+23-&0# 521'2")"(# 2:# @ +8# &"-# v*# 3+# (%)# 52*? *)+'2"-3"<#+3<"&0#&5*2++#(%)#-32-)=#h+3"<#(%)#;20(&<)?-3;3-)*#*60)#'*2;3-)+#(%)#')&H#&1'03(6-)#2:#v* &+#:2002/+Q '* ? v * # ( ')&H ) = @n? ????????????? , + '* S=S.`U = , ???????????????????????????? = .=`^ 1T # ,S + S=S.`U L3"&004#/)#"2()#(%&(#+3"5)#(%3+#;&06)#3+#C63()#+1&008#26*#6+)#2:#(%)#+1&00?+3<"&0#12-)0#2:#(%)#-32-)#3+ J6+(3:3)-=
L3"&0048#/)#"2()#(%&(#/%30)#'*#12-)0+#(%)#+1&00?+3<"&0#2')*&(32"#2:#(%)#-32-)#&(#02/#:*)C6)"? 53)+8#3(+#-4"&135#2')*&(32"#3+#12-)0)-#94#(%)#5&'&53(&"5)+#8O#&"-#8* 8#/%35%#/)#+(6-3)-#3"#Y)5? (32"#O=`#&"-#/%35%#&0+2#&*)#+1&00?+3<"&0#'&*&1)()*+=#E#521'0)()#12-)0#2:#(%)#-32-)#3"506-)+#8O &"-#8*03"#'&*&00)0#/3(%0'* =
4.3.8 Use of the Diode Forward Drop in Voltage Regulation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±,Sj#;&*3&(32"D8#(%) 52**)+'2"-3"<#*3''0)#3"#(%)#-32-)#;20(&<)#/&+#2"04#&926(#±.=N#1T#B±S=Pj#;&*3&(32"D=#[)<6? 0&()-#;20(&<)+#<*)&()*#(%&"#S=N#T#5&"#9)#29(&3")-#94#52"")5(3"<#"619)*#2:#-32-)+#3"#+)*3)+= L2*#)A&1'0)8#(%)#6+)#2:#(%*))#:2*/&*-?93&+)-#-32-)+#3"#+)*3)+#'*2;3-)+#20(&<)#2:#&926(#.#T= K")#+65%#53*563(#3+#3";)+(3<&()-#3"#(%)#:2002/3"<#)A&1'0)8#/%35%#6(303M)+#(%)#-32-)#+1&00?+3<"&0 12-)0#(2#C6&"(3:4#(%)#)::35&54#2:#(%)#;20(&<)#*)<60&(2*#(%&(#3+#*)&03M)-=
188 Chapter 4 Diodes
Example 4.6 $2"+3-)*#(%)#53*563(#+%2/"#3"#L3<=#P=,Z=#E#+(*3"<#2:#(%*))#-32-)+#3+#6+)-#(2#'*2;3-)#4"+(&"(#;20(&<) 2:#&926(#.=,#T=#I)#/&"(#(2#5&0560&()#(%)#')*5)"(&<)#5%&"<)#3"#(%3+#*)<60&()-#;20(&<)#5&6+)-#94#B&D#& ±,Sj#5%&"<)#3"#(%)#'2/)*?+6''04#;20(&<)#&"-#B9D#52"")5(32"#2:#,?HΩ#02&-#*)+3+(&"5)= 10) 1 V R = 1 k* " vO
RL = 1 k*
! Figure 4.15 $3*563(#:2*#@A&1'0)#P=`=
Solution I3(%#"2#02&-8#(%)#"213"&0#;&06)#2:#(%)#56**)"(#3"#(%)#-32-)#+(*3"<#3+#<3;)"#94# ,S ! .=, - = ??????????????????? = N=U#1E ID , F%6+#)&5%#-32-)#/300#%&;)#&"#3"5*)1)"(&0#*)+3+(&"5)#2: @ ' * = ?????I? I D F%6+8 .Z ' * = ??????? = O=.#Ω N=U
F%)#(%*))#-32-)+#3"#+)*3)+#/300#%&;)#(2(&0#3"5*)1)"(&0#*)+3+(&"5)#2:# ' = O' * = U=`#Ω
F%3+#*)+3+(&"5)8#&02"<#/3(%#(%)#*)+3+(&"5)#,8#:2*1+#20(&<)#-3;3-)*#/%2+)#*&(32#5&"#9)#6+)-#(2#5&0? 560&()#(%)#5%&"<)#3"#26('6(#;20(&<)#-6)#(2#±,Sj#B3=)=8#±,?TD#5%&"<)#3"#+6''04#;20(&<)=#F%6+#(%) ')&H?(2?')&H#5%&"<)#3"#26('6(#;20(&<)#/300#9)# ' S=SSU` this is ans to q cuz 3* ∆ v . = . ???????????? = . ????????????????????????? = ,U#1T ')&H?(2?')&H 0.7 voltage wont change '+, S=SSU` + , anyway
19mV /2 = 9.5
F%&(#3+8#52**)+'2"-3"<#(2#(%)#±,?T#B±,SjD#5%&"<)#3"#+6''04#;20(&<)8#(%)#26('6(#;20(&<)#/300#5%&"<) 94#±U=Z#1T#2*#±S=Zj=#Y3"5)#(%3+#31'03)+#%&"<)#2:#&926(#±O=.#1T#')*#-32-)8#26*#6+)#2:#(%)#+1&00? +3<"&0#12-)0#3+#J6+(3:3)-= I%)"# 02&-# *)+3+(&"5)# 2:# ,# HΩ# 3+# 52"")5()-# &5*2++# (%)# -32-)# +(*3"<8# 3(# -*&/+# 56**)"(# 2: &''*2A31&()04#.=,#1E=#F%6+#(%)#56**)"(#3"#(%)#-32-)+#-)5*)&+)+#94#.=,#1E8#*)+60(3"<#3"#-)5*)&+) 3"#;20(&<)#&5*2++#(%)#-32-)#+(*3"<#<3;)"#94 ∆ v . = ! .=, × ' = ! .=, × U=` = ! .S#1T
e x
4.4 Operation in the Reverse Breakdown Region—Zener Diodes
Y3"5)# (%3+# 31'03)+# (%&(# (%)# ;20(&<)# &5*2++# )&5%# -32-)# -)5*)&+)+# 94# &926(# `=N# 1T8# 26*# 6+)# 2:# (%) +1&00?+3<"&0# 12-)0# 3+# "2(# )"(3*)04# J6+(3:3)-=# X);)*(%)0)++8# -)(&30)-# 5&0560&(32"# 2:# (%)# ;20(&<) 5%&"<)#6+3"<#(%)#)A'2")"(3&0#12-)0#*)+60(+#3"# ∆ v . = ! .O#1T8 #/%35%#3+#"2(#(22#-3::)*)"(#:*21#(%) &''*2A31&()#;&06)#29(&3")-#6+3"<#(%)#3"5*)1)"(&0#12-)0=
EXERCISES 4.13# L3"-#(%)#;&06)#2:#(%)#-32-)#+1&00?+3<"&0#*)+3+(&"5)#'*#&(#93&+#56**)"(+#2:#S=,#1E8#,#1E8#&"-#,S#1E= Ans. .ZS#Ω7#.Z#Ω7#.=Z#Ω 4.14# $2"+3-)*#-32-)#93&+)-#&(#,#1E=#L3"-#(%)#5%&"<)#3"#56**)"(#&+#*)+60(#2:#5%&"<3"<#(%)#;20(&<) 94#B&D#−,S#1T8#B9D#−Z#1T8#B5D#+Z#1T8#&"-#B-D#+,S#1T=#!"#)&5%#5&+)8#-2#(%)#5&0560&(32"+#B3D#6+3"< (%)#+1&00?+3<"&0#12-)0#&"-#B33D#6+3"<#(%)#)A'2")"(3&0#12-)0= Ans. B&D#−S=PS8#−S=OO#1E; B9D#−S=.S8#−S=,^#1E; B5D#+S=.S8#+S=..#1E; B-D#+S=PS8#+S=PU#1E D4.15# R)+3<"#(%)#53*563(#2:#L3<=#@P=,Z#+2#(%&(#@.#=#O#T#/%)"#-P#=#S8#&"-#@.#5%&"<)+#94#.S#1T#')*#,#1E 2:#02&-#56**)"(=# B&D#h+)#(%)#+1&00?+3<"&0#12-)0#2:#(%)#-32-)#(2#:3"-#(%)#;&06)#2:#,= B9D#Y')53:4#(%)#;&06)#2:#-5002:#)&5%#2:#(%)#-32-)+= B5D#L2*#(%3+#-)+3<"8#6+)#(%)#-32-)#)A'2")"(3&0#12-)0#(2#-)()*13")#(%)#&5(6&0#5%&"<)#3"#@.#/%)"#& 56**)"(#-P#\#,#1E#3+#-*&/"#:*21#(%)#*)<60&(2*= "15 V
R VO IL
Figure E4.15
Ans. B&D%,#=#.=P#HΩ7#B9D%-5#\#P=N#+#,S!,`#E7%B5D%!..=O#1T%
4.4 Operation in the Reverse Breakdown Region—Zener Diodes F%)#;)*4#+())'#!]v#56*;)#(%&(#(%)#-32-)#)A%393(+#3"#(%)#9*)&H-2/"#*)<32"#BL3<=#P=^D#&"-#(%) &012+(?52"+(&"(#;20(&<)#-*2'#(%&(#(%3+#3"-35&()+8#+6<<)+(#(%&(#-32-)+#2')*&(3"<#3"#(%)#9*)&H-2/" *)<32"#5&"#9)#6+)-#3"#(%)#-)+3<"#2:#;20(&<)#*)<60&(2*+=#L*21#(%)#'*);326+#+)5(32"8#(%)#*)&-)*
189
190 Chapter 4 Diodes /300#*)5&00#(%&(#;20(&<)#*)<60&(2*+#&*)#53*563(+#(%&(#'*2;3-)#4"+(&"(#-5#26('6(#;20(&<)#3"#(%) :&5)#2:#5%&"<)+#3"#(%)3*#02&-#56**)"(#&"-#3"#(%)#+4+()1#'2/)*?+6''04#;20(&<)=#F%3+#3"#:&5(#(6*"+ 26(#(2#9)#&"#31'2*(&"(#&''035&(32"#2:#-32-)+#2')*&(3"<#3"#(%)#*);)*+)?9*)&H-2/"#*)<32"8#&"+')53&0#-32-)+#&*)#1&"6:&5(6*)-#(2#2')*&()#+')53:35&004#3"#(%)#9*)&H-2/"#*)<32"=#Y65%#-32-)+ &*)#5&00)-#&!"(>)-/1%)'-)"$#2*8#12*)#52112"048#&+#"2()-#)&*03)*8#B"1"!%)'-)"$= L3<6*)#P=,`#+%2/+#(%)#53*563(#+41920#2:#(%)#M)")*#-32-)=#!"#"2*1&0#&''035&(32"+#2:#M)")* -32-)+8#56**)"(#:02/+#3"(2#(%)#5&(%2-)8#&"-#(%)#5&(%2-)#3+#'2+3(3;)#/3(%#*)+')5(#(2#(%)#&"2-)= F%6+#-G#&"-#@G#3"#L3<=#P=,`#%&;)#'2+3(3;)#;&06)+= IZ
" VZ ! Figure 4.16 $3*563(# +41920# :2*# & M)")*#-32-)=
4.4.1 Specifying and Modeling the Zener Diode L3<6*)# P=,N# +%2/+# -)(&30+# 2:# (%)# -32-)# !]v# 5%&*&5()*3+(35# 3"# (%)# 9*)&H-2/"# *)<32"=# I) 29+)*;)#(%&(#:2*#56**)"(+#<*)&()*#(%&"#(%)#>1""%*+!!"1,#-GH#B+')53:3)-#2"#(%)#-&(+%))(#2: (%) M)")*# -32-)D8# (%)# !]v# 5%&*&5()*3+(35# 3+# &012+(# +(*&3<%(# 03")=# F%)# 1&"6:&5(6*)*# 6+6&004 +')53:3)+#(%)#;20(&<)#&5*2++#(%)#M)")*#-32-)#@G#&(#+')53:3)-#()+(#56**)"(8#-GI=#I)#%&;)#3"-3? 5&()-#(%)+)#'&*&1)()*+#3"#L3<=#P=,N#&+#(%)#522*-3"&()+#2:#(%)#'23"(#0&9)0)-#L=#F%6+#`=^?T i !VZ
!VZ 0
!VZK 0 !IZK
Slope '
,V
1 rz
Q
v
!IZT (test current)
,I
,V ' ,I rz Figure 4.17 F%)#-32-)#!]v#5%&*&5()*3+(35#/3(%#(%)#9*)&H-2/"#*)<32"#+%2/"#3"#+21)#-)(&30=
4.4 Operation in the Reverse Breakdown Region—Zener Diodes 191
M)")*#-32-)#/300#)A%393(#`=^?T#-*2'#&(#+')53:3)-#()+(#56**)"(#2:8#+&48#,S#1E=#E+#(%)#56*? *)"(# (%*26<%# (%)# M)")*# -);3&()+# :*21# -GI 8# (%)# ;20(&<)# &5*2++# 3(# /300# 5%&"<)8# (%26<%# 2"04 +03<%(04=#L3<6*)#P=,N#+%2/+#(%&(#52**)+'2"-3"<#(2#56**)"(#5%&"<)#∆-#(%)#M)")*#;20(&<)#5%&"<)+ 94#∆@8#/%35%#3+#*)0&()-#(2#∆-#94
∆@ = ' Q ∆/%)*)#'Q#3+#(%)#3";)*+)#2:#(%)#+02')#2:#(%)#&012+(?03")&*#!]v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o)")*#-32-)+#&*)#:&9*35&()-#/3(%#;20(&<)+#@G#3"#(%)#*&"<)#2:#:)/#;20(+#(2#:)/#%6"-*);20(+=#!"#&--3(32"#(2#+')53:43"<#@G#B&(#'&*(3560&*#56**)"(#-GID8#'Q8#&"-#-GH8#(%)#1&"6:&5(6*)* &0+2#+')53:3)+#(%)#1&A3161#'2/)*#(%&(#(%)#-);35)#5&"#+&:)04#-3++3'&()=#F%6+#& S=Z?I8#`=^?T M)")*# -32-)# 5&"# 2')*&()# +&:)04# &(# 56**)"(+# 6'# (2# 1&A3161# 2:# &926(# NS 1E= F%)# &012+(?03")&*# !]v# 5%&*&5()*3+(35# 2:# (%)# M)")*# -32-)# +6<<)+(+# (%&(# (%)# -);35)# 5&"# 9) 12-)0)-#&+#3"-35&()-#3"#L3<=#P=,^=#>)*)#@G S#-)"2()+#(%)#'23"(#&(#/%35%#(%)#+(*&3<%(#03")#2: +02')#, ⁄ ' Q#3"()*+)5(+#(%)#;20(&<)#&A3+#B*):)*#(2#L3<=#P=,ND=#E0(%26<%#@GS#3+#+%2/"#3"#L3<= P=,N (2#9)#+03<%(04#-3::)*)"(#:*21#(%)#H"))#;20(&<)#@GH8#3"#'*&5(35)#(%)3*#;&06)+#&*)#&012+(#)C6&0= F%)#)C63;&0)"(#53*563(#12-)0#2:#L3<=#P=,^#5&"#9)#&"&04(35&004#-)+5*39)-#94
@ G = @ GS + ' Q - G
BP=.SD
&"-#3(#&''03)+#:2*#-G#>#-GH#&"-8#29;326+048#@G#>#@G S=
Figure 4.18 m2-)0#:2*#(%)#M)")*#-32-)=
4.4.2 Use of the Zener as a Shunt Regulator I)#"2/#3006+(*&()8#94#/&4#2:#&"#)A&1'0)8#(%)#6+)#2:#M)")*#-32-)+#3"#(%)#-)+3<"#2:#+%6"(#*) 60&(2*+8#+2#"&1)-#9)5&6+)#(%)#*)<60&(2*#53*563(#&'')&*+#3"#'&*&00)0#B+%6"(D#/3(%#(%)#02&-=
192 Chapter 4 Diodes
Example 4.7 F%)# `=^?T# M)")*#-32-)#3"#(%)#53*563(#2:#L3<=#P=,UB&D#3+# +')53:3)-#(2#%&;)# @G#=#`=^#T#&(# -G#=#Z#1E8 'Q = .S#Ω8#&"-#-GH#=#S=.#1E=#F%)#+6''04#;20(&<)#@ +#3+#"213"&004#,S#T#96(#5&"#;&*4#94#±,#T= 1 V) I
IZ
6.8V Vz, ;IZ = 0.005mA; to calculate Vzo
"
IL
VO !
(b)
(a)
Figure 4.19 5(6#$3*563(#:2*#@A&1'0)#P=N=#5&6#F%)#53*563(#/3(%#(%)#M)")*#-32-)#*)'0&5)-#/3(%#3(+#)C63;&0)"(#53*563( 12-)0=
B&D L3"-#@.#/3(%#"2#02&-#&"-#/3(%#@ +#&(#3(+#"213"&0#;&06)= + B9D L3"-# (%)# 5%&"<)# 3"# @.# *)+60(3"<# :*21# (%)# ±,?T# 5%&"<)# 3"# @ +=# X2()# (%&(# ( ∆@ . ⁄ ∆ @ ) 8# 6+6&004 )A'*)++)-#3"#1T/T8#3+#H"2/"#&+#4'1"%!"7+4(,'-1= B5D L3"-#(%)#5%&"<)#3"#@.#*)+60(3"<#:*21#52"")5(3"<#&-#*)+3+(&"5)#,P#(%&(#-*&/+#8**)"(#-P#= , 1E8#&"-#%)"5)#:3"-#(%)#4-()%!"7+4(,'-1# ( ∆@ . ⁄ ∆- P ) #3"#1T/1E= B-D L3"-#(%)#5%&"<)#3"#@.#/%)"#,P#=#.#HΩ= B)D L3"-#(%)#;&06)#2:#@.#/%)"#,P#=#S=Z#HΩ= B:D I%&(#3+#(%)#13"3161#;&06)#2:#,P#:2*#/%35%#(%)#-32-)#+(300#2')*&()+#3"#(%)#9*)&H-2/"#*)<32"i Solution
Vz and IZ change depend on supply
L3*+(#/)#16+(#-)()*13")#(%)#;&06)#2:#(%)#'&*&1)()*#@G S#2:#(%)#M)")*#-32-)#12-)0=#Y69+(3(6(3"<#@G#= `=^#T8#-G#=#Z#1E8#&"-#'Q#=#.S#Ω#3"#@C=#BP=.SD#43)0-+# @ GS = `=N#T= #L3<6*)#P=,UB9D#+%2/+#(%)#53*563( /3(%#(%)#M)")*#-32-)#*)'0&5)-#/3(%#3(+#12-)0= B&D I3(%#"2#02&-#52"")5()-8#(%)#56**)"(#(%*26<%#(%)#M)")*#3+#<3;)"#94 + @ ! @ GS ? - G = - = ??????????????????? consider , + 'Q ,S ! `=N Text = ???????????????????????? = `=OZ#1E S=Z + S=S.
F%6+8 Vz=
@ . = @ GS + - G ' Q = `=N + `=OZ × S=S. = `=^O#T
this as ID in amp biais, even the rz exist already
4.4 Operation in the Reverse Breakdown Region—Zener Diodes 193
B9D L2*#±,?T#5%&"<)#3"#@ +8#(%)#5%&"<)#3"#26('6(#;20(&<)#5&"#9)#:26"-#:*21 + 'Q ? ∆@ . = ∆@ ????????????? , + 'Q .S = ± , × ????????????????????? = ± O^=Z#1T ZSS + .S
F%6+8 V3")#*)<60&(32"#=#O^=Z#1TaT
B5D I%)"#&-#*)+3+(&"5)#,P#(%&(#-*&/+#&-#56**)"(#-P#=#,#1E#3+#52"")5()-8#(%)#M)")*#56**)"( /300#-)5*)&+)#94#,#1E=#F%)#52**)+'2"-3"<#5%&"<)#3"#M)")*#;20(&<)#5&"#9)#:26"-#:*21 ∆@ . = ' Q ∆- G = .S × ! , = ! .S#1T
F%6+#(%)#02&-#*)<60&(32"#3+
e x a)
∆@ V2&-#*)<60&(32" ≡ ??????????. = ! .S#1Ta1E ∆- P
B-D I%)"# 02&-# *)+3+(&"5)# 2:# . HΩ# 3+# 52"")5()-8# (%)# 02&-# 56**)"(# /300# 9)# &''*2A31&()04 `=^ Ta. HΩ#=#O=P#1E=#F%6+#(%)#5%&"<)#3"#M)")*#56**)"(#/300#9)#∆-G#=#−O=P#1E8#&"-#(%)#52**)+'2"-? 3"<#5%&"<)#3"#M)")*#;20(&<)#B26('6(#;20(&<)D#/300#(%6+#9) ∆@ . = ' Q ∆- G
e x
e a) x
= .S × ! O=P = ! `^#1T
F%3+#5&0560&(32"8#%2/);)*8#3+#&''*2A31&()8#9)5&6+)#3(#")<0)5(+#(%)#5%&"<)#3"#(%)#56**)"(#-=#E#12*) &556*&()#)+(31&()#2:#∆@.#5&"#9)#29(&3")-#94#&"&04M3"<#(%)#53*563(#3"#L3<=#P=,UB9D=#F%)#*)+60(#2:#+65% &"#&"&04+3+#3+#∆@.#=#−NS#1T= B)D E"#,P#2:#S=Z#HΩ#/260-#-*&/#&-#56**)"(#2:# `=^ ⁄ S=Z#=#,O=`#1E=#F%3+#3+#"2(#'2++390)8#9)5&6+) (%)#56**)"(#-#+6''03)-#(%*26<%#,#3+#2"04#`=P#1E#B:2*#@ +#=#,S#TD=#F%)*):2*)8#(%)#M)")*#16+(#9)#56(#2::= !:#(%3+#3+#3"-))-#(%)#5&+)8#(%)"#@.#3+#-)()*13")-#94#(%)#;20(&<)#-3;3-)*#:2*1)-#94#,P#&"-#,#BL3<=#P=,U&D8
e x
!!!!!
+ ,P ? @ . = @ ??????????????? , + ,P
S=Z ? = Z#T = ,S ???????????????????? Text S=Z + S=Z
Y3"5)#(%3+#;20(&<)#3+#02/)*#(%&"#(%)#9*)&H-2/"#;20(&<)#2:#(%)#M)")*8#(%)#-32-)#3+#3"-))-#"2#02"<)* 2')*&(3"<#3"#(%)#9*)&H-2/"#*)<32"= B: D L2*#(%)#M)")*#(2#9)#&(#(%)#)-<)#2:#(%)#9*)&H-2/"#*)<32"8#-G#=#-GH#=#S=.#1E#&"-#@G#!#@GH#!#`=N T= E(#(%3+#'23"(#(%)#02/)+(#B/2*+(?5&+)D#56**)"(#+6''03)-#(%*26<%#,#3+#( U ! `=N ) ⁄ S=Z = P=`#1E8#&"-#(%6+ e (%)#02&-#56**)"(#3+#P=`#−#S=.#=#P=P#1E=#F%)#52**)+'2"-3"<#;&06)#2:#, P#3+
x
`=N , P = ??????? ! ,=Z#HΩ P=P
e x
should give diod 0.2 mA even after "drawn current by add RL"
e x
= Vzo!!!
or 9- vzo - izk*rz ok too (see prolem e set)
x
194 Chapter 4 Diodes
4.4.3 Temperature Effects F%)#-)')"-)"5)#2:#(%)#M)")*#;20(&<)#@G#2"#()1')*&(6*)#3+#+')53:3)-#3"#()*1+#2:#3(+#,"=3"!(0 ,+!"% *-"..'*'"1,%CD8#2*# ,"=*-#&+#3(# 3+#52112"04# H"2/"8#/%35%#3+# 6+6&004#)A'*)++)-#3" 1Ta°$=#F%)#;&06)#2:#F$#-)')"-+#2"#(%)#M)")*#;20(&<)8#&"-#:2*#<3;)"#-32-)#(%)#F$#;&*3)+ /3(%#(%)#2')*&(3"<#56**)"(=#o)")*#-32-)+#/%2+)#@G#&*)#02/)*#(%&"#&926(#Z#T#)A%393(#")<&? (3;)#F$=#K"#(%)#2(%)*#%&"-8#M)")*+#/3(%#%3<%)*#;20(&<)+#)A%393(#'2+3(3;)#F$=#F%)#F$#2:#& M)")*#-32-)#/3(%#@G#2:#&926(#Z#T#5&"#9)#1&-)#M)*2#94#2')*&(3"<#(%)#-32-)#&(#+')53:3)56**)"(=#E"2(%)*#52112"04#6+)-#()5%"3C6)#:2*#29(&3"3"<#*):)*)"5)#;20(&<)#/3(%#02/#()1? ')*&(6*)# 52)::353)"(# 3+# (2# 52"")5(# M)")*# -32-)# /3(%# '2+3(3;)# ()1')*&(6*)# 52)::353)"(# 2: &926(# .# 1Ta°$# 3"# +)*3)+# /3(%# :2*/&*-?52"-65(3"<# -32-)=# Y3"5)# (%)# :2*/&*-?52"-65(3"< -32-)#%&+#20(&<)#-*2'#2:#!S=N#T#&"-#F$#2:#&926(#−.#1Ta°$8#(%)#+)*3)+#52193"&(32" /300#'*2;3-)#20(&<)#2:#B@G#+#S=ND#/3(%#F$#2:#&926(#M)*2=
EXERCISES 4.16# E#M)")*#-32-)#/%2+)#"213"&0#;20(&<)#3+#,S#T#&(#,S#1E#%&+#&"#3"5*)1)"(&0#*)+3+(&"5)#2:#ZS#Ω=#I%&( ;20(&<)#-2#426#)A')5(#3:#(%)#-32-)#56**)"(#3+#%&0;)-i#R2690)-i#I%&(#3+#(%)#;&06)#2:#@GS#3"#(%)#M)")* 12-)0i Ans. U=NZ#T7#,S=Z#T7#U=Z#T 4.17# E#M)")*#-32-)#)A%393(+#4"+(&"(#;20(&<)#2:#Z=`#T#:2*#56**)"(+#<*)&()*#(%&"#:3;)#(31)+#(%)#H"))#56*? *)"(=#-GH#3+#+')53:3)-#(2#9)#,#1E=#F%)#M)")*#3+#(2#9)#6+)-#3"#(%)#-)+3<"#2:#+%6"(#*)<60&(2*#:)-#:*21 ,Z?T#+6''04=#F%)#02&-#56**)"(#;&*3)+#2;)*#(%)#*&"<)#2:#S#1E#(2#,Z#1E=#L3"-#+63(&90)#;&06)#:2*#(%) *)+3+(2*#,=#I%&(#3+#(%)#1&A3161#'2/)*#-3++3'&(32"#2:#(%)#M)")*#-32-)i Ans. PNS#Ω7#,,.#1I 4.18# E#+%6"(#*)<60&(2*#6(303M)+#M)")*#-32-)#/%2+)#;20(&<)#3+#Z=,#T#&(#8**)"(#2:#ZS#1E#&"-#/%2+) 3"5*)1)"(&0#*)+3+(&"5)#3+#N#Ω=#F%)#-32-)#3+#:)-#:*21#+6''04#2:#,Z?T#"213"&0#;20(&<)#(%*26<%#.SS? Ω#*)+3+(2*=#I%&(#3+#(%)#26('6(#;20(&<)#&(#"2#02&-i#L3"-#(%)#03")#*)<60&(32"#&"-#(%)#02&-#*)<60&(32"= Ans. Z=,#T7#OO=^#1TaT7#−N#1Ta1E
4.4.4 A Final Remark F%26<%#+31'0)#&"-#6+):608#M)")*#-32-)+#%&;)#02+(#<*)&(#-)&0#2:#(%)3*#'2'60&*3(4#3"#*)5)"( 4)&*+=#F%)4#%&;)#9))"#;3*(6&004#*)'0&5)-#3"#;20(&<)?*)<60&(2*#-)+3<"#94#+')53&004#-)+3<")3"()<*&()-#53*563(+#B!$+D#(%&(#')*:2*1#(%)#;20(&<)#*)<60&(32"#:6"5(32"#165%#12*)#)::)5(3;)04 &"-#/3(%#<*)&()*#:0)A39303(4#(%&"#M)")*#-32-)+=
4.5 Rectifier Circuits K")# 2:# (%)# 12+(# 31'2*(&"(# &''035&(32"+# 2:# -32-)+# 3+# 3"# (%)# -)+3<"# 2:# *)5(3:3)*# 53*563(+=# E -32-)#*)5(3:3)*#:2*1+#&"#)++)"(3&0#9630-3"<#9025H#2:#(%)#-5#'2/)*#+6''03)+#*)C63*)-#(2#'2/)* )0)5(*2"35#)C63'1)"(=#E#9025H#-3&<*&1#2:#+65%#'2/)*#+6''04#3+#+%2/"#3"#L3<=#P=.S=#E+ 3"-35&()-8#(%)#'2/)*#+6''04#3+#:)-#:*21#(%)#,.S?T#B*1+D#`S?>M#&5#03")8#&"-#3(#-)03;)*+#-5 ;20(&<)#@.#B6+6&004#3"#(%)#*&"<)#2:#Z#T#(2#.S#TD#(2#&"#)0)5(*2"35#53*563(#*)'*)+)"()-#94#(%)
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4.5.1 The Half-Wave Rectifier F%)#%&0:?/&;)#*)5(3:3)*#6(303M)+#&0()*"&()#%&0:?5450)+#2:#(%)#3"'6(#+3"6+23-=#L3<6*)#P=.,B&D +%2/+# (%)# 53*563(# 2:# %&0:?/&;)# *)5(3:3)*=# F%3+# 53*563(# /&+# &"&04M)-# 3"# Y)5(32"# P=,# B+)) L3<=# P=OD# &++613"<# &"# 3-)&0# -32-)=# h+3"<# (%)# 12*)# *)&03+(35# 52"+(&"(?;20(&<)?-*2'# -32-) 12-)08#/)#29(&3"# v.#\#S8
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EXERCISE 4.19#L2*#(%)#%&0:?/&;)#*)5(3:3)*#53*563(#3"#L3<=#P=.,B&D8#+%2/#(%)#:2002/3"
4.5.2 The Full-Wave Rectifier F%)#:600?/&;)#*)5(3:3)*#6(303M)+#92(%#%&0;)+#2:#(%)#3"'6(#+3"6+23-=#F2#'*2;3-)#"3'20&*#26(? '6(8#3(#3";)*(+#(%)#")<&(3;)#%&0;)+#2:#(%)#+3")#/&;)=#K")#'2++390)#31'0)1)"(&(32"#3+#+%2/"#3" L3<=#P=..B&D=#>)*)#(%)#(*&"+:2*1)*#+)52"-&*4#/3"-3"<#3+#*"1,"!0,(33")#(2#'*2;3-)#(/2#)C6&0 ;20(&<)+# v5# &5*2++# (%)# (/2# %&0;)+# 2:# (%)# +)52"-&*4# /3"-3"<# /3(%# (%)# '20&*3(3)+# 3"-35&()-= X2()#(%&(#/%)"#(%)#3"'6(#03")#;20(&<)#B:))-3"<#(%)#'*31&*4D#3+#'2+3(3;)8#92(%#2:#(%)#+3<"&0+ 0&9)0)-#v5#/300#9)#'2+3(3;)=#!"#(%3+#5&+)#+,#/300#52"-65(#&"-#+.#/300#9)#*);)*+)#93&+)-=#F%) 56**)"(#(%*26<%#+,#/300#:02/#(%*26<%#,#&"-#9&5H#(2#(%)#5)"()*#(&'#2:#(%)#+)52"-&*4=#F%)#53*? 563(#(%)"#9)%&;)+#03H)#%&0:?/&;)#*)5(3:3)*8#&"-#(%)#26('6(#-6*3"<#(%)#'2+3(3;)#%&0:?5450)+ /%)"#+,#52"-65(+#/300#9)#3-)"(35&0#(2#(%&(#'*2-65)-#94#(%)#%&0:?/&;)#*)5(3:3)*= X2/8#-6*3"<#(%)#")<&(3;)#%&0:?5450)#2:#(%)#&5#03")#;20(&<)8#92(%#2:#(%)#;20(&<)+#0&9)0)-#v5 /300#9)#")<&(3;)=#F%6+#+,#/300#9)#56(#2::#/%30)#+.#/300#52"-65(=#F%)#56**)"(#52"-65()-#94#+. /300#:02/#(%*26<%#,#&"-#9&5H#(2#(%)#5)"()*#(&'=#!(#:2002/+#(%&(#-6*3"<#(%)#")<&(3;)#%&0:?5450)+ /%30)#+.#52"-65(+8#(%)#53*563(#9)%&;)+#&<&3"#&+#%&0:?/&;)#*)5(3:3)*=#F%)#31'2*(&"(#'23"(8 %2/);)*8#3+#(%&(#(%)#56**)"(#(%*26<%#,#&0/&4+#:02/+#3"#(%)#+&1)#-3*)5(32"8#&"-#(%6+#v.#/300 9)#6"3'20&*8#&+#3"-35&()-#3"#L3<=#P=..B5D=#F%)#26('6(#/&;):2*1#+%2/"#3+#29(&3")-#94#&++61? 3"<#(%&(#4"-65(3"<#-32-)#%&+#4"+(&"(#;20(&<)#-*2'#@+=#F%6+#(%)#(*&"+:)*#5%&*&5()*3+(35 2:#(%)#:600?/&;)#*)5(3:3)*#(&H)+#(%)#+%&')#+%2/"#3"#L3<=#P=..B9D= F%)#:600?/&;)#*)5(3:3)*#29;326+04#'*2-65)+#*)#e)")*<)(35f#/&;):2*1#(%&"#(%&(#'*2? ;3-)-#94#(%)#%&0:?/&;)#*)5(3:3)*=#!"#&012+(#&00#*)5(3:3)*#&''035&(32"+8#2")#2'(+#:2*#:600?/&;) (4')#2:#+21)#H3"-=
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199
200 Chapter 4 Diodes X)A(8#52"+3-)*#(%)#+3(6&(32"#-6*3"<#(%)#")<&(3;)#%&0:?5450)+#2:#(%)#3"'6(#;20(&<)=#F%)#+)5? 2"-&*4#;20(&<)#v5#/300#9)#")<&(3;)8#&"-#(%6+#−v5#/300#9)#'2+3(3;)8#:2*53"<#56**)"(#(%*26<%#+O8 ,8#&"-#+P=#m)&"/%30)8#-32-)+#+,#&"-#+.#/300#9)#*);)*+)#93&+)-=#F%)#31'2*(&"(#'23"(#(2#"2()8 (%26<%8#3+#(%&(#-6*3"<#92(%#%&0:?5450)+8#56**)"(#:02/+#(%*26<%#,#3"#(%)#+&1)#-3*)5(32"#B:*21 *3<%(#(2#0):(D8#&"-#(%6+#v.#/300#&0/&4+#9)#'2+3(3;)8#&+#3"-35&()-#3"#L3<=#P=.OB9D= F2#-)()*13")#(%)#')&H#3";)*+)#;20(&<)#Bl!TD#2:#)&5%#-32-)8#52"+3-)*#(%)#53*563(#-6*3"< (%)# '2+3(3;)# %&0:?5450)+=# F%)# *);)*+)# ;20(&<)# &5*2++# +O# 5&"# 9)# -)()*13")-# :*21# (%)# 022' :2*1)-#94#+O8#,8#&"-#+.#&+ v +O # ( *);)*+) ) = v . + v +. # ( :2*/&*- ) F%6+#(%)#1&A3161#;&06)#2:#v+O#2556*+#&(#(%)#')&H#2:#v.#&"-#3+#<3;)"#94
l!T = @ ? ! .@ + + @ + = @ ? ! @ + K9+)*;)#(%&(#%)*)#(%)#l!T#3+#&926(#%&0:#(%)#;&06)#:2*#(%)#:600?/&;)#*)5(3:3)*#/3(%#)"()*? (&'')-#(*&"+:2*1)*=#F%3+#3+#&"2(%)*#&-;&"(&<)#2:#(%)#9*3-<)#*)5(3:3)*= p)(#2")#12*)#&-;&"(&<)#2:#(%)#9*3-<)#*)5(3:3)*#53*563(#2;)*#(%&(#6(303M3"<#)"()*?(&'')(*&"+:2*1)*#3+#(%&(#2"04#&926(#%&0:#&+#1&"4#(6*"+#&*)#*)C63*)-#:2*#(%)#+)52"-&*4#/3"-3"<#2:#(%) (*&"+:2*1)*=#E"2(%)*#/&4#2:#022H3"<#&(#(%3+#'23"(#5&"#9)#29(&3")-#94#29+)*;3"<#(%&(#)&5%#%&0:#2: (%)#+)52"-&*4#/3"-3"<#2:#(%)#5)"()*?(&'')-#(*&"+:2*1)*#3+#6(303M)-#:2*#2"04#%&0:#(%)#(31)=#F%)+) &-;&"(&<)+#%&;)#1&-)#(%)#9*3-<)#*)5(3:3)*#(%)#12+(#'2'60&*#*)5(3:3)*#53*563(#52":3<6*&(32"=
EXERCISE 4.21#L2*#(%)#9*3-<)#*)5(3:3)*#53*563(#2:#L3<=#P=.OB&D8#6+)#(%)#52"+(&"(?;20(&<)?-*2'#-32-)#12-)0#(2#+%2/#(%&(#B&D (%)# &;)*&<)# B2*# -5# 521'2")"(D# 2:# (%)# 26('6(# ;20(&<)# 3+# @ . # ! # ( . ⁄ π )@ ? ! .@ + # &"-# B9D# (%)# ')&H -32-)#56**)"(#3+#( @ ? ! .@ + ) ⁄ , )=#L3"-#"61)*35&0#;&06)+#:2*#(%)#C6&"(3(3)+#3"#B&D#&"-#B9D#&"-#(%)#l!T :2*#(%)#5&+)#3"#/%35%#v5#3+#,.?T#B*1+D#+3"6+23-8#@+#!#S=N#T8#&"-#,#=#,SS#Ω. Ans. U=P#T7#,Z`#1E7#,`=O#T
4.5.4 The Rectifier with a Filter Capacitor—The Peak Rectifier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v-#9)#+3"6+23-#/3(%#')&H#;&06)#@#8#&"-#&++61)#(%) -32-)#(2#9)#3-)&0=#E+#v-#<2)+#'2+3(3;)8#(%)#-32-)#52"-65(+#&"-#(%)#5&'&53(2*#3+#5%&*<)-#+2#(%&( v.# =# v-=# F%3+# +3(6&(32"# 52"(3"6)+# 6"(30# v-# *)&5%)+# 3(+# ')&H# ;&06)# @#=# _)42"-# (%)# ')&H8# &+# v-)5*)&+)+#(%)#-32-)#9)521)+#*);)*+)#93&+)-#&"-#(%)#26('6(#;20(&<)#*)1&3"+#52"+(&"(#&(#(%) ;&06)#@#=#!"#:&5(8#(%)2*)(35&004#+')&H3"<8#(%)#5&'&53(2*#/300#*)(&3"#3(+#5%&*<)#&"-#%)"5)#3(+#;20(? &<)#3"-):3"3()048#9)5&6+)#(%)*)#3+#"2#/&4#:2*#(%)#5&'&53(2*#(2#-3+5%&*<)=#F%6+#(%)#53*563(#'*2? ;3-)+#-5#;20(&<)#26('6(#)C6&0#(2#(%)#')&H#2:#(%)#3"'6(#+3")#/&;)=#F%3+#3+#)*4#)"526*&<3"< *)+60(#3"#;3)/#2:#26*#-)+3*)#(2#'*2-65)#-5#26('6(=
4.5 Rectifier Circuits 201
D
(a)
0
(b) Figure 4.24 5(6# E# +31'0)# 53*563(# 6+)-# (2# 3006+(*&()# (%)# )::)5(# 2:# :30()*# 5&'&53(2*=# 5&6# !"'6(# &"-# 26('6( /&;):2*1+#&++613"<#&"#3-)&0#-32-)=#X2()#(%&(#(%)#53*563(#'*2;3-)+#-5#;20(&<)#)C6&0#(2#(%)#')&H#2:#(%)#3"'6( +3")#/&;)=#F%)#53*563(#3+#(%)*):2*)#H"2/"#&+##3)A0'3/4!%!3'#2*##3)A0*343/4&'=
X)A(8# /)# 52"+3-)*# (%)# 12*)# '*&5(35&0# +3(6&(32"# /%)*)# 02&-# *)+3+(&"5)# ,# 3+# 52"")5()&5*2++#(%)#5&'&53(2*#88#&+#-)'35()-#3"#L3<=#P=.ZB&D=#>2/);)*8#/)#/300#52"(3"6)#(2#&++61) (%)#-32-)#(2#9)#3-)&0=#E+#9):2*)8#:2*#+3"6+23-&0#3"'6(8#(%)#5&'&53(2*#5%&*<)+#(2#(%)#')&H#2: (%)#3"'6(#@#=#F%)"#(%)#-32-)#56(+#2::8#&"-#(%)#5&'&53(2*#-3+5%&*<)+#(%*26<%#(%)#02&-#*)+3+(&"5) ,=#F%)#5&'&53(2*#-3+5%&*<)#/300#52"(3"6)#:2*#&012+(#(%)#)"(3*)#5450)8#6"(30#(%)#(31)#&(#/%35%#v)A5))-+#(%)#5&'&53(2*#;20(&<)=#F%)"#(%)#-32-)#(6*"+#2"#&<&3"#&"-#5%&*<)+#(%)#5&'&53(2*#6'#(2 (%)#')&H#2:#v- 8#&"-#(%)#'*25)++#*)')&(+#3(+)0:=#K9+)*;)#(%&(#(2#H))'#(%)#26('6(#;20(&<)#:*21 -)5*)&+3"<#(22#165%#-6*3"<#5&'&53(2*#-3+5%&*<)8#2")#+)0)5(+#&06)#:2*#8#+2#(%&(#(%)#(31) 52"+(&"(#8,#3+#165%#<*)&()*#(%&"#(%)#-3+5%&*<)#3"()*;&0=# I)#&*)#"2/#*)&-4#(2#&"&04M)#(%)#53*563(#3"#-)(&30=#L3<6*)#P=.ZB9D#+%2/+#(%)#+()&-4?+(&() 3"'6(#&"-#26('6(#;20(&<)#/&;):2*1+#6"-)*#(%)#&++61'(32"#(%&(#8,#%#I8#/%)*)#I#3+#(%)#')*322:#(%)#3"'6(#+3"6+23-=#F%)#/&;):2*1+#2:#(%)#02&-#56**)"(
!P = v. ⁄ ,
BP=.OD
&"-#2:#(%)#-32-)#56**)"(#B/%)"#3(#3+#52"-65(3"
!+ = !8 + !P *v = 8 ???????- + ! P *4
BP=.PD BP=.ZD
202 Chapter 4 Diodes iD D
iC
vI " !
"
iL R
C
vO !
(a) T vO Vr Vp
vI
vI ,t
t1
t2
t
Conduction interval ,t
(b)
,t
iD derivative V0 which is vs
iL
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t
Figure 4.25 T20(&<)# &"-# 56**)"(# /&;):2*1+# 3"# (%)# ')&H# *)5(3:3)*# 53*563(# /3(%# 8,# %# I=# F%)# -32-)# 3+ &++61)-#3-)&0=
&*)#+%2/"#3"#L3<=#P=.ZB5D=#F%)#:2002/3"<#29+)*;&(32"+#&*)#3"#2*-)*Q F%)#-32-)#52"-65(+#:2*# *3):#3"()*;&08#∆48#")&*#(%)#')&H#2:#(%)#3"'6(#+3"6+23-#&"+6''03)+# (%)# 5&'&53(2*# /3(%# 5%&*<)# )C6&0# (2# (%&(# 02+(# -6*3"<# (%)# 165%# 02"<)*# -3+? 5%&*<)#3"()*;&0=#F%)#0&(()*#3+#&''*2A31&()04#)C6&0#(2#(%)#')*32-#I= 2. E++613"<#&"#3-)&0#-32-)8#(%)#-32-)#52"-65(32"#9)<3"+#&(#(31)#4,8#&(#/%35%#(%)#3"'6(#v)C6&0+#(%)#)A'2")"(3&004#-)5&43"<#26('6(#v.=#$2"-65(32"#+(2'+#&(#4.#+%2*(04#&:()*#(%) ')&H#2:#v- 7#(%)#)A&5(#;&06)#2:#4.#5&"#9)#-)()*13")-#94#+)((3"<#!+#=#S#3"#@C=#BP=.ZD= 1.
4.5 Rectifier Circuits 203
R6*3"<# (%)# -32-)?2::# 3"()*;&08# (%)# 5&'&53(2*# 8# -3+5%&*<)+# (%*26<%# ,8# &"-# (%6+# v. -)5&4+# )A'2")"(3&004# /3(%# (31)# 52"+(&"(# 8,=# F%)# -3+5%&*<)# 3"()*;&0# 9)<3"+# J6+( '&+(#(%)#')&H#2:#v-=#E(#(%)#)"-#2:#(%)#-3+5%&*<)#3"()*;&08#/%35%#0&+(+#:2*#&012+(#(%) )"(3*)# ')*32-# I8# v.# =# @## −# @' 8# /%)*)# @'# 3+# (%)# ')&H?(2?')&H# *3''0)# ;20(&<)=# I%)" 8, %#I8#(%)#;&06)#2:#@'#3+#+1&00= 4. I%)"#@'#3+#+1&008#v.#3+#&012+(#52"+(&"(#&"-#)C6&0#(2#(%)#')&H#;&06)#2:#v-=#F%6+#(%)#-5 26('6(#;20(&<)#3+#&''*2A31&()04#)C6&0#(2#@#=#Y3130&*048#(%)#56**)"(#!P#3+#&012+(#52"? +(&"(8#&"-#3(+#-5#521'2")"(#-P#3+#<3;)"#94 3.
@# - P = ????? ,
BP=.`D
!:#-)+3*)-8#*)#&556*&()#)A'*)++32"#:2*#(%)#26('6(#-5#;20(&<)#5&"#9)#29(&3")-#94 (&H3"<#(%)#&;)*&<)#2:#(%)#)A(*)1)#;&06)+#2:#v.8
@ . = @ # ! ,??.? @ '
BP=.ND
I3(%#(%)+)#29+)*;&(32"+#3"#%&"-8#/)#"2/#-)*3;)#)A'*)++32"+#:2*#@'#&"-#:2*#(%)#&;)*&<) &"-#')&H#;&06)+#2:#(%)#-32-)#56**)"(=#R6*3"<#(%)#-32-)?2::#3"()*;&08#v.#5&"#9)#)A'*)++)-#&+ v. = @# 3
! 4 ⁄ 8,
E(#(%)#)"-#2:#(%)#-3+5%&*<)#3"()*;&0#/)#%&;)
@ # ! @ ' # ! #@ # 3
! I ⁄ 8,
X2/8#+3"5)#8,#%#I8#/)#5&"#6+)#(%)#&''*2A31&(32"# 3
! I ⁄ 8,
! , ! I ⁄ 8, (2#29(&3"
I @ ' ! @ # ???????? 8,
BP=.^D
I)#29+)*;)#(%&(#(2#H))'#@'#+1&00#/)#16+(#+)0)5(#&'&53(&"5)#8#+2#(%&(#8,#%#I=#F%)#!'334" #-4,(7"#@'#3"#@C=#BP=.^D#5&"#9)#)A'*)++)-#3"#()*1+#2:#(%)#:*)C6)"54# % = , ⁄ I &+
@# @ ' = ?????????? %8,
BP=.U&D
h+3"<#@C=#BP=.`D#/)#5&"#)A'*)++#@'#94#(%)#&0()*"&()#)A'*)++32"
@ ' = ?????P? %8
BP=.U9D
X2()#(%&(#&"#&0()*"&(3;)#3"()*'*)(&(32"#2:#(%)#&''*2A31&(32"#1&-)#&92;)#3+#(%&(#(%)#5&'&53(2* -3+5%&*<)+#94#1)&"+#2:#4"+(&"(#56**)"(# - P = @ # ⁄ ,=#F%3+#&''*2A31&(32"#3+#;&03-#&+#02"< &+#@' ( @#= E++613"<#(%&(#-32-)#52"-65(32"#5)&+)+#&012+(#&(#(%)#')&H#2:#v- 8#/)#5&"#-)()*13")#(%) *-1)+*,'-1%'1,"!#(4#∆4#:*21
@ # 52+ ( ω ∆4 ) = @ # ! @ ' /%)*)# ω = . π % = . π ⁄ I 3+#(%)#&"<60&*#:*)C6)"54#2:#v- =#Y3"5)#Bω ∆4D#3+#+1&00#&"<0)8#/) . 5&"#)1'024#(%)#&''*2A31&(32"# 52+ ( ω ∆4 ) ! , ! ,??.? ( ω ∆4 ) #(2#29(&3"
ω ∆4# ! .@ ' ⁄ @ # I)#"2()#(%&(#/%)"#@'#(#@#8#(%)#52"-65(32"#&"<0)#ω ∆4#/300#9)#+1&008#&+#&++61)-=
BP=OSD
204 Chapter 4 Diodes F2# -)()*13")# (%)# &;)*&<)# -32-)# 56**)"(# -6*3"<# 52"-65(32"8# !+&;8# /)# )C6&()# (%)# 5%&*<) (%&(#(%)#-32-)#+6''03)+#(2#(%)#5&'&53(2*8
L +6''03)- = ! 8&; ∆4 /%)*)#:*21#@C=#BP=.PD8
! 8&; = ! +&; ! - P
(2#(%)#5%&*<)#(%&(#(%)#5&'&53(2*#02+)+#-6*3"<#(%)#-3+5%&*<)#3"()*;&08
L 02+( = 8@ ' (2#29(&3"8#6+3"<#@C+=#BP=OSD#&"-#BP=.U&D8
! +&; = - P ( , + π .@ # ⁄ @ ' )
BP=O,D
K9+)*;)#(%&(#/%)"#@'#(#@#8#(%)#&;)*&<)#-32-)#56**)"(#-6*3"<#52"-65(32"#3+#165%# <*)&()* (%&"# (%)# -5# 02&-# 56**)"(=# F%3+# 3+# "2(# +6*'*3+3"<8# +3"5)# (%)# -32-)# 52"-65(+# :2*# ;)*4# +%2*( 3"()*;&0#&"-#16+(#*)'0)"3+%#(%)#5%&*<)#02+(#94#(%)#5&'&53(2*#-6*3"<#(%)#165%#02"<)*#3"()*;&0 3"#/%35%#3(#3+#-3+5%&*<)-#94#-P= F%)#')&H#;&06)#2:#(%)#-32-)#56**)"(8#!+1&A8#5&"#9)#-)()*13")-#94#);&06&(3"<#(%)#)A'*)+? +32"#3"#@C=#BP=.ZD#&(#(%)#2"+)(#2:#-32-)#52"-65(32"W(%&(#3+8#&(#4#=#4,#=#−∆4#B/%)*)#4#=#S#3+#&(#(%) ')&HD=#E++613"<#(%&(#!P#3+#&012+(#52"+(&"(#&(#(%)#;&06)#<3;)"#94#@C=#BP=.`D8#/)#29(&3"
! +1&A = - P ( , + . π .@ # ⁄ @ ' )
BP=O.D
L*21#@C+=#BP=O,D#&"-#BP=O.D8#/)#+))#(%&(#:2*#@'#(#@#8#!+1&A#!#.!+&;8#/%35%#52**)0&()+#/3(%#(%) :&5(#(%&(#(%)#/&;):2*1#2:#!+#3+#&012+(#*3<%(?&"<0)#(*3&"<0)#B+))#L3<=#P=.Z5D=
Example 4.8 $2"+3-)*#')&H#*)5(3:3)*#:)-#94#`S?>M#+3"6+23-#%&;3"<#')&H#;&06)#@##=#,SS#T=#V)(#(%)#02&-#*)+3+? (&"5)#,#=#,S#HΩ=#L3"-#(%)#;&06)#2:#(%)#5&'&53(&"5)#8#(%&(#/300#*)+60(#3"#')&H?(2?')&H#*3''0)#2:#.#T= E0+28#5&0560&()#(%)#:*&5(32"#2:#(%)#5450)#-6*3"<#/%35%#(%)#-32-)#3+#52"-65(3"<#&"-#(%)#&;)*&<)#&"')&H#;&06)+#2:#(%)#-32-)#56**)"(= Solution L*21#@C=#BP=.U&D#/)#29(&3"#(%)#;&06)#2:#8#&+ @# ,SS 8 = ???????????? = ?????????????????????????????????????????O? = ^O=O#µL @ ' %, . × `S × ,S × ,S F%)#52"-65(32"#&"<0)#ω#∆4#3+#:26"-#:*21#@C=#BP=OSD#&+
ω ∆4 =
. × . ⁄ ,SS = S=.#*&-
F%6+# (%)# -32-)# 52"-65(+# :2*# ( S=. ⁄ . π ) × ,SS = O=,^j 2:# (%)# 5450)=# F%)# &;)*&<)# -32-)# 56**)"(# 3+ 29(&3")-#:*21#@C=#BP=O,D8#/%)*)# - P = ,SS ⁄ ,S = ,S#1E8 &+ ! +&; = ,S ( , + π . × ,SS ⁄ . ) = O.P#1E
F%)#')&H#-32-)#56**)"(#3+#:26"-#6+3"<#@C=#BP=O.D8 ! +1&A = ,S ( , + . π . × ,SS ⁄ . ) = `O^#1E
4.5 Rectifier Circuits 205
Figure 4.26 I&;):2*1+#3"#(%)#:600?/&;)#')&H#*)5(3:3)*=
F%)#53*563(#2:#L3<=#P=.ZB&D#3+#H"2/"#&+#%&0:?/&;)#3"(>%!"*,'.'"!=#F%)#:600?/&;)#*)5(3? :3)*#53*563(+#2:#L3<+=#P=..B&D#&"-#P=.OB&D#5&"#9)#52";)*()-#(2#')&H#*)5(3:3)*+#94#3"506-3"<#& 5&'&53(2*# &5*2++# (%)# 02&-# *)+3+(2*=# E+# 3"# (%)# %&0:?/&;)# 5&+)8# (%)# 26('6(# -5# ;20(&<)# /300# 9) &012+(#)C6&0#(2#(%)#')&H#;&06)#2:#(%)#3"'6(#+3")#/&;)#BL3<=#P=.`D=#F%)#*3''0)#:*)C6)"548#%2/? );)*8#/300#9)#(/35)#(%&(#2:#(%)#3"'6(=#F%)#')&H?(2?')&H#*3''0)#;20(&<)8#:2*#(%3+#5&+)8#5&"#9) -)*3;)-#6+3"<#'*25)-6*)#3-)"(35&0#(2#(%&(#&92;)#96(#/3(%#(%)#-3+5%&*<)#')*32-#I#*)'0&5)-#94 I ⁄ . 8#*)+60(3"<#3"
@# @ ' = ????????????? .%8,
BP=OOD
I%30)#(%)#-32-)#52"-65(32"#3"()*;&08#∆48#/300#+(300#9)#<3;)"#94#@C=#BP=OSD8#(%)#&;)*&<)#&"')&H#56**)"(+#3"#)&5%#2:#(%)#-32-)+#/300#9)#<3;)"#94
! +&; = - P ( , + π @ # ⁄ .@ ' )
BP=OPD
! +1&A = - P ( , + . π @ # ⁄ .@ ' )
BP=OZD
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−#@+D#:2*#(%)#%&0:?/&;)#53*563(#&"-#(%)#:600?/&;)#53*? 563(#6+3"<#)"()*?(&'')-#(*&"+:2*1)*#&"-#/3(%#B@##−#.@+D#:2*#(%)#9*3-<)?*)5(3:3)*#5&+)= I)#52"506-)#(%3+#+)5(32"#94#"2(3"<#(%&(#')&H?*)5(3:3)*#53*563(+#:3"-#&''035&(32"#3"#+3<"&0? '*25)++3"<#+4+()1+#/%)*)#3(#3+#*)C63*)-#(2#-)()5(#(%)#')&H#2:#&"#3"'6(#+3<"&0=#!"#+65%#&+)8 (%)#53*563(#3+#*):)**)-#(2#&+#"(>%)","*,-!=#E#'&*(3560&*04#'2'60&*#&''035&(32"#2:#(%)#')&H -)()5(2*#3+#3"#(%)#-)+3<"#2:#-)12-60&(2*#:2*#&1'03(6-)?12-60&()-#BEmD#+3<"&0+=#I)#+%&00 "2(#-3+56++#(%3+#&''035&(32"#:6*(%)*#%)*)=#
EXERCISES 4.22# R)*3;)#(%)#)A'*)++32"+#3"#@C+=#BP=OOD8#BP=OPD8#&"-#BP=OZD= 4.23# $2"+3-)*# *3-<)?*)5(3:3)*#53*563(#/3(%#:30()*#5&'&53(2*#8#'0&5)-#&5*2++#(%)#02&-#*)+3+(2*#,#:2*#(%)#5&+) 3"#/%35%#(%)#(*&"+:2*1)*#+)52"-&*4#-)03;)*+#+3"6+23-#2:#,.#T#B*1+D#%&;3"<#`S?>M#:*)C6)"54#&"-
206 Chapter 4 Diodes &++613"<#@+#=#S=^#T &"-#&-#*)+3+(&"5)#,#=#,SS#Ω=#L3"-#(%)#;&06)#2:#8#(%&(#*)+60(+#3"#*3''0) ;20(&<)#"2#0&*<)*#(%&"#,#T#')&H?(2?')&H=#I%&(#3+#(%)#-5#;20(&<)#&(#(%)#26('6(i#L3"-#(%)#02&-#56**)"(= L3"-#(%)#-32-)+d#52"-65(32"#&"<0)=#l*2;3-)#(%)#&;)*&<)#&"-#')&H#-32-)#56**)"(+#I%&(#3+#(%)#')&H *);)*+)#;20(&<)#&5*2++#)&5%#-32-)i#Y')53:4#(%)#-32-)#3"#()*1+#2:#3(+#')&H#56**)"(#&"-#3(+#l!T= Ans. ,.^,#µL7#,Z=P#T#2*#B )(()*#)+(31&()D#,P=U#T7#S=,Z#E7#S=O`#*&-#B.S=N°D7#,=PZ#E7#.=NP#E7 ,`=. T=#F%6+#+)0)5(#-32-)#/3(%#O=Z?E#(2#P?E#')&H#56**)"(#&"-#.S?T#l!T#*&(3"<=
4.5.5 Precision Half-Wave Rectifier—The Superdiode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v-#<2)+#'2+3(3;)8#(%)#26('6(#;20(&<)#v6#2: (%)#2'#&1'#/300#<2#'2+3(3;)#&"-#(%)#-32-)#/300#52"-65(8#(%6+#)+(&903+%3"<#Ƕ+)-#:))-9&5H '&(%#9)(/))"#(%)#2'#&1'd+#26('6(#()*13"&0#&"-#(%)#")<&(3;)#3"'6(#()*13"&0=#F%3+#")<&(3;)? :))-9&5H#'&(%#/300#5&6+)#3*(6&0#+%2*(#53*563(#(2#&'')&*#9)(/))"#(%)#(/2#3"'6(#()*13"&0+#2:
(a)
(b)
Figure 4.27 F%)# e+6')*-32-)f# '*)53+32"# %&0:?/&;)# *)5(3:3)*# &"-# 3(+# &012+(?3-)&0# (*&"+:)*# 5%&*&5()*3+(35= X2()#(%&(#/%)"#v - > S#&"-#(%)#-32-)#52"-65(+8#(%)#2'#&1'#+6''03)+#(%)#02&-#56**)"(8#&"-#(%)#+26*5)#3+#52";)? "3)"(04#96::)*)-8#&"#&--)-#&-;&"(&<)=#X2(#+%2/"#&*)#(%)#2'?&1'#'2/)*#+6''03)+=
P
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Limiting and Clamping Circuits 207
(%)#2'#&1'=#F%6+#(%)#;20(&<)#&(#(%)#")<&(3;)#3"'6(#()*13"&08#/%35%#3+#&0+2#(%)#26('6(#;20(&<) v. 8#/300#)C6&0#B(2#/3(%3"#:)/#13003;20(+D#(%&(#&(#(%)#'2+3(3;)#3"'6(#()*13"&08#/%35%#3+#(%) 3"'6(#;20(&<)#v- 8 v. = v-
v- ≥ S
X2()#(%&(#(%)#2::+)(#;20(&<)#B!S=N#TD#)A%393()-#3"#(%)#+31'0)#%&0:?/&;)#*)5(3:3)*#53*563(#2: L3<=#P=.,#3+#"2#02"<)*#'*)+)"(=#L2*#(%)#2'?&1'#53*563(#(2#+(&*(#2')*&(32"8#v-#%&+#(2#)A5))-#2"04 ")<03<3904#+1&00#;20(&<)#)C6&0#(2#(%)#-32-)#-*2'#-3;3-)-#94#(%)#2'#&1'd+#2')"?022'#<&3"= !"#2(%)*#/2*-+8#(%)#+(*&3<%(?03")#(*&"+:)*#5%&*&5()*3+(35#v.]v-#&012+(#'&++)+#(%*26<%#(%)#2*3? <3"=#F%3+#1&H)+#(%3+#53*563(#+63(&90)#:2*#&''035&(32"+#3";20;3"<#;)*4#+1&00#+3<"&0+= $2"+3-)*#"2/#(%)#5&+)#/%)"#v-#<2)+#")<&(3;)=#F%)#2'#&1'd+#26('6(#;20(&<)#v6#/300#()"(2#:2002/#&"-#<2#")<&(3;)=#F%3+#/300#*);)*+)?93&+#(%)#-32-)8#&"-#"2#56**)"(#/300#:02/#(%*26<% *)+3+(&"5)#,8#5&6+3"<#v.#(2#*)1&3"#)C6&0#(2#S#T=#F%6+8#:2*#v-#<#S8#v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e+6')*-32-)=f#
EXERCISES 4.24# $2"+3-)*#(%)#-3"!(,'-1(4%!"*,'.'"!#2*#+6')*-32-)#53*563(#2:#L3<=#P=.NB&D8#/3(%#,#=#,#HΩ=#L2*#v-#=#,S 1T8 , T8#&"-#−,#T8#/%&(#&*)#(%)#;20(&<)+#(%&(#*)+60(#&(#(%)#*)5(3:3)*#26('6(#&"-#&(#(%)#26('6(#2:#(%)#2'#&1'i E++61)#(%&(#(%)#2'#&1'#3+#3-)&0#&"-#(%&(#3(+#26('6(#+&(6*&()+#&(#±,.#T=#F%)#-32-)#%&+#S=N?T#-*2'#&( ,?1E#56**)"(= Ans. ,S#1T8#S=ZU#T7#,#T8#,=N#T7#S#T8#−,.#T 4.25# !:#(%)#-32-)#3"#(%)#53*563(#2:#L3<=#P=.NB&D#3+#*);)*+)-8#:3"-#(%)#(*&"+:)*#5%&*&5()*3+(35#v.#&+#:6"5(32"#2:#v-= Ans. v . = S%:2*%v - ≥ S7% v . = v - #:2*%v - ≤ S
4.6 Limiting and Clamping Circuits !"#(%3+#+)5(32"8#/)#+%&00#'*)+)"(#&--3(32"&0#"2"03")&*#53*563(#&''035&(32"+#2:#-32-)+=
4.6.1 Limiter Circuits L3<6*)# P=.^# +%2/+# (%)# <)")*&0# (*&"+:)*# 5%&*&5()*3+(35# 2:# 0313()*# 53*563(=# E+# 3"-35&()-8# :2* 3"'6(+#3"#)*(&3"#*&"<)8# P − ⁄ H ≤ v - ≤ P + ⁄ H 8#(%)#0313()*#&5(+#&+#")&*#53*563(8#'*2;3-3"<#&" 26('6(#'*2'2*(32"&0#(2#(%)#3"'6(8#v.#=#Hv-=#E0(%26<%#3"#<)")*&0#H#5&"#9)#<*)&()*#(%&"#,8#(%)#53*? 563(+#-3+56++)-#3"#(%3+#+)5(32"#%&;)#H#≤#,#&"-#&*)#H"2/"#&+#3($$'#"%4'=',"!$=#B@A&1'0)+#2: &5(3;)#0313()*+#/300#9)#'*)+)"()-#3"#$%&'()*#,N=D#!:#v-#)A5))-+#(%)#6'')*#4:'3?:&<*# ( P + ⁄ H ) 8#(%) 26('6(#;20(&<)#3+#
208 Chapter 4 Diodes
Figure 4.28 k)")*&0# (*&"+:)*# 5%&*&5()*3+(35 :2*#Ĺ()*#53*563(=
Figure 4.29 E''043"<#+3")#/&;)#(2#Ĺ()*#5&"#*)+60(#3"#503''3"<#2::#3(+#(/2#')&H+=
*)-65)-# 9)02/#(%)# 02/)*# 0313(3"<# (%*)+%20-# ( P − ⁄ H )8# (%)# 26('6(# ;20(&<)#v.# 3+# 0313()-#(2# (%) 02/)*#0313(3"<#0);)0# P − = F%)# <)")*&0# (*&"+:)*# 5%&*&5()*3+(35# 2:# L3<=# P=.^# -)+5*39)+# )-+&4"% 4'=',"!W(%&(# 3+8# & 0313()*#(%&(#/2*H+#2"#92(%#(%)#'2+3(3;)#&"-#")<&(3;)#')&H+#2:#&"#3"'6(#/&;):2*1=#E'174"%4'=0 ',"!$8#2:#526*+)8#)A3+(=#L3"&0048#"2()#(%&(#3:#&"#3"'6(#/&;):2*1#+65%#&+#(%&(#+%2/"#3"#L3<=#P=.U 3+#:)-#(2#-2690)#0313()*8#3(+#(/2#')&H+#/300#9)#/
Limiting and Clamping Circuits 209
Figure 4.30 Y2:(#0313(3"<=
Figure 4.31 E#;&*3)(4#2:#9&+35#0313(3"<#53*563(+=
F%)#53*563(#3"#L3<=#P=O,B&D#3+#(%&(#2:#(%)#%&0:?/&;)#*)5(3:3)*#)A5)'(#(%&(#%)*)#(%)#26('6(#3+ (&H)"#&5*2++#(%)#-32-)=#L2*#v-#c#S=Z#T8#(%)#-32-)#3+#56(#2::8#"2#56**)"(#:02/+8#&"-#(%)#;20(&<) -*2'#&5*2++#,#3+#M)*27#(%6+#v.#=#v- =#E+#v-#)A5))-+#S=Z#T8#(%)#-32-)#(6*"+#2"8#);)"(6&004#0313(3"<
210 Chapter 4 Diodes v.# (2# 2")# -32-)# -*2'# BS=N# TD=# F%)# 53*563(# 2:# L3<=# P=O,B9D# 3+# +3130&*# (2# (%&(# 3"# L3<=# P=O,B&D )A5)'(#(%&(#(%)#-32-)#3+#*);)*+)-= R2690)#0313(3"<#5&"#9)#31'0)1)"()-#94#'0&53"<#(/2#-32-)+#2:#2''2+3()#'20&*3(4#3"#'&*&0? 0)08# &+# +%2/"# 3"# L3<=# P=O,B5D=# >)*)# (%)# 03")&*# *)<32"# 2:# (%)# 5%&*&5()*3+(35# 3+# 29(&3")-# :2* ! S=Z#T ≤ v - ≤ S=Z#T=#L2*#(%3+#*&"<)#2:#v-8#92(%#-32-)+#&*)#2::#&"-#v.#=#v- =#E+#v-#)A5))-+#S=Z#T8 +,#(6*"+#2"#&"-#);)"(6&004#0313(+#v.#(2#+ S=N#T=#Y3130&*048#&+#v-#<2)+#12*)#")<&(3;)#(%&"#]S=Z#T8 +.#(6*"+#2"#&"-#);)"(6&004#0313(+#v.#(2#]S=N#T= F%)#(%*)+%20-+#&"-#+&(6*&(32"#0);)0+#2:#-32-)#0313()*+#5&"#9)#52"(*200)-#94#6+3"<#+(*3"<+ 2:#-32-)+#&"-a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m2*)# :0)A390)# 0313()*# 53*563(+# &*)# '2++390)# 3:# 2'# &1'+# &*)# 52193")-# /3(%# -32-)+# &"*)+3+(2*+=#@A&1'0)+#2:#+65%#53*563(+#&*)#-3+56++)-#3"#$%&'()*#,N=
EXERCISE 4.26# E++613"<#(%)#-32-)+#(2#9)#3-)&08#-)+5*39)#(%)#(*&"+:)*#5%&*&5()*3+(35#2:#(%)#53*563(#+%2/"#3"#L3<=#@P=.`=
"
!
Figure E4.26
Ans. v . = v #############:2*# ! Z ≤ v - ≤ +Z v . = ??,.? v - ! .=Z :2*# v - ≤ ! Z v . = ??,.? v - + .=Z :2*# v - ≥ +Z
4.6.2 The Clamped Capacitor or DC Restorer !:#3"#(%)#9&+35#')&H?*)5(3:3)*#53*563(8#(%)#26('6(#3+#(&H)"#&5*2++#(%)#-32-)#*&(%)*#(%&"#&5*2++ (%)#5&'&53(2*8#&"#3"()*)+(3"<#53*563(#/3(%#31'2*(&"(#&''035&(32"+#*)+60(+=#F%)#53*563(8#5&00)-#& -5#*)+(2*)*8#3+#+%2/"#3"#L3<=#P=O.#:)-#/3(%#+C6&*)#/&;)=#_)5&6+)#2:#(%)#'20&*3(4#3"#/%35% (%)#-32-)#3+#52"")5()-8#(%)#5&'&53(2*#/300#5%&*<)#(2#20(&<)#v8#/3(%#(%)#'20&*3(4#3"-35&()-#3" L3<=#P=O.#&"-#)C6&0#(2#(%)#1&<"3(6-)#2:#(%)#12+(#")<&(3;)#')&H#2:#(%)#3"'6(#+3<"&0=#Y69+)? C6)"(048#(%)#-32-)#(6*"+#2::#&"-#(%)#5&'&53(2*#*)(&3"+#3(+#;20(&<)#3"-):3"3()04=#!:8#:2*#3"+(&"5)8 (%)#3"'6(#+C6&*)#/&;)#%&+#(%)#&*93(*&*4#0);)0+#−`#T#&"-#+P#T8#(%)"#v8#/300#9)#)C6&0#(2#`#T= X2/8#+3"5)#(%)#26('6(#;20(&<)#v.#3+#<3;)"#94# v. = v- + v8 3(# :2002/+# (%&(# (%)# 26('6(# /&;):2*1# /300#9)# 3-)"(35&0# (2# (%&(# 2:# (%)# 3"'6(8# )A5)'(# (%&(# 3(# 3+ +%3:()-#6'/&*-#94#v8#;20(+=#!"#26*#)A&1'0)#(%)#26('6(#/300#(%6+#9)#+C6&*)#/&;)#/3(%#0);)0+ 2:#S T#&"-#+,S#T=
Limiting and Clamping Circuits 211
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E"2(%)*#/&4#2:#;3+6&03M3"<#(%)#2')*&(32"#2:#(%)#53*563(#3"#L3<=#P=O.#3+#(2#"2()#(%&( 9)5&6+)#(%)#-32-)#3+#52"")5()-#&5*2++#(%)#26('6(#/3(%#(%)#'20&*3(4#+%2/"8#3(#'*);)"(+#(%) 26('6(#;20(&<)#:*21#<23"<#9)02/#S#T#B94#52"-65(3"<#&"-#5%&*<3"<#6'#(%)#5&'&53(2*8#(%6+ 5&6+3"<# (%)# 26('6(# (2# *3+)# (2# S# TD8# 96(# (%3+# 52"")5(32"# /300# "2(# 52"+(*&3"# (%)# '2+3(3;) )A56*+32"# 2:# v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−S=Z#TD=#F%)"8#&+#(%)#3"'6(#*3+)+#94#@)#;20(+#B&(#4.D8 (%)#26('6(#:2002/+8#&"-#(%)#5450)#*)')&(+#3(+)0:=#!"#(%)#+()&-4#+(&()#(%)#5%&*<)#02+(#94#(%)#5&'&5? 3(2*# -6*3"<# (%)# 3"()*;&0# 4S# (2# 4,# 3+# *)52;)*)-# -6*3"<# (%)# 3"()*;&0# 4,# (2# 4.=# F%3+# 5%&*<) )C63039*361#)"&90)+#6+#(2#5&0560&()#(%)#&;)*&<)#-32-)#56**)"(#&+#/)00#&+#(%)#-)(&30+#2:#(%) 26('6(#/&;):2*1=
Z F%)#-6(4#5450)#2:#'60+)#/&;):2*1#3+#(%)#'*2'2*(32"#2:#)&5%#5450)#2556'3)-#94#(%)#'60+)=#!"#2(%)* /2*-+8#3(#3+#(%)#'60+)#/3-(%#)A'*)++)-#&+#:*&5(32"#2:#(%)#'60+)#')*32-=
212 Chapter 4 Diodes
(b)
(a) (c) Figure 4.33 F%)#50&1')-#5&'&53(2*#/3(%#&-#*)+3+(&"5)#,=
4.6.3 The Voltage Doubler L3<6*)#P=OPB&D#+%2/+#5*563(#521'2+)-#2:#(/2#+)5(32"+#3"#5&+5&-)Q#2&1')-#5&'&53(2* :2*1)-# 94# 8,# &"-# +,8# &"-# ')&H# *)5(3:3)*# :2*1)-# 94# +.# &"-# 8.=# I%)"# )A53()-# 94# &
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4.7 Special Diode Types
!"#$!%"&'%(')*+,"-$&.'!"'-/.'0,)*+"#1'!.0-"%#'+2%3"&.!'-/.'3%,-)1.'4)3.(%2*'!/%4#5 )!!$*"#1'"&.),'&"%&.!5'"#'6"17'8798:;<7'=%-.'-/)-'4/",.'-/.'+%!"-"3.'+.)>!')2.'0,)*+.& -%' ?' @5' -/.' #.1)-"3.' +.)>' 2.)0/.!' −A!"7' B#' 2.!+%#!.' -%' -/"!' 4)3.(%2*5' -/.' +.)>C &.-.0-%2'!.0-"%#'+2%3"&.!')02%!!'0)+)0"-%2'#A')'#.1)-"3.'&0'3%,-)1.'%('*)1#"-$&.'A!"7 D.0)$!.'-/.'%$-+$-'3%,-)1.'"!'&%$;,.'-/.'"#+$-'+.)>5'-/.'0"20$"-'"!'>#%4#')!')'3%,-)1. &%$;,.27'E/.'-.0/#"F$.'0)#';.'.G-.#&.&'-%'+2%3"&.'%$-+$-'&0'3%,-)1.!'-/)-')2.'/"1/.2 *$,-"+,.!'%('!"7
EXERCISE 4.27 B('-/.'&"%&.'"#'-/.'0"20$"-'%('6"17'879A'"!'2.3.2!.&5'4/)-'4",,'-/.'&0'0%*+%#.#-'%('v%';.0%*.U Ans.!−!"#
4.7 Special Diode Types B#'-/"!'!.0-"%#5'4.'&"!0$!!';2".(,H'!%*.'"*+%2-)#-'!+.0"),'-H+.!'%('&"%&.!7
4.7.1 The Schottky-Barrier Diode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
N+)2-' (2%*' R)N!' 0"20$"-!5' I0/%-->H' &"%&.!' ("#&' )++,"0)-"%#' "#' -/.' &.!"1#' %(' )' !+.0"), (%2*'%(';"+%,)2C-2)#!"!-%2',%1"0'0"20$"-!5'>#%4#')!'I0/%-->HCEET5'4/.2.'EET'!-)#&!'(%2 -2)#!"!-%2C-2)#!"!-%2',%1"07 D.(%2.',.)3"#1'-/.'!$;L.0-'%('I0/%-->HC;)22".2'&"%&.!5'"-'"!'"*+%2-)#-'-%'#%-.'-/)-'#%.3.2H'*.-),K!.*"0%#&$0-%2'0%#-)0-'"!')'&"%&.7'B#'()0-5'*.-),'"!'0%**%#,H'&.+%!"-.&'%# P'
E/.'&"!0')00%*+)#H"#1'-/"!'-.G-'0%#-)"#'*)-.2"),'%#'R)N!'0"20$"-!7
213
214 Chapter 4 Diodes (%)#+)1352"-65(2*#+6*:&5)#3"#2*-)*#(2#1&H)#()*13"&0+#:2*#(%)#+)1352"-65(2*#-);35)+#&"-#(2 52"")5(# -3::)*)"(# -);35)+# 3"# &"# 3"()<*&()-?53*563(# 5%3'=# Y65%# 1)(&0]+)1352"-65(2*# 52"(&5(+ &*)#H"2/"#&+#-2='*%*-1,(*,$#(2#-3+(3"<63+%#(%)1#:*21#(%)#*)5(3:43"<#52"(&5(+#(%&(#*)+60(#3" Y_R+=#K%135#52"(&5(+#&*)#6+6&004#1&-)#94#-)'2+3(3"<#1)(&0#2"#;)*4#%)&;304#-2')-#B&"-#(%6+ 02/?*)+3+(3;3(4D#+)1352"-65(2*#*)<32"+=#B[)5&00#(%&(#Y_R+#6+)#12-)*&()04#-2')-#1&()*3&0=D
4.7.2 Varactors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
4.7.3 Photodiodes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l%2(2-32-)+# &*)# 6+6&004# :&9*35&()-# 6+3"<# 521'26"-# +)1352"-65(2*N +65%# &+# <&00361 &*+)"3-)=#F%)#'%2(2-32-)#3+#&"#31'2*(&"(#521'2")"(#2:#<*2/3"<#:&1304#2:#53*563(+#H"2/" &+#-3,-"4"*,!-1'*$#2*#32-,-1'*$=#E+#(%)#"&1)#31'03)+8#+65%#53*563(+#6(303M)#&"#2'(3161#521? 93"&(32"#2:#)0)5(*2"35+#&"-#2'(35+#:2*#+3<"&0#'*25)++3"<8#+(2*&<)8#&"-#(*&"+13++32"=#h+6&0048 )0)5(*2"35+# 3+# (%)# '*):)**)-# 1)&"+# :2*# +3<"&0# '*25)++3"<8# /%)*)&+# 2'(35+# 3+# 12+(# +63()-# :2* (*&"+13++32"#&"-#+(2*&<)=#@A&1'0)+#3"506-)#:39)*?2'(35#(*&"+13++32"#2:#()0)'%2")#&"-#()0);3? +32"#+3<"&0+#&"-#(%)#6+)#2:#2'(35&0#+(2*&<)#3"#$R?[Km#521'6()*#-3+H+=#K'(35&0#(*&"+13++32" '*2;3-)+# ;)*4# /3-)# 9&"-/3-(%+# &"-# 02/# +3<"&0# &(()"6&(32"=# K'(35&0# +(2*&<)# &002/+# ;&+( &126"(+#2:#-&((2#9)#+(2*)-#*)03&904#3"#+1&00#+'&5)= L3"&0048#/)#+%260-#"2()#(%&(#/3(%26(#*);)*+)#93&+8#(%)#300613"&()-#'%2(2-32-)#:6"5(32"+ &+#$-4(!%*"44=#h+6&004#:&9*35&()-#:*21#02/?52+(#+30352"8#+20&*#5)00#52";)*(+#03<%(#(2#)0)5(*3? 5&0#)")*<4=
4.7.4 Light-Emitting Diodes (LEDs) F%)#03<%(?)13((3"<#-32-)#BV@RD#')*:2*1+#(%)#3";)*+)#2:#(%)#:6"5(32"#2:#(%)#'%2(2-32-)7#3( 52";)*(+#:2*/&*-#56**)"(#3"(2#03<%(=#F%)#*)&-)*#/300#*)5&00#:*21#$%&'()*#O#(%&(#3"#:2*/&*-? 93&+)-##$#J6"5(32"8#13"2*3(4#5&**3)*+#&*)#3"J)5()-#&5*2++#(%)#J6"5(32"#&"-#-3::6+)#3"(2#(%)## N
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4.7 Special Diode Types 215
&"-# $# *)<32"+=# F%)# -3::6+3"<# 13"2*3(4# 5&**3)*+# (%)"# *)52193")# /3(%# (%)# 1&J2*3(4# 5&**3)*+= Y65%#*)52193"&(32"#5&"#9)#1&-)#(2#<3;)#*3+)#(2#03<%(#)13++32"=#F%3+#5&"#9)#-2")#94#:&9*35&(? 3"<#(%)##$#J6"5(32"#6+3"<#+)1352"-65(2*#2:#(%)#(4')#H"2/"#&+#-3*)5(?9&"-<&'#1&()*3&0+= k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h+)#2:#(%)#2'(23+20&(2*#'*2;3-)+#521'0)()#)0)5(*35&0#3+20&(32"#9)(/))"#(%)#)0)5? (*35&0#53*563(#(%&(#3+#52"")5()-#(2#(%)#3+20&(2*d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_)42"-#)*(&3"#;&06)#2:#*);)*+)#;20(&<)#B(%&(#-)')"-+ 2"#(%)#-32-)D8#9*)&H-2/"#2556*+8#&"-#56**)"(#3"5*)&+)+ *&'3-04#/3(%#+1&00#52**)+'2"-3"<#3"5*)&+)#3"#;20(&<)= R32-)+#-)+3<")-#(2#2')*&()#3"#(%)#9*)&H-2/"#*)<32"#&*) 5&00)-#M)")*#-32-)+=#F%)4#&*)#)1'024)-#3"#(%)#-)+3<"#2: ;20(&<)# *)<60&(2*+# /%2+)# :6"5(32"# 3+# (2# '*2;3-)# 52"? +(&"(#-5#;20(&<)#(%&(#;&*3)+#03((0)#/3(%#;&*3&(32"+#3"#'2/)* +6''04#;20(&<)#&"-a2*#02&-#56**)"(= !"#1&"4#&''035&(32"+8#4"-65(3"<#-32-)#3+#12-)0)-#&+ %&;3"<# 52"+(&"(# ;20(&<)# -*2'8# 6+6&004# &''*2A31&()04 S=N T= E#-32-)#93&+)-#(2#2')*&()#&(#-5#56**)"(#-+#%&+#+1&00? +3<"&0#*)+3+(&"5)# ' * = @ I ⁄ - + = [)5(3:3)*+# 52";)*(# &5# ;20(&<)+# 3"(2# 6"3'20&*# ;20(&<)+= >&0:?/&;)#*)5(3:3)*+#-2#(%3+#94#'&++3"<#(%)#;20(&<)#3"#%&0: 2:#)&5%#5450)#&"-#9025H3"<#(%)#2''2+3()?'20&*3(4#;20(&<) 3"# (%)# 2(%)*# %&0:# 2:# (%)# 5450)=# L600?/&;)# *)5(3:3)*+
216 Chapter 4 Diodes &5521'03+%#(%)#(&+H#94#'&++3"<#(%)#;20(&<)#3"#%&0:#2:#)&5% 5450)#&"-#3";)*(3"<#(%)#;20(&<)#3"#(%)#2(%)*#%&0:?5450)=
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PROBLEMS Computer Simulation Problems
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CHAPTER 4 P R O B L E M S
&"-#(%6+#2')*&()#(%)#-32-)#&(#.S#1E=#L2*#(%)#+)52"-#-)+3<"8 &++61)# (%&(# (%)# 56**)"(# :*21# (%)# *&/# +6''04# 3+# 0313()-8# &"(%)*):2*)#426#&*)#:2*5)-#(2#2')*&()#(%)#-32-)#&(#S=.Z#1E=#L2* (%)#'6*'2+)#2:#(%)+)#3"3(3&0#-)+3<"+8#&++61)#"2#02&-=#L2*#)&5% -)+3<"#:3"-#(%)#;&06)#2:#,#&"-#(%)#03")#*)<60&(32"=
CHAPTER 4 P R O B L E M S
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CHAPTER 4 P R O B L E M S
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Problems 229
CHAPTER 4 P R O B L E M S
(a)
(e) Figure P4.95
(b)
(f)
(c)
(g)
(d)
(h)
CHAPTER 5
MOS Field-Effect Transistors (MOSFETs) Introduction 5.1
5.6 Basic MOSFET Amplifier Configurations 291
231
Device Structure and Physical Operation 232
5.2 Current—Voltage Characteristics 5.3 MOSFET Circuits at DC
258
5.4 Applying the MOSFET in Amplifier Design 268 5.5 Small-Signal Operation and Models 276
5.7 Biasing in MOS Amplifier Circuits 247
5.8 Discrete-Circuit MOS Amplifiers 5.9 The Body Effect and Other Topics Summary
328
Problems
329
306 314 323
IN THIS CHAPTER YOU WILL LEARN 1. The physical structure of the MOS transistor and how it works. 2. How the voltage between two terminals of the transistor controls the current that flows through the third terminal, and the equations that describe these current–voltage characteristics. 3. How to analyze and design circuits that contain MOS transistors, resistors, and dc sources. 4. How the transistor can be used to make an amplifier, and how it can be used as a switch in digital circuits. 5. How to obtain linear amplification from the fundamentally nonlinear MOS transistor. 6. The three basic ways for connecting a MOSFET to construct amplifiers with different properties. 7. Practical circuits for MOS–transistor amplifiers that can be constructed using discrete components.
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231
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5.1 Device Structure and Physical Operation
S Metal G W D Oxide (SiO2 ) Source region
n!
L
p-type substrate (Body)
n! Channel region B Drain region (a)
Source (S)
Gate (G)
Oxide (SiO2) (thickness " tox)
n!
Drain (D) Metal
Channel region
n!
L p-type substrate (Body)
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233
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5.1 Device Structure and Physical Operation
Gate electrode
! vGS # G
S Oxide (SiO2 )
n!
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D
n!
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Voltage
VGS Vt
vGD (VOV # 21 vDS)
VOV Source 0
% VOV
vDS
Voltage drop along the channel
L 2
Average = 21 vDS
L Drain
x
(a)
%(VOV # vDS)
Channel
Drain
Source (b)
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5.1 Device Structure and Physical Operation
iD
Triode (vDS ! VOV) Curve bends because the channel resistance increases with vDS
Saturation (vDS & VOV) Current saturates because the channel is pinched off at the drain end, and vDS no longer affects the channel.
Almost a straight line with slope proportional to VOV
vGS = Vt + VOV
0
VDS sat " VOV
vDS
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241
242 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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VGS vGD = Vt
Vt 1 2
VOV vDS = VOV
VOV Source 0
Source
L 2 Voltage drop along the channel (a)
Channel
Average = 12 VOV
L Drain
x
Drain (b)
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5.1 Device Structure and Physical Operation
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Solution
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E"K
Q
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Q
= bWZ × @Z ( µ3 cS⋅( ) × b8CQ × @Z 'N
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Q
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243
244 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
Example 5.1 continued
9-*(1
8 *) = 8 # ' ( '8 :8 ' & @8ZQ 'S
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9-*(
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2-$/-';$,7+(
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9-*(1
8 *) = @8QQ'S
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5.1 Device Structure and Physical Operation
S
G
D
p+
p+ n-type substrate
B (a) ! vGS S
#
G iG = 0
iD
iD
p+
iD
D
! vDS #
p+
induced p channel n-type substrate
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%$245
246 Chapter 5 MOS Field-Effect Transistors (MOSFETs) 2-,6,'µ"'$(')-,'304$7$);'0:')-,'-07,('$%')-,'$%+*/,+'"'/-"%%,78'9;<$/"77;1 µ"'e'Z8QW'µ!')0'Z8W µ!0 "%+' $(' <60/,((' ),/-%070&;' +,<,%+,%)8' 9-,' )6"%($()06' )6"%(/0%+*/)"%/,' <"6"3,),6' > "' $( 04)"$%,+'4;'3*7)$<7;$%&'>′"'4;')-,'"(<,/)'6")$0''c&1' > " & >′" ( ' ⁄ & )
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5.1.8 Complementary MOS or CMOS A(')-,'%"3,'$3<7$,(1'/03<7,3,%)"6;'FGH'),/-%070&;',3<70;('FGH')6"%($()06('0:'40)<07"6$)$,(8' A7)-0*&-' ?FGH' /$6/*$)(' "6,' (03,2-")' 306,' +$::$/*7)' )0' :"46$/"),' )-"% `FGH1')-,'"#"$7"4$7$);'0:'/03<7,3,%)"6;'+,#$/,('3"P,('<0(($47,'3"%;'<02,6:*7'/$6/*$)'/0%5 :$&*6")$0%(8'=%+,,+1'")')-,'<6,(,%)')$3,'?FGH'$(')-,'30()'2$+,7;'*(,+'0:'"77')-,'=?'),/-5 %070&$,(8' 9-$(' ()"),3,%)' "<<7$,(' )0' 40)-' "%"70&' "%+' +$&$)"7' /$6/*$)(8' ?FGH' ),/-%070&; -"('#$6)*"77;'6,<7"/,+'+,($&%('4"(,+'0%'`FGH')6"%($()06('"70%,8'I*6)-,6306,1'4;'QZZ[ ?FGH'),/-%070&;'-"+')"P,%'0#,6' 3"%;'"<<7$/")$0%(')-")'.*()'"':,2';,"6(',"67$,6'2,6, <0(($47,' 0%7;' 2$)-' 4$<07"6' +,#$/,(8' 9-60*&-0*)' )-$(' 400P1' 2,' 2$77' ()*+;' 3"%;' ?FGH /$6/*$)'),/-%$O*,(8 I$&*6,' W8@Z' (-02(' "' /60((' (,/)$0%' 0:' "' ?FGH' /-$<' $77*()6")$%&' -02' )-,' _FGH' "%+ `FGH' )6"%($()06(' "6,' :"46$/"),+8' G4(,6#,' )-")' 2-$7,' )-,' `FGH' )6"%($()06' $(' $3<7,3,%),+ +$6,/)7;' $%' )-,' "5);<,' (*4()6"),1' )-,' _FGH' )6"%($()06' $(' :"46$/"),+' $%' "' (<,/$"77;' /6,"),+' ! 6,&$0%1'P%02%'"('"%'!'D&..8'9-,')20'+,#$/,('"6,'$(07"),+':603',"/-'0)-,6'4;'"')-$/P'6,&$0%'0: 0B$+,')-")':*%/)$0%('"('"%'$%(*7")068'`0)'(-02%'0%')-,'+$"&6"3'"6,')-,'/0%%,/)$0%('3"+,')0 )-,'"5);<,'40+;'"%+')0')-,'!'2,778'9-,'7")),6'/0%%,/)$0%'(,6#,('"(')-,'40+;'),63$%"7':06')-, _FGH')6"%($()068
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5.2 Current–Voltage Characteristics
NMOS S SiO2
PMOS D
G
Gate oxide
D
G
S
Polysilicon Thick SiO2 (isolation) n!
n!
SiO2 p!
p! n well
p-type body
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5.2.1 Circuit Symbol I$&*6,' W8@@E"K' (-02(' )-,' /$6/*$)' (;3407' :06' )-,' !5/-"%%,7' ,%-"%/,3,%)5);<,' FGHIJ98 G4(,6#,')-")')-,'(<"/$%&'4,)2,,%')-,')20'#,6)$/"7'7$%,(')-")'6,<6,(,%)')-,'&"),'"%+')-,'/-"%5 %,7'$%+$/"),(')-,':"/)')-")')-,'&"),',7,/)60+,'$('$%(*7"),+':603')-,'40+;'0:')-,'+,#$/,8'9-, <07"6$);'0:')-,'"5);<,'(*4()6"),'E40+;K'"%+')-,'!'/-"%%,7'$('$%+$/"),+'4;')-,'"6602-,"+'0%')-, D
D
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247
248 Chapter 5 MOS Field-Effect Transistors (MOSFETs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a' #B/0 ,62+!0 +10 23C241 "$1+#+5/06/32#+5/0#$0#B/01$-6./0+!02!0!D.B2!!/30E=98 =%'"<<7$/")$0%('2-,6,')-,'(0*6/,'$('/0%%,/),+')0')-,'40+;'0:')-,'+,#$/,1'"':*6)-,6'($3<7$:$/"5 )$0%'0:')-,'/$6/*$)'(;3407'$('<0(($47,1'"('$%+$/"),+'$%'I$&8'W8@@E/K8'9-$('(;3407'$('"7(0'*(,+'$%'"<<7$5 /")$0%('2-,%')-,',::,/)'0:')-,'40+;'0%'/$6/*$)'0<,6")$0%'$('%0)'$3<06)"%)1'"('2$77'4,'(,,%'7"),68
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5.2 Current–Voltage Characteristics
Table 5.1 Regions of Operation of the Enhancement NMOS Transistor
iD +
vGD
−
+
iD
Saturation vDS ≥ vOV
( ) v 2OV
vDS
+
Triode vDS < vOV
1 ) W k 2 n L
vGS = Vtn + vOV
vGS −
−
Cut-off vGS < Vtn
Slope = gDS = r1 DS
0 v = kn) ( W L ) OV
vOV
vDS
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v *( > 8 #!
v *( * 8 #!
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06',O*$#"7,%)7;D
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v () ' v :8
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VOV
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249
250 Chapter 5 MOS Field-Effect Transistors (MOSFETs) iD 1 2
kn) ( WL ) VO2V4
vDS $ vOV Triode region
vDS " vOV Saturation region vGS = V t + VOV4 vDS = vOV 2 iD = 12 kn ( WL ) vDS
1 2
kn) ( WL ) VO2V3
vGS = Vt + VOV3
1 2
kn) ( WL ) VO2V2
vGS = V t + VOV2
1 2
kn) ( WL ) VO2V1
vGS = V t + VOV1 0 VOV1 VOV2 VOV3 VOV4
vGS $ Vt (Cutoff)
vDS
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251
252 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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253
254 Chapter 5 MOS Field-Effect Transistors (MOSFETs) Source
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2-,6,' λ ' "%+' 8 G' E)-,' J"67;' #07)"&,' :06' )-,' _FGH' )6"%($()06K' "6,' 4;' /0%#,%)$0%' %,&")$#, O*"%)$)$,(1'-,%/,'2,'*(,' λ '"%+' 8 G 8 I$%"77;1'2,'(-0*7+'%0),')-")':06'"'&$#,%'?FGH':"46$/")$0%'<60/,(('λ !'"%+' λ " '"6,'&,%,65 "77;'%0)',O*"71'"%+'($3$7"67;':06'8 G!'"%+' 8 G" 8 90'6,/"<1')0')*6%'"'_FGH')6"%($()06'0%1')-,'&"),'#07)"&,'-"(')0'4,'3"+,'702,6')-"%')-") 0:')-,'(0*6/,'4;'")'7,"()' 8 #" 8'90'0<,6"),'$%')-,')6$0+,'6,&$0%1')-,'+6"$%'#07)"&,'-"(')0',B/,,+ )-")'0:')-,'&"),'4;'")'7,"()' 8 #" a'0)-,62$(,1')-,'_FGH'0<,6"),('$%'(")*6")$0%8'I$%"77;1'I$&8'W8QZ <60#$+,('"'<$/)06$"7'6,<6,(,%)")$0%'0:')-,(,'0<,6")$%&'/0%+$)$0%(8'
Table 5.2 Regions of Operation of the Enhancement PMOS Transistor + −
iD
+
vSG
( ) v 2OV
vDG
iD
+
Saturation vSD ≥ |vOV|
1 ) W k 2 p L
vSD
−
Triode vSD < |vOV|
vSG = |Vtp| + |vOV| Cut-off vSG < |Vtp|
−
Slope = gDS = r1 0
|v OV|
DS
|v | = k p) ( W L ) OV
v SD
v )* < 8 #" D'%0'/-"%%,7a')6"%($()06'$%'/*)50::a' + ( & Z v )* & 8 #" ( v :8 D'"'/-"%%,7'$('$%+*/,+a')6"%($()06'0<,6"),('$%')-,')6$0+,'6,&$0%'06'$%')-,'(")*6")$0%'6,&$0% +,<,%+$%&'0%'2-,)-,6')-,'/-"%%,7'$('/0%)$%*0*('06'<$%/-,+50::'")')-,'+6"$%',%+a
96+$,/0F/7+$!
)2#-62#+$!0F/7+$!
?0%)$%*0*('/-"%%,71'04)"$%,+'4;D
_$%/-,+50::'/-"%%,71'04)"$%,+'4;D
v (* > 8 #"
v (* * 8 #"
06',O*$#"7,%)7;D
06',O*$#"7,%)7;
v )( < v :8
v )( ' v :8
9-,%1
9-,%
' + ( & > "′ 55555 &
@ Q
06',O*$#"7,%)7; +(
Q
( v )* ' 8 #" ) v )( ' 555 v )(
' & > "′ 55555 &
Q @ ' + ( & 555 > "′ 55555 ( v )* ' 8 #" )
Q
&
06',O*$#"7,%)7; v :8
@ ' 555 v )( v )( Q
@ ' + ( & 555 > "′ 55555 v Q:8 Q
&
258 Chapter 5 MOS Field-Effect Transistors (MOSFETs) Voltage
S Threshold
Vtp
G Overdrive voltage
Triode VOV Vtp Saturation
D Figure 5.20 9-,'6,7")$#,'7,#,7('0:')-,'),63$%"7' #07)"&,('0:')-,',%-"%/,3,%)5);<,'_FGH')6"%($(5 )06':06'0<,6")$0%'$%')-,')6$0+,'6,&$0%'"%+'$%')-,' (")*6")$0%'6,&$0%8
EXERCISE Q
5.7' 9-,'_FGH')6"%($()06'(-02%'$%'I$&8'JW8f'-"(' 8 #" = ' @'S1'>′" = NZ'µAc S 1 "%+' ' ⁄ & = @Z8 E"K'I$%+')-,'6"%&,'0:'8*':06'2-$/-')-,')6"%($()06'/0%+*/)(8' E4K'=%'),63('0:08*1':$%+')-,'6"%&,'0:'8(':06'2-$/-')-,')6"%($()06'0<,6"),('$%')-,')6$0+,'6,&$0%8' E/K'=%'),63('0:'8*1':$%+')-,'6"%&,'0:'8(':06'2-$/-')-,')6"%($()06'0<,6"),('$%'(")*6")$0%8' E+K'`,&7,/)$%&'/-"%%,757,%&)-'30+*7")$0%'E$8,81'"((*3$%&'λ'='ZK1':$%+')-,'#"7*,('0: 8:8 '"%+'8*' "%+')-,'/066,(<0%+$%&'6"%&,'0:'8(')0'0<,6"),')-,')6"%($()06'$%')-,'(")*6")$0%'30+,'2$)-'?( ='fW'µA8' E,K'=:'λ'='−Z8ZQ'S−@1':$%+')-,'#"7*,'0:'6$'/066,(<0%+$%&')0')-,'0#,6+6$#,'#07)"&,'+,),63$%,+'$% E+K8'' E:K'I06'λ'='−Z8ZQ'S−@'"%+':06')-,'#"7*,'0:'8:8'+,),63$%,+'$%'E+K1':$%+'?('")'8(0= +C'S'"%+'")'8('='Z Sa -,%/,1'/"7/*7"),')-,'#"7*,'0:')-,'"<<"6,%)'0*)<*)'6,($()"%/,'$%'(")*6")$0%8'?03<"6,')0')-,'#"7*,':0*%+ $% E,K8 !5 V
VG ID VD
Figure E5.7
Ans. E"K'8 * ≤ '+b'Sa'E4K'8 ( ≥ 8 * + @a'E/K'8 ( ≤ 8 * + @a'E+K'Z8W'S1'C8W'S1' ≤ b8W'Sa'E,K'Z8Nf'FΩa E:K fd'µA1'dQ8W'µA1'Z8Nf'FΩ'E("3,K
5.3 MOSFET Circuits at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a')-")'$(1 2,'2$77'"((*3,'λ'='Z8'U,'2$77':$%+'$)'/0%#,%$,%)')0'206P'$%'),63('0:')-,'0#,6+6$#,'#07)"&,a 8:8 '='8*) − 8#!':06'`FGH'"%+' 8 :8 & 8 )* ' 8 #" ':06'_FGH8
5.3 MOSFET Circuits at DC
Example 5.3 ^,($&%')-,'/$6/*$)'0:'I$&8'W8Q@1')-")'$(1'+,),63$%,')-,'#"7*,('0:' F ('"%+' F )1''(0')-")')-,')6"%($()06'0<,6"),( ")'?('='Z8b'3A'"%+'8('='+Z8W'S8'9-,'`FGH')6"%($()06'-"('8#'='Z8f'S1'µ!<$%'='@ZZ'µAcSQ1'&'='@'µ31'"%+ ''='CQ'µ38'`,&7,/)')-,'/-"%%,757,%&)-'30+*7")$0%',::,/)'E$8,81'"((*3,')-")'λ'='ZK8'
VDD " !2.5 V
VSS " #2.5 V
Figure 5.21 ?$6/*$)':06'JB"3<7,'W8C8
Solution 90',()"47$(-'"'+/'#07)"&,'0:'+Z8W'S'")')-,'+6"$%1'2,'3*()'(,7,/)'F('"(':07702(D 8 (( ' 8 ( 5 F ( = 5555555555555555555555 ?( Q8W ' Z8W = 555555555555555555555 = W'PΩ Z8b 90'+,),63$%,')-,'#"7*,'6,O*$6,+':06' F ) 1'2,'%,,+')0'P%02')-,'#07)"&,'")')-,'(0*6/,1'2-$/-'/"%'4,',"($7; :0*%+'$:'2,'P%02'8 *)8'9-$('$%')*6%'/"%'4,'+,),63$%,+':603'8 :8 8'902"6+')-")',%+1'2,'%0),')-")'($%/,'8('= Z8W'S'$('&6,"),6')-"%'8* 1')-,'`FGH')6"%($()06'$('0<,6")$%&'$%')-,'(")*6")$0%'6,&$0%1'"%+'2,'/"%'*(,')-,'(")5 *6")$0%56,&$0%',B<6,(($0%'0:'+(')0'+,),63$%,')-,'6,O*$6,+'#"7*,'0:'8:8 1 @ ' Q ? ( = 555 µ ! < $% 55555 8 :8 Q & 9-,%'(*4()$)*)$%&'?('='Z8b'3A'='bZZ'µA1'µ!<$%'='@ZZ'µAcSQ1'"%+ ' ⁄ & = CQ ⁄ @ '&$#,(
2-$/-'6,(*7)('$%' 9-*(1
@ CQ Q bZZ = 555 × @ZZ × 555555 8 :8 Q @ 8 :8 = Z8W'S 8 *) = 8 # + 8 :8 = Z8f + Z8W = @8Q'S
i,:,66$%&')0'I$&8'W8Q@1'2,'%0),')-")')-,'&"),'$('")'&60*%+'<0),%)$"78'9-*(1')-,'(0*6/,'3*()'4,'")'−@8Q'S1'"%+')-, 6,O*$6,+'#"7*,'0:'F)'/"%'4,'+,),63$%,+':603 8 ) ' 8 )) 5 F ) = 5555555555555555555 ?( −@8Q' ' ' ( ' Q8W ) = 5555555555555555555555555555555555 = C8QW'PΩ Z8b
259
260 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
EXERCISE D5.8 i,+,($&%'')-, '/$6/*$)'0:'I$&8'W8Q@':06')-,':07702$%&'/"(,D08(('=' −8))' ='Q8W'S1'8#'='@'S1'µ!<$%'='NZ µAcSQ1'' ' ⁄ & = @QZ'µ3 ⁄ C 'µ31 ?('='Z8C'3A1'"%+'8('='+Z8b'S8 Ans. F('='f'PΩ; F)0= C8C'PΩ
Example 5.4 I$&*6,'W8QQ'(-02('"%'`FGH')6"%($()06'2$)-'$)('+6"$%'"%+'&"),'),63$%"7('/0%%,/),+')0&,)-,68'I$%+')-,' + ' v 6,7")$0%(-$<' 0:' )-,' 6,(*7)$%&' )205),63$%"7' +,#$/,' $%' ),63(' 0:' )-,' FGHIJ9' <"6"3,),6(' > ! & >′! ( ' ⁄ & ) "%+'8 #! 8'`,&7,/)'/-"%%,757,%&)-'30+*7")$0%'E$8,81'λ ' & ZK 8'`0),')-")')-$(')205),63$%"7'+,#$/,'$('P%02%'"('" ')"'&3%"**&%-&'+-$(*!)!-"$8 i
!
v
#
Figure 5.22
Solution H$%/,'v ( & v *'$3<7$,('0<,6")$0%'$%')-,'(")*6")$0%'30+,1' @ ' Q + ( & 555 >′! 55555 ( v *) ' 8 #! ) Q &
`021'+ & + ( '"%+' v & v *) 1')-*(' @ ' Q + & 555 >′! 55555 ( v ' 8 #! ) & Q ' i,<7"/$%&' >′! 55555 '4;'> ! '6,(*7)('$%' & @ Q + & 555 > ! ( v ' 8 #! ) Q
5.3 MOSFET Circuits at DC
EXERCISES D5.9 I06')-,'/$6/*$)'$%'I$&8'JW8[1':$%+')-,'#"7*,'0:'F')-")'6,(*7)('$%' 8 ( & Z8d'S8''9-,'FGHIJ9'-"( Z8fQ'µ3 8 #! & Z8W'S1' µ ! < $% & Z8b '3AcSQ1'' ⁄ & & 555555555555555555555 1'"%+'λ & Z8 Z8@d'µ3 Ans. @C8['PΩ !1.8 V
R VD Q1 Figure E5.9
D5.10 I$&*6,'JW8@Z1'(-02('"'/$6/*$)'04)"$%,+'4;'"*&3,%)$%&')-,'/$6/*$)'0:'I$&8'JW8['/0%($+,6,+'$%'JB,65 /$(,'W8['2$)-'"')6"%($()06'; Q'$+,%)$/"7')0'; @'"%+'"'6,($()"%/,' F Q8'I$%+')-,'#"7*,'0:' F Q')-")'6,(*7)('$% ; Q'0<,6")$%&'")')-,',+&,'0:')-,'(")*6")$0%'6,&$0%8'n(,';0*6'(07*)$0%')0'JB,6/$(,'W8[8 Ans. QZ8d'PΩ VDD!1.8 V R2
R
Q2
Q1 Figure E5.10
Example 5.5 ^,($&%')-,'/$6/*$)'$%'I$&8'W8QC')0',()"47$(-'"'+6"$%'#07)"&,'0:'Z8@'S8'U-")'$(')-,',::,/)$#,'6,($()"%/,'4,)2,,% Q +6"$%'"%+'(0*6/,'")')-$('0<,6")$%&'<0$%)g'T,)'8 #! = @'S'"%+' > !′ ( ' ⁄ & ) = @'3AcS 8 VDD " !5 V ID
RD VD " !0.1 V
Figure 5.23 ?$6/*$)':06'JB"3<7,'W8W8
261
262 Chapter 5 MOS Field-Effect Transistors (MOSFETs) Example 5.5 continued
Solution H$%/,')-,'+6"$%'#07)"&,'$('702,6')-"%')-,'&"),'#07)"&,'4;'b8['S'"%+'8 #! = @'S1')-,'FGHIJ9'$('0<,6")$%& $%')-,')6$0+,'6,&$0%8'9-*(')-,'/*66,%)'?('$('&$#,%'4; @ Q ' ? ( = > !′ 55555 ( 8 *) ' 8 #! )8 () ' 555 8 () Q & @ ? ( = @ × ( W ' @ ) × Z8@ ' 555 × Z8Z@ Q = Z8C[W'3A 9-,'6,O*$6,+'#"7*,':06'F('/"%'4,':0*%+'"(':07702(D 8 (( ' 8 ( 5 F ( = 5555555555555555555555 ?( W ' Z8@ = 5555555555555555 = @Q8b'PΩ Z8C[W =%'"'<6"/)$/"7'+$(/6,),5/$6/*$)'+,($&%'<6047,31'0%,'(,7,/)(')-,'/70(,()'()"%+"6+'#"7*,'"#"$7"47,':061'(";1'Wo 6,($()06(p$%')-$('/"(,1'@Q'PΩa'(,,'A<<,%+$B']8'H$%/,')-,')6"%($()06'$('0<,6")$%&'$%')-,')6$0+,'6,&$0%'2$)-'" (3"77'8()1')-,',::,/)$#,'+6"$%5)05(0*6/,'6,($()"%/,'/"%'4,'+,),63$%,+'"(':07702(D 8 () 5 6 () = 55555555 ?( Z8@ = 5555555555555 = QWC'Ω Z8C[W
EXERCISE 5.11' =:'$%')-,'/$6/*$)'0:'JB"3<7,'W8W')-,'#"7*,'0:'F('$('+0*47,+1':$%+'"<<60B$3"),'#"7*,(':06'?('"%+'8(8 Ans. Z8Q'3Aa'Z8ZW'S
5.3 MOSFET Circuits at DC
Example 5.6 A%"7;>,')-,'/$6/*$)'(-02%'$%'I$&8'W8QbE"K')0'+,),63$%,')-,'#07)"&,('")'"77'%0+,('"%+')-,'/*66,%)(')-60*&"77' 46"%/-,(8' T,)'8 #! = @'S' "%+' > !′ ( ' ⁄ & ) = @'3AcS Q 8' `,&7,/)' )-,' /-"%%,757,%&)-' 30+*7")$0%' ,::,/) E$8,81'"((*3,' λ = ZK8 VDD " !10 V
!10 V 0.5 µA
ID
RD " 6 k( 10 M(
RG1 " 10 M(
6 k( 0
10 # 6 ID
!5 V 6 ID RG2 " 10 M(
RS " 6 k(
10 M(
6 k( ID
(a)
(b)
Figure 5.24 1(2'?$6/*$)':06'JB"3<7,'W8N8'1/2'9-,'/$6/*$)'2$)-'(03,'0:')-,'"%"7;($('+,)"$7('(-02%8
Solution H$%/,')-,'&"),'/*66,%)'$('>,601')-,'#07)"&,'")')-,'&"),'$('($3<7;'+,),63$%,+'4;')-,'#07)"&,'+$#$+,6':063,+ 4;')-,')20'@Z5FΩ'6,($()06(1 F *Q @Z 5 = @Z × 555555555555555555 = +W'S 8 * = 8 (( 55555555555555555555555 @Z + @Z F *Q + F *@ U$)-')-$('<0($)$#,'#07)"&,'")')-,'&"),1')-,'`FGH')6"%($()06'2$77'4,')*6%,+'0%8'U,'+0'%0)'P%021'-02,#,61 2-,)-,6')-,')6"%($()06'2$77'4,'0<,6")$%&'$%')-,'(")*6")$0%'6,&$0%'06'$%')-,')6$0+,'6,&$0%8'U,'(-"77'"((*3, (")*6")$0%56,&$0%'0<,6")$0%1'(07#,')-,'<6047,31'"%+')-,%'/-,/P')-,'#"7$+$);'0:'0*6'"((*3<)$0%8'G4#$0*(7;1 $:' 0*6' "((*3<)$0%' )*6%(' 0*)' %0)' )0' 4,' #"7$+1' 2,' 2$77' -"#,' )0' (07#,' )-,' <6047,3' "&"$%' :06' )6$0+,56,&$0% 0<,6")$0%8 i,:,6' )0' I$&8' W8QbE4K8' H$%/,' )-,' #07)"&,' ")' )-,' &"),' $(' W' S' "%+' )-,' #07)"&,' ")' )-,' (0*6/,' $( ? ( ' ( 3A ) × N' ( PΩ ) = N? ( 1 '2,'-"#, 8 *) = W ' N? ( 9-*(1'?('$('&$#,%'4; @ ' Q ? ( = 555 > !′ 55555 ( 8 *) ' 8 #! ) Q & @ Q = 555 × @ × ( W ' N? ( ' @ ) Q 2-$/-'6,(*7)('$%')-,':07702$%&'O*"+6")$/',O*")$0%'$%'?(D Q
@d? ( ' QW? ( + d = Z
263
264 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
Example 5.6 continued
9-$(',O*")$0%';$,7+(')20'#"7*,(':06'?(D'Z8d['3A'"%+'Z8W'3A8'9-,':$6()'#"7*,'6,(*7)('$%'"'(0*6/,'#07)"&,'0: N × Z8d[ = W8Cb S1 '2-$/-'$('&6,"),6')-"%')-,'&"),'#07)"&,'"%+'+0,('%0)'3"P,'<-;($/"7'(,%(,'"('$)'20*7+ $3<7;')-")')-,'`FGH')6"%($()06'$('/*)'0::8'9-*(1 ? ( = Z8W'3A 8 ) = Z8W × N = +C'S 8 *) = W ' C = Q'S 8 ( = @Z ' N × Z8W = +f'S
H$%/,' 8 ( > 8 * ' 8 #! 1 ')-,')6"%($()06'$('0<,6")$%&'$%'(")*6")$0%1'"('$%$)$"77;'"((*3,+8
EXERCISES 5.12' I06')-,'/$6/*$)'0:'I$&8'W8Qb1'2-")'$(')-,'7"6&,()'#"7*,')-")'F('/"%'-"#,'2-$7,')-,')6"%($()06'6,3"$%( $%')-,'(")*6")$0%'30+,g Ans. @Q'PΩ D5.13' i,+,($&%')-,'/$6/*$)'0:'I$&8'W8Qb':06')-,':07702$%&'6,O*$6,3,%)(D' 8 (( = +W'S1 ? ( = Z8CQ'3A1 8) = @8N S1'8('='C8b'S1'2$)-'"'@5µA'/*66,%)')-60*&-')-,'#07)"&,'+$#$+,6'F*@1'F*Q8'A((*3,')-,'("3, FGHIJ9'"('$%'JB"3<7,'W8N8 Ans. F*@'='@8N'FΩa'F*Q'='C8b'FΩ1'F)'='F('='W'PΩ
Example 5.7 ^,($&%' )-,' /$6/*$)' 0:' I$&8' W8QW' (0' )-")' )-,' )6"%($()06' 0<,6"),(' $%' (")*6")$0%' 2$)-' ? ( = Z8W'3A ' "%+ 8 ( = +C'S8 T,)' )-,' ,%-"%/,3,%)5);<,' _FGH' )6"%($()06' -"#,' 8 #" = ' @'S ' "%+' > "′ ( ' ⁄ & ) = ' @ 3AcSQ8 A((*3,'λ'='Z8'U-")'$(')-,'7"6&,()'#"7*,')-")'F('/"%'-"#,'2-$7,'3"$%)"$%$%&'(")*6")$0%56,&$0%'0<,6")$0%g VDD " !5 V
RG1
VD " !3 V RG2
RD ID " 0.5 mA
Figure 5.25 ?$6/*$)':06'JB"3<7,'W8f8
5.3 MOSFET Circuits at DC
Solution H$%/,')-,'FGHIJ9'$(')0'4,'$%'(")*6")$0%1'2,'/"%'26$), @ ' ? ( & 555 > "′ 55555 8:8 Q &
Q
Q
H*4()$)*)$%&'?('='Z8W'3A'"%+' > "′' ⁄ & = @'3AcS 1'2,'04)"$% 8 :8 = @'S "%+ 8 )* & 8 #" ( 8 :8 & @ ( @ & Q'S H$%/,')-,'(0*6/,'$('")'+W'S1')-,'&"),'#07)"&,'3*()'4,'(,)')0'+C'S8'9-$('/"%'4,'"/-$,#,+'4;')-, "<<60<6$"), (,7,/)$0%'0:')-,'#"7*,('0:'F*@'"%+'F*Q8'A'<0(($47,'(,7,/)$0%'$('F*@'='Q'FΩ'"%+'F*Q'='C'FΩ8 9-,'#"7*,'0:'F('/"%'4,':0*%+':603 8 C F ( = 555555( = 5555555 = N'PΩ ?( Z8W H")*6")$0%530+,'0<,6")$0%'2$77'4,'3"$%)"$%,+'*<')0')-,'<0$%)')-")'8(',B/,,+('8*'4;' 8 #" a )-")'$(1'*%)$7 8 ( 3"B = C + @ = b'S 9-$('#"7*,'0:'+6"$%'#07)"&,'$('04)"$%,+'2$)-'F('&$#,%'4; b F ( = 5555555 = d'PΩ Z8W
EXERCISE D5.14 'I06')-,'/$6/*$)'$%'I$&8'JW8@b1':$%+')-,'#"7*,'0:'F')-")'6,(*7)('$%')-,'_FGH')6"%($()06'0<,6")$%&'2$)"%'0#,6+6$#,'#07)"&,' 8 :8 & Z8N'S8'9-,')-6,(-07+'#07)"&,'$(' 8 #" & ' Z8b'S1')-,'<60/,((')6"%(/0%5 +*/)"%/,'<"6"3,),6'> " ′ & Z8@'3AcSQ1'"%+''c&'e'@Z'µ3cZ8@d'µ38 Ans. dZZ'Ω "1.8 V R
Figure E5.14
265
266 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
Example 5.8 9-,' `FGH' "%+' _FGH' )6"%($()06(' $%' )-,' /$6/*$)' 0:' I$&8' W8QNE"K' "6,' 3")/-,+1' 2$)- > !′ ( ' ! ⁄ & ! ) = Q > "′( ' " ⁄ & " ) = @'3AcS '"%+' 8 #! = ' 8 #" = @'S8 'A((*3$%&' λ = Z ':06'40)-'+,#$/,(1':$%+')-,'+6"$%'/*65 6,%)('+(I'"%+'+(J1'"('2,77'"(')-,'#07)"&,'v: 1':06' v ? = Z'S1 +Q8W'S1'"%+' ' Q8W'S8 !2.5 V
!2.5 V
QP
QP
iDP vI
vO
iDN QN
IDP vO
0V IDN QN
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55@5 Q
Q
× @ × ( Q8W ' @ ) = @8@QW'3A
5.3 MOSFET Circuits at DC
267
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v : = ' Q8bb'S
`0),')-")' 8 () = −Q8bb ' ( ' Q8W ) = Z8ZN'S1 2-$/-'$('(3"77'"('"((*3,+8 I$%"77;1')-,'($)*")$0%':06')-,'/"(,'v ? = ' Q8W'S'qI$&8'W8QNE+Kr'2$77'4,')-,',B"/)'/03<7,3,%)'0:')-,'/"(, v ? = +Q8W'SD' 96"%($()06' ;I' 2$77' 4,' 0::8' 9-*(' ? (I = Z1' ;J' 2$77' 4,' 0<,6")$%&' $%' )-,' )6$0+,' 6,&$0%' 2$)? (J = Q8bb'3A'"%+' v : = +Q8bb'S8
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268 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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A
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EXERCISE 5.16
?0%($+,6')-,'"3<7$:$,6'0:'I$&8'W8QfE"K'2$)-' 8 (( & @8d 'S1' F ( & @f8W 'P Ω1'"%+'2$)-'"'FGHIJ9 (<,/$:$,+')0'-"#,' 8 # & Z8b 'S1' > ! & b'3AcSQ1'"%+'λ & Z8'^,),63$%,')-,'/006+$%"),('0:')-,',%+ <0$%)(' 0:' )-,' (")*6")$0%56,&$0%' (,&3,%)' 0:' )-,' S9?8' A7(01' +,),63$%,' 8 () ' "((*3$%& ? 8 *) & 8 (( 8 ?
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269
270 Chapter 5 MOS Field-Effect Transistors (MOSFETs) vDS VDD
A
VDD ID
RD + VDS
+ VGS
Q
VDS
–
–
B C
(a)
0
Vt
VGS
VDD
vGS
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VDD
iD
RD vDS
vgs VGS
! #
! vGS # (a)
vDS
VDD
A Slope at Q 5 voltage gain vds
VDS
Q
Time
B C Vt
VGS
VDD
vGS
vgs
Time (b)
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271
272 Chapter 5 MOS Field-Effect Transistors (MOSFETs) U,'3"P,')-,':07702$%&'04(,6#")$0%('0%')-$(',B<6,(($0%':06')-,'#07)"&,'&"$%8 1. 9-,'&"$%'$('%,&")$#,1'2-$/-'($&%$:$,(')-")')-,'"3<7$:$,6'$('$%#,6)$%&a')-")'$(1')-,6,'$('" @dZ ° <-"(,'(-$:)'4,)2,,%')-,'$%<*)'"%+')-,'0*)<*)8'9-$('$%#,6($0%'$('04#$0*('$%'I$&8 W8Q[E4K'"%+'(-0*7+'-"#,'4,,%'"%)$/$<"),+':603'JO8'EW8CQK8' 2. 9-,' &"$%' $(' <60<06)$0%"7' )0' )-,' 70"+' 6,($()"%/,' F ( 1' )0' )-,' )6"%($()06' )6"%(/0%+*/5 )"%/,' <"6"3,),6' > ! 1' "%+' )0' )-,' 0#,6+6$#,' #07)"&,' 8 :8 8' 9-$(' "77' 3"P,(' $%)*$)$#, (,%(,8 A%0)-,6' ($3<7,' "%+' $%($&-):*7' ,B<6,(($0%' :06' )-,' #07)"&,' &"$%' G v ' /"%' 4,' +,6$#,+' 4; 6,/"77$%&')-")')-,'+/'/*66,%)'$%')-,'+6"$%'")')-,'4$"('<0$%)'$('6,7"),+')0'8:8 '4; @ Q ? ( & 555 > ! 8 :8 Q
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Example 5.9 ?0%($+,6' )-,' "3<7$:$,6' /$6/*$)' (-02%' $%' I$&8' W8Q[E"K8' 9-,' )6"%($()06' $(' (<,/$:$,+' )0' -"#,' 8 # & Z8b' S1 > !′ & Z8b '3AcSQ1''c&'e'@Z1'"%+' λ & Z 8'A7(01'7,)' 8 (( & @8d 'S1' F ( & @f8W 'P Ω 1'"%+'8 *) & Z8N'S8 E"K'I06' v 71 & Z 'E"%+'-,%/,' v ,1 & Z K1':$%+'8 :8 1' ? (1'8 () 1'"%+' G v8 E4K' U-")' $(' )-,' 3"B$3*3' (;33,)6$/"7' ($&%"7' (2$%&' "7702,+' ")' )-,' +6"$%g' !,%/,' :$%+' )-,' 3"B$3*3 "7702"47,'"3<7$)*+,'0:'"'($%*(0$+"7' v 718
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281
282 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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283
284 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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285
286 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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297
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#07)"&,' ")' )-,' (0*6/,' ),63$%"7' 2$77' :07702' )-")' ")' )-,' $%<*)1' -,%/,' )-,' %"3,' 1$-6./0 M$3D 3$C/68 =%'/0%/7*($0%1')-,'(0*6/,':07702,6':,")*6,('"'#,6;'-$&-'$%<*)'6,($()"%/,'E$+,"77;1'$%:$5 %$),K1'"'6,7")$#,7;'702'0*)<*)'6,($()"%/,1'"%+'"%'0<,%5/$6/*$)'#07)"&,'&"$%')-")'$('%,"6'*%$); E$+,"77;1'*%$);K8'9-*(')-,'(0*6/,':07702,6'$('$+,"77;'(*$),+':06'$3<7,3,%)$%&')-,'*%$);5&"$% #07)"&,' 4*::,6' 0:' I$&8' W8b[E/K8' 9-,' (0*6/,' :07702,6' $(' "7(0' *(,+' "(' )-,' 0*)<*)' E$8,81' 7"()K ()"&,'$%'"'3*7)$()"&,'"3<7$:$,61'2-,6,'$)(':*%/)$0%'$(')0',O*$<')-,'0#,6"77'"3<7$:$,6'2$)-'" 702'0*)<*)'6,($()"%/,1')-*(',%"47$%&'$)')0'(*<<7;'6,7")$#,7;'7"6&,'70"+'/*66,%)('2$)-0*)'70(( 0:' &"$%' E$8,81' 2$)-' 7$))7,' 6,+*/)$0%' 0:' 0*)<*)' ($&%"7' 7,#,7K8' 9-,' +,($&%' 0:' 0*)<*)' ()"&,(' $( ()*+$,+'$%'?-"<),6'@@8
EXERCISES D5.30 =)' $(' 6,O*$6,+' )0' +,($&%' "' (0*6/,' :07702,6' )-")' $3<7,3,%)(' )-,' 4*::,6' "3<7$:$,6' (-02%' $%' I$&8 W8b[E/K8'=:')-,'FGHIJ9'$('0<,6"),+'2$)-'"%'0#,6+6$#,'#07)"&,' 8 :8 & Z8QW'S1'")'2-")'+6"$%'/*65 6,%)'(-0*7+'$)'4,'4$"(,+g'I$%+')-,'0*)<*)'($&%"7'"3<7$)*+,'"%+')-,'($&%"7'"3<7$)*+,'4,)2,,%'&"), "%+'(0*6/,8 Ans. @8QW'3Aa'Z8[@'Sa'[@'3S D5.31 A'FGHIJ9'$('/0%%,/),+'$%')-,'(0*6/,5:07702,6'/0%:$&*6")$0%'"%+',3<70;,+'"(')-,'0*)<*)'()"&, 0:'"'/"(/"+,'"3<7$:$,68'=)'$('6,O*$6,+')0'<60#$+,'"%'0*)<*)'6,($()"%/,'0:'QZZ' Ω 8'=:')-,'FGHIJ9 -"(' >′! & Z8b '3AcSQ'"%+'$('0<,6"),+'")' 8 :8 ' & Z8QW 'S1':$%+')-,'6,O*$6,+''c&'6")$08'A7(0'(<,/$:; )-,'+/'4$"('/*66,%)' ? ( 8 '=:')-,'"3<7$:$,6'70"+'6,($()"%/,'#"6$,('0#,6')-,'6"%&,'@'P Ω ')0'@Z'P Ω1 2-")'$(')-,'6"%&,'0:' * v '0:')-,'(0*6/,':07702,6g Ans. WZa'Z8NQW'3Aa'Z8dC'ScS')0'Z8[d'ScS 5.32 i,:,6')0'I$&8'W8WZE4K8'H-02')-")')"P$%&' 6 $ '$%)0'"//0*%)'6,(*7)('$% 6$ G v$ ' & 55555555555555555555555 5 6$ ( @ ⁄ 7@ `021'6,/"77$%&')-")' 6 $ & 8 G ⁄ ? ( '"%+' 7 @ & Q? ( ⁄ 8 :8 1':$%+' G v$ '$%'),63('0:' 8 G '"%+' 8 :8 8'I06'" ),/-%070&;':06'2-$/-'8 G & QZ 'S1'2-")'$(')-,'3"B$3*3' 8 :8 '")'2-$/-')-,')6"%($()06'/"%'4,'0<,65 "),+'2-$7,'04)"$%$%&' G v$ ≥ Z8[[ 'ScSg Ans.' G v$ & @ ⁄ [ @ ( 8 :8 ⁄ Q8 G ]a'Z8b'S
5.6.7 Summary and Comparisons I06',"(;'6,:,6,%/,'"%+')0',%"47,'/03<"6$(0%(1'2,'<6,(,%)'$%'9"47,'W8b')-,':063*7"(':06'+,),65 3$%$%&' )-,' /-"6"/),6$()$/' <"6"3,),6(' 0:' +$(/6,),' FGH' "3<7$:$,6(8' `0),' )-")' 6 $' -"(' 4,,% %,&7,/),+')-60*&-0*)8'9-$('$('4,/"*(,'0*6'$%),6,()'$%')-$('/-"<),6'$('<6$3"6$7;'$%'+$(/6,),5/$6/*$) "3<7$:$,6(8'A('"76,"+;'3,%)$0%,+1' 6 $'-"('"'6,7")$#,7;'(3"77',::,/)'0%')-,'<,6:063"%/,'0:'+$(5 /6,),5/$6/*$)'"3<7$:$,6('"%+'/"%'*(*"77;'4,'%,&7,/),+8'=%'(03,'/"(,(1'-02,#,61'$)'$('#,6;',"(;')0 )"P,' 6 $'$%)0'"//0*%)1'(*/-'"('$%')-,'/"(,'0:')-,'?H'"%+'?^'"3<7$:$,6(1'"%+'0%,'$(',%/0*6"&,+')0 +0'(08'I06'$%),&6"),+5/$6/*$)'"3<7$:$,6(1'6 $'@-1#0"72";('4,')"P,%'$%)0'"//0*%)8
305
306 Chapter 5 MOS Field-Effect Transistors (MOSFETs) '
Table 5.4 Characteristics of MOSFET Amplifiers 38$+$4-,+'.-'4."1)4 9#:%';',+)-<:, ?0330%'(0*6/, EI$&8'W8bWK
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5.7 Biasing in MOS Amplifier Circuits A('+$(/*((,+'$%'H,/)$0%'W8b1'"%',((,%)$"7'(),<'$%')-,'+,($&%'0:'"'FGHIJ9'"3<7$:$,6'/$6/*$)'$( )-,' ,()"47$(-3,%)' 0:' "%' "<<60<6$"),' +/' 0<,6")$%&' <0$%)' :06' )-,' )6"%($()068' 9-$(' $(' )-,' (),< P%02%'"('4$"($%&'06'4$"('+,($&%8'A%'"<<60<6$"),'+/'0<,6")$%&'<0$%)'06'4$"('<0$%)'$('/-"6"/5 ),6$>,+'4;'"'()"47,'"%+'<6,+$/)"47,'+/'+6"$%'/*66,%)'?('"%+'4;'"'+/'+6"$%5)05(0*6/,'#07)"&,'8() )-")',%(*6,('0<,6")$0%'$%')-,'(")*6")$0%'6,&$0%':06'"77',B<,/),+'$%<*)5($&%"7'7,#,7(8'
5.7 Biasing in MOS Amplifier Circuits
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@ ' Q ? ( = 555 µ ! < $% 55555 ( 8 *) ' 8 # ) Q & "%+' %0),' )-")' )-,' #"7*,(' 0:' )-,' )-6,(-07+' #07)"&,' 8# 1' )-,' 0B$+,5/"<"/$)"%/,' <$% 1' "%+' E)0' " 7,((,6',B),%)K')-,')6"%($()06'"(<,/)'6")$0 ' ⁄ & #"6;'2$+,7;'"30%&'+,#$/,('0:'(*<<0(,+7;')-,'("3, ($>,'"%+');<,8'9-$('$('/,6)"$%7;')-,'/"(,':06'+$(/6,),'+,#$/,(1'$%'2-$/-'7"6&,'(<6,"+('$%')-, #"7*,('0:')-,(,'<"6"3,),6('0//*6'"30%&'+,#$/,('0:')-,'("3,'3"%*:"/)*6,6m('<"6)'%*34,68 9-,'(<6,"+'$('"7(0'7"6&,'$%'$%),&6"),+'/$6/*$)(1',(<,/$"77;'"30%&'+,#$/,(':"46$/"),+'0%'+$::,65 ,%)'2":,6('"%+'/,6)"$%7;'4,)2,,%'+$::,6,%)'4")/-,('0:'2":,6(8'I*6)-,6306,1'40)-'8#'"%+'µ! +,<,%+'0%'),3<,6")*6,1'2$)-')-,'6,(*7)')-")'$:'2,':$B')-,'#"7*,'0:'8*)1')-,'+6"$%'/*66,%)'?( 4,/03,('#,6;'3*/-'),3<,6")*6,'+,<,%+,%)8 90',3<-"($>,')-,'<0$%)')-")'4$"($%&'4;':$B$%&'8*)'$('%0)'"'&00+'),/-%$O*,1'2,'(-02'$% I$&8'W8W@')20'+(Vv*)'/-"6"/),6$()$/'/*6#,('6,<6,(,%)$%&',B)6,3,'#"7*,('$%'"'4")/-'0:'FGHIJ9( 0:')-,'("3,');<,8'G4(,6#,')-")':06')-,':$B,+'#"7*,'0:'8*)1')-,'6,(*7)"%)'(<6,"+'$%')-,'#"7*,('0: )-,'+6"$%'/*66,%)'/"%'4,'(*4()"%)$"78 iD
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307
308 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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VDD VDD
RG1
RD ID
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5.7 Biasing in MOS Amplifier Circuits
309
0<<0($),')0')-")'$%$)$"77;'"((*3,+8'9-*(')-,'"/)$0%'0:'F)'206P(')0'P,,<'?('"('/0%()"%)'"('<0(5 ($47,8' 9-$(' %,&")$#,' :,,+4"/P' "/)$0%' 0:' F)' &$#,(' $)' )-,' %"3,' '&,&*&$(-)"*+ $&!)!-(*%&1' " %"3,')-")'2,'2$77'"<<6,/$"),'3*/-'4,)),6'")'"'7"),6'<0$%)'$%')-$('),B)8@Z I$&*6,' W8WQE4K' <60#$+,(' "' &6"<-$/"7' $77*()6")$0%' 0:' )-,' ,::,/)$#,%,((' 0:' )-$(' 4$"($%& (/-,3,8' !,6,' )00' 2,' (-02' )-,' +(Vv*)' /-"6"/),6$()$/(' :06' )20' +,#$/,(' )-")' 6,<6,(,%)' )-, ,B)6,3,('0:'"'4")/-'0:'FGHIJ9(8'H*<,6$3<0(,+'0%')-,'+,#$/,'/-"6"/),6$()$/('$('"'()6"$&-) 7$%,')-")'6,<6,(,%)(')-,'/0%()6"$%)'$3<0(,+'4;')-,'4$"('/$6/*$)p%"3,7;1'JO8'EW8[CK8'9-,'$%),65 (,/)$0%'0:')-$('()6"$&-)'7$%,'2$)-')-,'+(Vv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v($&')0')-, "3<7$:$,6'$%<*)'2$)-0*)'+$()*64$%&')-,'FGHIJ9'+/'4$"('<0$%)8'9-,'#"7*, 0:' <<@' (-0*7+' 4,' (,7,/),+' 7"6&,' ,%0*&-' )0' "<<60B$3"),' "' (-06)' /$6/*$)' ")' "77' ($&%"7' :6,5 O*,%/$,('0:'$%),6,()8'U,'(-"77'()*+;'/"<"/$)$#,7;'/0*<7,+'FGHIJ9'"3<7$:$,6(1'2-$/-'"6, (*$)"47,'0%7;'$%'+$(/6,),'/$6/*$)'+,($&%1'$%'H,/)$0%'W8d8'I$%"77;1'%0),')-")'$%')-,'/$6/*$)'0: I$&8'W8WQE/K1'6,($()06'F('$('(,7,/),+')0'4,'"('7"6&,'"('<0(($47,')0'04)"$%'-$&-'&"$%'4*)'(3"77 ,%0*&-')0'"7702':06')-,'+,($6,+'($&%"7'(2$%&'")')-,'+6"$%'2-$7,'P,,<$%&')-,'FGHIJ9'$% (")*6")$0%'")'"77')$3,(8' U-,%')20'<02,6'(*<<7$,('"6,'"#"$7"47,1'"('$('0:),%')-,'/"(,1')-,'(03,2-")'($3<7,6'4$"( "66"%&,3,%)'0:'I$&8'W8WQE,K'/"%'4,'*)$7$>,+8'9-$('/$6/*$)'$('"%'$3<7,3,%)")$0%'0:'JO8'EW8[CK1 2$)-'8*'6,<7"/,+'4;'8))8'i,($()06'F*',()"47$(-,('"'+/'&60*%+'")')-,'&"),'"%+'<6,(,%)('"'-$&$%<*)' 6,($()"%/,' )0' "' ($&%"7' (0*6/,' )-")' 3";' 4,' /0%%,/),+' )0' )-,' &"),' )-60*&-' "' /0*<7$%& /"<"/$)068
Example 5.12 =)'$('6,O*$6,+')0'+,($&%')-,'/$6/*$)'0:'I$&8'W8WQE/K')0',()"47$(-'"'+/'+6"$%'/*66,%)'?('='Z8W'3A8'9-,'FGHIJ9'$( Q (<,/$:$,+')0'-"#,'8#'='@'S'"%+ > !′' ⁄ & = @'3AcS 8'I06'($3<7$/$);1'%,&7,/)')-,'/-"%%,757,%&)-'30+*7")$0% ,::,/)'E$8,81'"((*3,'λ = 0K8'n(,'"'<02,65(*<<7;'8(('='@W'S8'?"7/*7"),')-,'<,6/,%)"&,'/-"%&,'$%')-,'#"7*,'0: ?('04)"$%,+'2-,%')-,'FGHIJ9'$('6,<7"/,+'2$)-'"%0)-,6'*%$)'-"#$%&')-,'("3, > !′' ⁄ &'4*)'8#'='@8W'S8
Solution A('"'6*7,'0:')-*34':06'+,($&%$%&')-$('/7"(($/"7'4$"($%&'/$6/*$)1'2,'/-00(,'F('"%+'F)')0'<60#$+,'0%,5)-$6+'0: )-,'<02,65(*<<7;'#07)"&,'8(('"('"'+60<'"/60((',"/-'0:'F(1')-,')6"%($()06'E$8,81'8()K'"%+'F)8'I06'8(('='@W'S1
9-,'"/)$0%'0:' F ) '$%'()"4$7$>$%&')-,'#"7*,'0:')-,'4$"('/*66,%)' ? ('$('%0)'*%7$P,')-")'0:')-,'6,($()"%/,' F 11 2-$/-'2,'$%/7*+,+'$%')-,'(0*6/,'7,"+'0:'"'?H'"3<7$:$,6'$%'H,/)$0%'W8N8b8'=%')-,'7")),6'/"(,'"7(01' F 1'206P( )0'6,+*/,')-,'/-"%&,'$%' + ('2$)-')-,'6,(*7)')-")')-,'"3<7$:$,6'&"$%'$('6,+*/,+8 @Z
310 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
Example 5.12 continued
)-$('/-0$/,'3"P,('8('='+@Z'S'"%+'8)'='+W'S8'`021'($%/,'?('$('6,O*$6,+')0'4,'Z8W'3A1'2,'/"%':$%+')-,'#"75 *,('0:'F('"%+'F)'"(':07702(D 8 (( ' 8 ( @W ' @Z 5 = 555555555555555555 = @Z'PΩ F ( = 5555555555555555555555 ?( Z8W 8 W F ) = 55555) = 5555555 = @Z'PΩ Z8W F) 9-,'6,O*$6,+'#"7*,'0:'8*)'/"%'4,'+,),63$%,+'4;':$6()'/"7/*7")$%&')-,'0#,6+6$#,'#07)"&,'8:8':603 Q
? ( = @55Q5 > !′ ( ' ⁄ & )8 :8 Z8W =
@ 555 Q
Q
× @ × 8 :8
2-$/-';$,7+('8:8'e'@'S1'"%+')-*(1' 8 *) = 8 # + 8 :8 = @ + @ = Q'S `021'($%/,'8)'='+W'S1'8*'3*()'4, 8 * = 8 ) + 8 *) = W + Q = f'S 90',()"47$(-')-$('#07)"&,'")')-,'&"),'2,'3";'(,7,/)'F*@'='d'FΩ'"%+'F*Q'='f'FΩ8'9-,':$%"7'/$6/*$)'$('(-02% $%'I$&8'W8WC8'G4(,6#,')-")')-,'+/'#07)"&,'")')-,'+6"$%'E+@Z'SK'"7702(':06'"'<0($)$#,'($&%"7'(2$%&'0:'+W'S E$8,81'*<')0'8((K'"%+'"'%,&")$#,'($&%"7'(2$%&'0:'Vb'S'q$8,81'+02%')0'E8*'V'8#Kr8' VDD " !15 V ID " 0.5 mA 8 M(
RD " 10 k( VD " !10 V
VG " !7 V VS " !5 V ID " 0.5 mA 7 M(
RS " 10 k(
Figure 5.53 ?$6/*$)':06'JB"3<7,'W8@Q8
5.7 Biasing in MOS Amplifier Circuits
=:')-,'`FGH')6"%($()06'$('6,<7"/,+'2$)-'"%0)-,6'-"#$%&'8#'='@8W'S1')-,'%,2'#"7*,'0:'?('/"%'4,':0*%+ "(':07702(D ?( =
@ 555 Q
× @ × ( 8 *) ' @8W )
Q
EW8[bK
8 * = 8 *) + ? ( F ) f = 8 *) + @Z? (
EW8[WK
H07#$%&'JO(8'EW8[bK'"%+'EW8[WK')0&,)-,6';$,7+( ? ( = Z8bWW'3A 9-*(')-,'/-"%&,'$%'?('$( ∆? ( = Z8bWW ' Z8W = ' Z8ZbW'3A ' Z8ZbW 2-$/-'$(' 55555555555555555 × @ZZ = ' [o'/-"%&,8 Z8W
EXERCISES 5.33' ?0%($+,6')-,'FGHIJ9'$%'JB"3<7,'W8@Q'2-,%':$B,+58*)'4$"('$('*(,+8'I$%+')-,'6,O*$6,+'#"7*,'0:'8*) )0 ,()"47$(-'"'+/'4$"('/*66,%)'?('='Z8W'3A8'i,/"77')-")')-,'+,#$/,'<"6"3,),6('"6,'8#'='@'S1 > !′' ⁄ & = Q @'3AcS 1 "%+'λ'='Z8'U-")'$(')-,'<,6/,%)"&,'/-"%&,'$%'?('04)"$%,+'2-,%')-,')6"%($()06'$('6,<7"/,+ 2$)-'"%0)-,6'-"#$%&'8#'='@8W'Sg Ans. 8*)'='Q'Sa'−fWo D5.34' ^,($&%')-,'/$6/*$)'0:'I$&8'W8WQE,K')0'0<,6"),'")'"'+/'+6"$%'/*66,%)'0:'Z8W'3A'"%+'8('='+Q'S8'T,)'8# Q ='@ S1''> !′' ⁄ & = @'3AcS 1 λ'='Z1'8(('='8))'='W'S8'n(,'()"%+"6+'Wo'6,($()06'#"7*,('E(,,'A<<,%+$B ]K1'"%+'&$#,')-,'6,(*7)$%&'#"7*,('0:''?(1'8(1'"%+'8)8 Ans. F('='F)'='N8Q'PΩa'?('='Z8b['3A1'8)'='−@8[N'S1'"%+'8('='+@8[N'S8'F*'/"%'4,'(,7,/),+'$%')-, 6"%&,'0:'@'FΩ')0'@Z'FΩ.
5.7.3 Biasing Using a Drain-to-Gate Feedback Resistor A'($3<7,'"%+',::,/)$#,'+$(/6,),5/$6/*$)'4$"($%&'"66"%&,3,%)'*)$7$>$%&'"':,,+4"/P'6,($()06'/0%5 %,/),+'4,)2,,%')-,'+6"$%'"%+')-,'&"),'$('(-02%'$%'I$&8'W8Wb8'!,6,')-,'7"6&,':,,+4"/P'6,($(5 )"%/,'F*'E*(*"77;'$%')-,'3,&0-3'6"%&,K':06/,(')-,'+/'#07)"&,'")')-,'&"),')0'4,',O*"7')0')-")'") )-,'+6"$%'E4,/"*(,'?*'='ZK8'9-*('2,'/"%'26$),
8 *) = 8 () = 8 (( ' F ( ? ( 2-$/-'/"%'4,'6,26$)),%'$%')-,':063
8 (( = 8 *) + F ( ? (
EW8[NK
311
312 Chapter 5 MOS Field-Effect Transistors (MOSFETs) 2-$/-'$('$+,%)$/"7'$%':063')0'JO8'EW8[CK1'2-$/-'+,(/6$4,(')-,'0<,6")$0%'0:')-,'4$"('(/-,3, +$(/*((,+' "40#,' q)-")' $%' I$&8' W8WQE"Kr8' 9-*(1' -,6,' )001' $:' ?(' :06' (03,' 6,"(0%' /-"%&,(1' ("; $%/6,"(,(1' )-,%' JO8' EW8[NK' $%+$/"),(' )-")' 8*)' 3*()' +,/6,"(,8' 9-,' +,/6,"(,' $%' 8*)' $%' )*6% /"*(,('"'+,/6,"(,'$%'?( 1'"'/-"%&,')-")'$('0<<0($),'$%'+$6,/)$0%')0')-,'0%,'06$&$%"77;'"((*3,+8 9-*(')-,'%,&")$#,':,,+4"/P'06'+,&,%,6")$0%'<60#$+,+'4;'F*'206P(')0'P,,<')-,'#"7*,'0:'?('"( /0%()"%)'"('<0(($47,8 9-,'/$6/*$)'0:'I$&8'W8Wb'/"%'4,'*)$7$>,+'"('"%'"3<7$:$,6'4;'"<<7;$%&')-,'$%<*)'#07)"&,'($&%"7 )0')-,'&"),'#$"'"'/0*<7$%&'/"<"/$)06'(0'"('%0)')0'+$()*64')-,'+/'4$"('/0%+$)$0%('"76,"+;',()"45 7$(-,+8'9-,'"3<7$:$,+'0*)<*)'($&%"7'")')-,'+6"$%'/"%'4,'/0*<7,+')0'"%0)-,6'<"6)'0:')-,'/$6/*$)1 "&"$%'#$"'"'/"<"/$)068'U,'-"#,'/0%($+,6,+'(*/-'"%'"3<7$:$,6'/$6/*$)'$%'H,/)$0%'W8W'EJB"3<7, W8@ZK8 VDD
RD 0
ID
RG
ID ! VDS
! VGS #
#
Figure 5.54 L$"($%&')-,'FGHIJ9'*($%&'"'7"6&,'+6"$%5)05&"),':,,+4"/P'6,($()"%/,1'F* 8
EXERCISE D5.35' ^,($&%' )-,' /$6/*$)' $%' I$&8' W8Wb' )0' 0<,6"),' ")' "' +/' +6"$%' /*66,%)' 0:' Z8W' 3A8' A((*3,'8((' =' +W Q S1 >′! ' ⁄ & = @'3AcS 1 '8#'='@'S1'"%+'λ'='Z8'n(,'"'()"%+"6+'Wo'6,($()"%/,'#"7*,':06'F(1'"%+'&$#, )-,'"/)*"7'#"7*,('04)"$%,+':06'?('"%+'8(8 Ans. F('='N8Q'PΩa' ? ( " Z8b['3Aa 8 ( " @8[N'S
5.7.4 Biasing Using a Constant-Current Source 9-,'30()',::,/)$#,'(/-,3,':06'4$"($%&'"'FGHIJ9'"3<7$:$,6'$(')-")'*($%&'"'/0%()"%)5/*66,%) (0*6/,8'I$&*6,'W8WWE"K'(-02('(*/-'"%'"66"%&,3,%)'"<<7$,+')0'"'+$(/6,),'FGHIJ98'!,6,'F* E*(*"77;'$%')-,'3,&0-3'6"%&,K',()"47$(-,('"'+/'&60*%+'")')-,'&"),'"%+'<6,(,%)('"'7"6&,'6,($(5 )"%/,' )0' "%' $%<*)' ($&%"7' (0*6/,' )-")' /"%' 4,' /"<"/$)$#,7;' /0*<7,+' )0' )-,' &"),8' i,($()06' F( ,()"47$(-,(' "%' "<<60<6$"),' +/' #07)"&,' ")' )-,' +6"$%' )0' "7702' :06' )-,' 6,O*$6,+' 0*)<*)' ($&%"7 (2$%&'2-$7,',%(*6$%&')-")')-,')6"%($()06'"72";('6,3"$%('$%')-,'(")*6")$0%'6,&$0%8
5.7 Biasing in MOS Amplifier Circuits
VDD
VDD
RD ID " I Q
To source of transistor Q in Fig. 5.55 (a)
R IREF
0
ID2
ID1
RG
Q1 I
#VSS
! VGS #
Q2
#VSS
(a)
(b)
Figure 5.55 1(2' L$"($%&' )-,' FGHIJ9' *($%&' "' /0%()"%)5/*66,%)' (0*6/,' ?8' 1/2' =3<7,3,%)")$0%' 0:' )-, /0%()"%)5/*66,%)'(0*6/,'?'*($%&'"'/*66,%)'3$66068
A'/$6/*$)':06'$3<7,3,%)$%&')-,'/0%()"%)5/*66,%)'(0*6/,'?'$('(-02%'$%'I$&8'W8WWE4K8'9-, -,"6)'0:')-,'/$6/*$)'$(')6"%($()06';@1'2-0(,'+6"$%'$('(-06),+')0'$)('&"),1'"%+')-*('$('0<,6")$%&'$% )-,'(")*6")$0%'6,&$0%1'(*/-')-")'
@ ' Q ? (@ = 555 > !′ 55555 ( 8 *) ' 8 # ) ' Q &@
EW8[fK
2-,6,'2,'-"#,'%,&7,/),+'/-"%%,757,%&)-'30+*7")$0%'E$8,81'"((*3,+'λ'='ZK8'9-,'+6"$%'/*66,%) 0:';@'$('(*<<7$,+'4;'8((')-60*&-'6,($()06'F8'H$%/,')-,'&"),'/*66,%)('"6,'>,601
8 (( + 8 )) ' 8 *) 5 ? (@ = ? iJI = 5555555555555555555555555555555555555 F
EW8[dK
2-,6,')-,'/*66,%)')-60*&-'F'$('/0%($+,6,+')0'4,')-,'6/M/6/!./0.-66/!#'0:')-,'/*66,%)'(0*6/, "%+'$('+,%0),+'?iJI8']$#,%')-,'<"6"3,),6'#"7*,('0:';@'"%+'"'+,($6,+'#"7*,':06'?iJI1'JO(8'EW8[fK "%+'EW8[dK'/"%'4,'*(,+')0'+,),63$%,')-,'#"7*,'0:'F8'`02'/0%($+,6')6"%($()06';QD'=)'-"(')-, ("3,'8*)'"(';@a')-*('$:'2,'"((*3,')-")'$)'$('0<,6")$%&'$%'(")*6")$0%1'$)('+6"$%'/*66,%)1'2-$/-'$( )-,'+,($6,+'/*66,%)'?'0:')-,'/*66,%)'(0*6/,1'2$77'4,
@ ' Q ? = ? (Q = 555 > !′ 55555 ( 8 *) ' 8 # ) Q & Q
EW8[[K
2-,6,'2,'-"#,'%,&7,/),+'/-"%%,757,%&)-'30+*7")$0%8'JO*")$0%('EW8[dK'"%+'EW8[[K',%"47,'*( )0'6,7"),')-,'/*66,%)'?')0')-,'6,:,6,%/,'/*66,%)'?iJI1
(' ⁄ &) ? = ? iJI 5555555555555555555Q ( ' ⁄ & )@
EW8@ZZK
9-*('?'$('6,7"),+')0'?iJI'4;')-,'6")$0'0:')-,'"(<,/)'6")$0('0:';@'"%+';Q8'9-$('/$6/*$)1'P%02%'"('" %#$$&*-+B)$$"$1'$('#,6;'<0<*7"6'$%')-,'+,($&%'0:'=?'FGH'"3<7$:$,6('"%+'2$77'4,'()*+$,+'$% &6,")'+,)"$7'$%'?-"<),6'f8
313
314 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
EXERCISE D5.36 n($%&')20')6"%($()06(';@'"%+';Q'-"#$%&',O*"7'7,%&)-('4*)'2$+)-('6,7"),+'4;'' Q ⁄ ' @ = W1'+,($&%')-, Q /$6/*$)'0:'I$&8'W8WWE4K')0'04)"$%'?'='Z8W'3A8'T,)'8(('=' −8))' =' W'S1 > !′ ( ' ⁄ & ) @ = Z8d'3AcS 108#'= @ S1'"%+'λ'='Z8'I$%+')-,'6,O*$6,+'#"7*,':06'F8'U-")'$(')-,'#07)"&,'")')-,'&"),('0:';@'"%+';Qg'U-") $(')-,'702,()'#07)"&,'"7702,+'")')-,'+6"$%'0:';Q'2-$7,';Q'6,3"$%('$%')-,'(")*6")$0%'6,&$0%g Ans. dW'PΩa'−C8W'Sa'−b8W'S
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318 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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322 Chapter 5 MOS Field-Effect Transistors (MOSFETs)
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Vo (dB) Vsig
Low-frequency band
High-frequency band
Midband • All capacitances can be neglected
• Gain falls off due to the effect of CC1, CS, and CC2
• Gain falls off due to the internal capacitive effects of the MOSFET
3 dB
20 log |AM| (dB)
fH
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Section 5.2: Current–Voltage Characteristics
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CHAPTER 5
Section 5.3: MOSFET Circuits at DC
CHAPTER 5
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CHAPTER 6
Bipolar Junction Transistors (BJTs) Introduction 6.1
351
Device Structure and Physical Operation 352
6.2 Current–Voltage Characteristics 365 6.3 BJT Circuits at DC
378
6.4 Applying the BJT in Amplifier Design 396 6.5 Small-Signal Operation and Models 403
6.6 Basic BJT Amplifier Configurations 422 6.7 Biasing in BJT Amplifier Circuits 446 6.8 Discrete-Circuit BJT Amplifiers
453
6.9 Transistor Breakdown and Temperature Effects 463 Summary
465
Problems
466
IN THIS CHAPTER YOU WILL LEARN 1. The physical structure of the bipolar transistor and how it works. 2. How the voltage between two terminals of the transistor controls the current that flows through the third terminal, and the equations that describe these current–voltage characteristics. 3. How to analyze and design circuits that contain bipolar transistors, resistors, and dc sources. 4. How the transistor can be used to make an amplifier. 5. How to obtain linear amplification from the fundamentally nonlinear BJT. 6. The three basic ways for connecting a BJT to be able to construct amplifiers with different properties. 7. Practical circuits for bipolar-transistor amplifiers that can be constructed by using discrete components.
Introduction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
351
352 Chapter 6 Bipolar Junction Transistors (BJTs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
6.1 Device Structure and Physical Operation 6.1.1 Simplified Structure and Modes of Operation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
6.1 Device Structure and Physical Operation
Emitter (E)
n-type
p-type
n-type
Emitter region
Base region
Collector region
Emitter–base junction (EBJ)
Base (B)
Metal contact Collector (C)
Collector–base junction (CBJ)
Figure 6.1 I#'&3*6&@&+0#'$,/($/,+#2@#$%+#!"!#$,)"'&'$2,?
Metal contact E
p
n
p
Emitter region
Base region
Collector region
C
B Figure 6.2 I#'&3*6&@&+0#'$,/($/,+#2@#$%+#"!"#$,)"'&'$2,?
Table 6.1 BJT Modes of Operation A20+
E;<
F;<
F/$2@@ I($&7+ C)$/,)$&2"
J+7+,'+ D2,.),0 D2,.),0
J+7+,'+ J+7+,'+ D2,.),0
@0,4$,4(++,0$$,0"2#&+:5,/"*#;$,/*##($#0,21,92&",72+*#(&($0[&"*&,(05,$+$/)0,*)-,"2+$0[ 7*#&(/(7*&$,(),&"$,/3##$)&%/2)-3/&(2),7#2/$00,(),*,9(72+*#,*)0(0&2#5,4"(/",(0,&"$,#$*02),12# &"$,)*'$,#$"%&'(,,
6.1.2 Operation of the npn Transistor in the Active Mode J1,&"$,&"#$$,'2-$0,21,27$#*&(2),21,&"$,BC!5,&"$,*/&(.$,'2-$,(0,&"$,'20&,('72#&*)&<,!"$#$12#$5 4$,9$;(),23#,0&3-:,21,&"$,BC!,9:,/2)0(-$#();,(&0,7":0(/*+,27$#*&(2),(),&"$,*/&(.$,'2-$
=%&'#'%2/60#9+#(2"$,)'$+0#.&$%#$%+#'&$/)$&2"#&"#$%+#ABCDE=-#.%+,+#(/,,+"$#&'#(2"0/($+0#91#(%),L+ (),,&+,'#2@#2"+#$1*+#2"61H#+6+($,2"'#&"#!5(%)""+6#0+7&(+'#2,#%26+'#&"#"5(%)""+6#0+7&(+'?#!"#+),6&+,#0)1''23+#,+@+,,+0#$2#DE='#)'#/"&*26),#0+7&(+'? M =%+#3)$+,&)6#&"#$%&'#'+($&2"#)''/3+'#$%)$#$%+#,+)0+,#&'#@)3&6&),#.&$%#$%+#2*+,)$&2"#2@#$%+#"!#4/"($&2" /"0+,#@2,.),059&)'#(2"0&$&2"'#:C+($&2"#N?G>?
353
354 Chapter 6 Bipolar Junction Transistors (BJTs) Reverse-biased
Forward-biased n
Diffusing electrons
Injected electrons
E
Collected electrons
iC
C
iB2
iE
iE
n
p
Injected holes (iB1)
iC
Recombined electrons (iB2)
iB –
v BE
iB
+
iE
iE VBE
B
–
v CB
+ iC
iC VCB
Figure 6.3 73''#./$ %5&($ ,.$ ).$ %$%$ /').-,-/&'$ +,)-#*$ /&$ &8#')/#$ ,.$ /"#$ )4/,>#$ 0&*#6$ ?J#>#'-#$ 43''#./ 4&08&.#./-$*3#$/&$*',%/$&%$/"#'0)55<$=#.#')/#*$0,.&',/<$4)'',#'-$)'#$.&/$-"&(.6@
!"#!"#$%&%!'(&!$)'*+&!,#%&!'-!,&!(./(&0!.1!+-'&1'.#2!'(#1!'(&!%)'*+&!&3.''&04!'($%!5-06#07),.#%.1/ '(&!&3.''&08,#%&!9$1"'.-1:!;(&!"-22&"'-08,#%&!<-2'#/&!!&"!"#$%&%!'(&!%)'*+&!"-22&"'-0!'-!,&!#'!# (./(&0!+-'&1'.#2!'(#1!'(&!$)'*+&!,#%&4!'($%!0&<&0%&),.#%.1/!'(&!"-22&"'-08,#%&!9$1"'.-1: Current Flow !"#$%&'()'*$+,)-$&.$/"#$#0,//#'1+)-#$23.4/,&.$(,55$4)3-#$43''#./$/&$%5&($)4'&-/",-$23.4/,&.6$73''#./$(,55$4&.-,-/$&%$/(&$4&08&.#./-9$#5#4/'&.-$,.2#4/#*$%'&0$/"#$#0,//#'$,./&$/"# +)-#:$).*$"&5#-$,.2#4/#*$%'&0$/"#$+)-#$,./&$/"#$#0,//#'6$;-$(,55$+#4&0#$)88)'#./$-"&'/5<:$,/$,-$",="5< *#-,')+5#$/&$")>#$/"#$%,'-/$4&08&.#./$?#5#4/'&.-$%'&0$#0,//#'$/&$+)-#@$)/$)$034"$",="#'$5#>#5$/"). /"#$-#4&.*$4&08&.#./$?"&5#-$%'&0$+)-#$/&$#0,//#'@6$!",-$4).$+#$)44&085,-"#*$+<$%)+',4)/,.=$/"# *#>,4#$(,/"$)$"#)>,5<$*&8#*$#0,//#'$).*$)$5,="/5<$*&8#*$+)-#A$/")/$,-:$/"#$*#>,4#$,-$*#-,=.#*$/&$")># )$",="$*#.-,/<$&%$#5#4/'&.-$,.$/"#$#0,//#'$).*$)$5&($*#.-,/<$&%$"&5#-$,.$/"#$+)-#6 !"#$43''#./$/")/$%5&(-$)4'&--$/"#$#0,//#'1+)-#$23.4/,&.$(,55$4&.-/,/3/#$/"#$#0,//#'$43''#./$'#:$),.*,4)/#*$,.$B,=6$C6D6$!"#$*,'#4/,&.$&%$'#$,-$E&3/$&%F$/"#$#0,//#'$5#)*:$(",4":$%&55&(,.=$/"#$3-3)5 4&.>#./,&.-:$ ,-$ ,.$ /"#$ *,'#4/,&.$ &%$ /"#$ 8&-,/,>#G4")'=#$ %5&($ ?"&5#$ 43''#./@$ ).*$ &88&-,/#$ /&$ /"# *,'#4/,&.$&%$/"#$.#=)/,>#G4")'=#$%5&($?#5#4/'&.$43''#./@:$(,/"$/"#$#0,//#'$43''#./$'#$+#,.=$#H3)5$/& /"#$-30$&%$/"#-#$/(&$4&08&.#./-6$I&(#>#':$-,.4#$/"#$#5#4/'&.$4&08&.#./$,-$034"$5)'=#'$/"). /"#$"&5#$4&08&.#./:$/"#$#0,//#'$43''#./$(,55$+#$*&0,.)/#*$+<$/"#$#5#4/'&.$4&08&.#./6 =&'!$%!1-6!"-1%.7&0!'(&!&2&"'0-1%!.19&"'&7!50-3!'(&!&3.''&0!.1'-!'(&!,#%&:!;(&%&!&2&"'0-1% 6.22!,&!!"#$%"&'()*%%"+%,!.1!'(&!$)'*+&!,#%&!0&/.-1:!>&"#$%&!'(&!,#%&!.%!$%$#22*!<&0*!'(.14 .1 '(&!%'*!%'#'&!'(&!&?"&%%!3.1-0.'*!"#00.&0!@&2&"'0-1A!"-1"&1'0#'.-1!.1!'(&!,#%&!6.22!(#<& #1!#23-%')%'0#./(')2.1&!+0-5.2&4!#%!.17."#'&7!,*!'(&!%-2.7!%'0#./('!2.1&!.1!B./:!C:D:!;(&!&2&"'0-1 "-1"&1'0#'.-1!6.22!,&!(./(&%'!E7&1-'&7!,*!%$@FAG!#'!'(&!&3.''&0!%.7&!#17!2-6&%'!@H&0-A!#'!'(& "-22&"'-0! %.7&:I! J%! .1! '(&! "#%&! -5! #1*! 5-06#07),.#%&7! $%! 9$1"'.-1! @K&"'.-1! I:LA4! '(& v ⁄! "-1"&1'0#'.-1! % $ ( O ) 6.22!,&!+0-+-0'.-1#2!'-! ( "# ) : D
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6.1 Device Structure and Physical Operation
Carrier concentration
Emitter (n)
EBJ depletion region
Base (p)
CBJ depletion region
Collector (n)
Electron concentration np (ideal) Hole concentration
pn0
np (0)
pn (0)
np (with recombination)
Distance (x)
Effective base width W Figure 6.4 O,2@&6+'#2@#3&"2,&$15(),,&+,#(2"(+"$,)$&2"'#&"#$%+#9)'+#)"0#&"#$%+#+3&$$+,#2@#)"#!"!#$,)"'&'$2, 2*+,)$&"L#&"#$%+#)($&7+#320+8# v )* > P #)"0# v -) ≥ P ?
! " ( P ) = ! "P 4
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360 Chapter 6 Bipolar Junction Transistors (BJTs)
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, + -* d G ] N × K d c#M#]## C&"(+# + - #)$#cM#]#&'#%&L%+,#$%)"# + ) #)$#P?Wa#]-#$%+#$,)"'&'$2,#&'#&"0++0#2*+,)$&"L#&"#$%+#)($&7+#320+? b2.-#,+*6)(&"L#$%+#KP5µI#(/,,+"$#'2/,(+#.&$%#)#,+'&'$)"(+# > ) #(2""+($+0#@,23#$%+#9)'+#$2#$%+#G5]#0( '/**61# + -- -#)'#&"#D&L?#W?W:9>-#$%+#7)6/+#2@# > ) #3/'$#9+ + -- ] + )* > ) d 5555555555555555555555555 5 .) ] P?Wa5 d eNK#UΩ d G 555555555555555555 KP µI ,
EXERCISES 6.1
F2"'&0+,#)"#!"!#$,)"'&'$2,#.&$%#v)*#=#P?d#]#)$#$-#=#K#3I?#D&"0#v)*#)$#$-#=#P?K#3I#)"0#KP#3I? Ans. P?We#]H#P?dW#]
6.2
=,)"'&'$2,'#2@#)#(+,$)&"#$1*+#),+#'*+(&@&+0#$2#%)7+#β#7)6/+'#&"#$%+#,)"L+#GP#$2#KGP?#D&"0#$%+#,)"L+#2@ $%+&,#α#7)6/+'? Ans. P?afP#$2#P?aaN
6.3
A+)'/,+3+"$#2@#)"#!"!#;<=#&"#)#*),$&(/6),#(&,(/&$#'%2.'#$%+#9)'+#(/,,+"$#$2#9+#Ke?eW#µI-#$%+#+3&$5 $+,#(/,,+"$#$2#9+#K?eWP#3I-#)"0#$%+#9)'+Q+3&$$+,#726$)L+#$2#9+#P?d#]?#D2,#$%+'+#(2"0&$&2"'-#()6(/6)$+ α-#β-#)"0#.6? Ans. P?aaH#KPPH#KPQKG#I
6.4
F)6(/6)$+#β#@2,#$.2#$,)"'&'$2,'#@2,#.%&(%#α#=#P?aa#)"0#P?af?#D2,#(266+($2,#(/,,+"$'#2@#KP#3I-#@&"0 $%+#9)'+#(/,,+"$#2@#+)(%#$,)"'&'$2,? Ans. aaH#eaH#P?K#3IH#P?M#3I
6.1 Device Structure and Physical Operation
6.5
I#$,)"'&'$2,#@2,#.%&(%#.C#`#KPQKW#I#)"0#β# `#KPP##&'#(2"0/($&"L#)#(266+($2,#(/,,+"$#2@#K#3I?#D&"0#v)*? I6'2-#@&"0#.6*8)"0#.6)8@2,#$%&'#$,)"'&'$2,? ] KW Ans. ded?G#3]H# K?PK × KP I H#KPQKfI
6.6
D2,#$%+#(&,(/&$#&"#D&L?#W?W:)>#)")61h+0#&"#ET)3*6+#W?K-#@&"0#$%+#3)T&3/3#7)6/+#2@# > - #$%)$#.&66#'$&66 ,+'/6$#&"#)($&7+5320+#2*+,)$&2"? Ans. e?NK#U Ω
6.1.3 Structure of Actual Transistors L(;3#$,X
E
p
B
C
n n
Figure 6.7 F,2''5'+($&2"#2@#)"#!"!#;<=?
!"$,0/&3#$,(),L(;<,X
EXERCISE 6.7
e
] KG
I#*),$&(/6),#$,)"'&'$2,#%)'# . 6 d KP I #)"0# α ! K?#!@#$%+#F;<#),+)#&'#KPP#$&3+'#$%+#),+)#2@#$%+#E;<@&"0#$%+#(266+($2,#'()6+#(/,,+"$# . 6- ? ] KN Ans. KP #I
!@#$%+#+3&$$+,#)"0#(266+($2,#),+#,+7+,'+0g$%)$#&'-#$%+#F;<#&'#@2,.),0#9&)'+0#)"0#$%+#E;<#&'#,+7+,'+ 9&)'+0g$%+#0+7&(+#2*+,)$+'#&"#)#320+#()66+0#$%+#R,+7+,'+5)($&7+#320+?S#=%+#,+'/6$&"L#7)6/+'#2@#α )"0 β-#0+"2$+0#α> )"0#β>#:.&$%#>#0+"2$&"L#,+7+,'+>-#),+#3/(%#62.+,#$%)"#$%+#7)6/+'#2@#α )"0#β-#,+'*+($&7+6129$)&"+0#&"#$%+#R@2,.),0S#)($&7+#320+#0&'(/''+0#)927+?#\+"(+-#$%+#,+7+,'+5)($&7+#320+#%)'#"2#*,)($&()6 )**6&()$&2"?#=%+#ABCDE=-#2"#$%+#2$%+,#%)"0-#9+&"L#)#*+,@+($61#'133+$,&()6#0+7&(+-#()"#2*+,)$+#+V/)661 .+66#.&$%#&$'#0,)&"#)"0#'2/,(+#$+,3&")6'#&"$+,(%)"L+0?#
361
362 Chapter 6 Bipolar Junction Transistors (BJTs)
6.1.4 Operation in the Saturation Mode5 I'#3+"$&2"+0#)927+-#@2,#$%+#;<=#$2#2*+,)$+#&"#$%+#)($&7+#320+-#$%+#F;<#3/'$#9+#,+7+,'+ 9&)'+0?#=%/'#@),-#.+#%)7+#'$)$+0#$%&'#(2"0&$&2"#@2,#$%+#!"!#$,)"'&'$2,#)'# v -) ≥ P?#\2.+7+,.+#U"2.#$%)$#)#"!#4/"($&2"#02+'#"2$#+@@+($&7+61#9+(23+#@2,.),0#9&)'+0#/"$&6#$%+#@2,.),0 726$)L+#)(,2''#&$#+T(++0'#)**,2T&3)$+61#P?e#]?#!$#@2662.'#$%)$#2"+#()"#3)&"$)&"#)($&7+5320+ 2*+,)$&2"#2@#)"#!"!#$,)"'&'$2,#@2,#"+L)$&7+# v -) #02."#$2#)**,2T&3)$+61# ] P?e ]?#=%&'#&'#&66/'5 $,)$+0#&"#D&L?#W?f-#.%&(%#&'#)#'U+$(%#2@# $ - #7+,'/'# v -) #@2,#)"#!"!#$,)"'&'$2,#2*+,)$+0#.&$%#) (2"'$)"$#+3&$$+,#(/,,+"$# . * ?#I'#+T*+($+0-# $ - #&'#&"0+*+"0+"$#2@# v -) #&"#$%+#)($&7+#320+-#)#'&$5 /)$&2"# $%)$# +T$+"0'# @2,# v -) # L2&"L# "+L)$&7+# $2# )**,2T&3)$+61# ] P?e ]?# ;+62.# $%&'# 7)6/+# 2@ v -)-#$%+# F;<#9+L&"'#$2# (2"0/($#'/@@&(&+"$61#$%)$#$%+#$,)"'&'$2,#6+)7+'# $%+#)($&7+#320+# )"0 +"$+,'#$%+#')$/,)$&2"#320+#2@#2*+,)$&2"-#.%+,+# $ - #0+(,+)'+'? =2#'++#.%1# $ - #0+(,+)'+'#&"#')$/,)$&2"-#.+#()"#(2"'$,/($#)#320+6#@2,#$%+#')$/,)$+0#!"! $,)"'&'$2,#)'#@2662.'?#Y+#)/L3+"$#$%+#320+6#2@#D&L?#W?G:(>#.&$%#$%+#@2,.),05(2"0/($&"L#F;< 0&20+# 1 - -#)'#'%2."#&"#D&L?#W?a?#B9'+,7+#$%)$#$%+#(/,,+"$# $ )- #.&66#'/9$,)($#@,23#$%+#(2"5 $,266+05'2/,(+#(/,,+"$-#,+'/6$&"L#&"#$%+#,+0/(+0#(266+($2,#(/,,+"$# $ - #L&7+"#91 $- d .6 4
v )* ⁄ + ,
] . 6- 4
v )- ⁄ + ,
TX8V
=%+# '+(2"0# $+,3# .&66# *6)1# )"# &"(,+)'&"L# ,26+# )'# v )- # +T(++0'# P?e# ]# 2,# '2-# ()/'&"L# $ - # $2 0+(,+)'+#)"0#+7+"$/)661#,+)(%#h+,2?# L(;3#$,X
v )* ⁄ + ,
e . 6- 4
v )- ⁄ + ,
TX^V
iC Saturation mode
Active mode aIE
%0.4 V
0
iE " IE
vCB
Expanded scale Figure 6.8 =%+#$- Qv-)#(%),)($+,&'$&(#2@#)"#!"!#$,)"'&'$2,#@+0#.&$%#)#(2"'$)"$#+3&$$+,#(/,,+"$#.*?#=%+#$,)"'&'5 $2,#+"$+,'#$%+#')$/,)$&2"#320+#2@#2*+,)$&2"#@2,#v-)#i#QP?e#]-#)"0#$%+#(266+($2,#(/,,+"$#0&3&"&'%+'? G
C)$/,)$&2"#&"#)#;<=#3+)"'#'23+$%&"L#(23*6+$+61#0&@@+,+"$#@,23#$%)$#&"#)#ABCDE=?#=%+#')$/,)$&2" 320+#2@#2*+,)$&2"#2@#$%+#;<=#&'#)")62L2/'#$2#$%+#$,&20+#,+L&2"#2@#2*+,)$&2"#2@#$%+#ABCDE=?#B"#$%+ 2$%+,#%)"0-#$%+#')$/,)$&2"#,+L&2"#2@#2*+,)$&2"#2@#$%+#ABCDE=#(2,,+'*2"0'#$2#$%+#)($&7+#320+#2@#;<= 2*+,)$&2"?
6.1 Device Structure and Physical Operation
/
ISC e vBC VT
iB B $
iC C
vBE
DB
DC
/
ISe vBE VT
% E
Figure 6.9 A20+6&"L#$%+#2*+,)$&2"#2@#)"#!"!#$,)"5 '&'$2,# &"# ')$/,)$&2"# 91# )/L3+"$&"L# $%+# 320+6# 2@ D&L? W?G:(>#.&$%#)#@2,.),0#(2"0/($&"L#0&20+#1- ?#b2$+ $%)$#$%+#(/,,+"$#$%,2/L%#1-#&"(,+)'+'#$)#)"0#,+0/(+'#$-?
EV/)$&2"'#:W?Ke>#)"0#:W?KG>#()"#9+#(239&"+0#$2#29$)&"#$%+#,)$&2# $ - ⁄ $ ) #@2,#)#')$/,)$+0#$,)"'&'$2,? Y+#29'+,7+#$%)$#$%&'#,)$&2#.&66#9+#&%A4(#$%)"#$%+#7)6/+#2@# β ? #D/,$%+,32,+-#$%+#,)$&2#.&66#0+(,+)'+ )'# v )- #&'#&"(,+)'+0#)"0#$%+#$,)"'&'$2,#&'#0,&7+"#0++*+,#&"$2#')$/,)$&2"?#;+()/'+# $ - ⁄ $ ) #2@#)#')$/5 ,)$+0#$,)"'&'$2,#()"#9+#'+$#$2#)"1#0+'&,+0#7)6/+#62.+,#$%)"# β #91#)04/'$&"L# v )- - #$%&'#,)$&2#&'#U"2." )'#3*%)!2-β )"0#0+"2$+0#β@2,(+0-# $ $)
β @2,(+0 d 555-5
,≤ β
TX
')$/,)$&2"
@0,4(++,9$,0"24),+*&$#5,(),*)*+:>();,*,/(#/3(&,4$,/*),-$&$#'()$,4"$&"$#,&"$,BC!,(0,(),&"$ 0*&3#*&(2),'2-$,9:,$(&"$#,21,&"$,12++24();,&42,&$0&0Y 1. =0,&"$,6BC,12#4*#-,9(*0$-,9:,'2#$,&"*),O<8,_f, 2. !'#$%+#,)$&2# $ - ⁄ $ ) #62.+,#$%)"# β _ !"$,/2++$/&2#%&2%$'(&&$#,.2+&*;$, v -* ,21,*,0*&3#*&$-,*)0(0&2#,/*),9$,123)-,1#2',L(;<,X
TX
J+()66&"L#$%)$#$%+#F;<#%)'#)#3/(%#6),L+,#),+)#$%)"#$%+#E;<-# + )- #.&66#9+#'3)66+,#$%)"# + )* 91#P?K#$2#P?N#]?#=%/'+ -*')$ ! P?K ,&2,O<\,_
=1*&()661# .+# .&66# )''/3+# $%)$# )# $,)"'&'$2,# )$# $%+# +0L+# 2@# ')$/,)$&2"# %)'# + -*')$ d P?N # ].%&6+#)#$,)"'&'$2,#0++*#&"#')$/,)$&2"#%)'# + -*')$# d P?M #]?
EXERCISES 6.8
^'+#EV?#:W?Ke>#$2#'%2.#$%)$# $ - #,+)(%+'#h+,2#)$# + -* d + , 6" ( . 6- ⁄ . 6 ) F)6(/6)$+# + -* #@2,#)#$,)"'&'$2,#.%2'+#F;<#%)'#KPP#$&3+'#$%+#),+)#2@#$%+#E; Ans. KKG#3]
6.9
^'+#EV'?#:W?Ke>-#:W?KG>-#)"0#:W?KW>#$2#'%2.#$%)$#)#;<=#2*+,)$&"L#&"#')$/,)$&2"#.&$%# +-* d +-*')$ %)'#)#@2,(+0# β #L&7+"#91 + -*')$ ⁄ + , 4 ] . 6- ⁄ . 6 5 β @2,(+0 d β 555555555555555555555555555555555555555555555 + -*')$ ⁄ + , 4 e β . 6- ⁄ . 6 D&"0#β@2,(+0#@2,# β d KPP-# . 6- ⁄ . 6 d KPP-#)"0# + -*')$ d P?M #]? Ans. MM?M
363
364 Chapter 6 Bipolar Junction Transistors (BJTs)
6.1.5 The pnp Transistor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v%$$"')$%+$3# ,.'2#0$3>$ v$%4$E.)+?$%"#$.'&6#=)*6('.?$'2%*1#=-+0#$+,#&'%*+($+/$%"#$!"!$%&'()*)%+&$2'($3# -+0#.#0$3>$'(>$+/$/+7&$#K7*1'.#(%$2*&27*%)$)*-*.'&$%+$%"+)#$/+&$%"#$"!"$%&'()*)%+&$*($5*64 84L4$!;+$+/$%"#)#$/+7&$2*&27*%)$'$)"+;($*($5*64$84994$5*('..>?$;#$(+%#$%"'%$%"#$!"!$%&'(= )*)%+&$2'($+,#&'%#$*($%"#$)'%7&'%*+($-+0#$*($'$-'((#&$'('.+6+7)$%+$%"'%$0#)2&*3#0$/+&$%"# "!"$0#1*2#4 Reverse-biased
Forward-biased p
E
Diffusing holes
Injected holes
iE iE
p
n
iC
Collected holes
iB2
Injected electrons
iC C
Recombined holes
iB1 iB +
v EB
iB
–
iE
iE VEB
B
+
v BC
–
iC VBC
Figure 6.10 !"##$%&'()*+',%'-'!"!'-%.,.&*#'/,-.$0'&*'*1$#-&$',%'&2$'-3&,4$'5*0$6
iC
6.2 Current–Voltage Characteristics
iE iE
D (IS"aF)
iB
$ vEB %
IS evEB"VT iC
E
IS e vEB "VT
DB (IS "b)
B
C iB
(a)
iC (b)
Figure 6.11 =.2#6),L+5'&L")6#320+6'#@2,#$%+#"!"#$,)"'&'$2,#2*+,)$&"L#&"#$%+#)($&7+#320+?
,, EXERCISES 6.10 F2"'&0+,#$%+#320+6#&"#D&L?#W?KK:)>#)**6&+0#&"#$%+#()'+#2@#)#"!"#$,)"'&'$2,#.%2'+#9)'+#&'#L,2/"0+0$%+#+3&$$+,#&'#@+0#91#)#(2"'$)"$5(/,,+"$#'2/,(+#$%)$#'/**6&+'#)#M53I#(/,,+"$#&"$2#$%+#+3&$$+,#$+,3&")6)"0#$%+#(266+($2,#&'#(2""+($+0#$2#)#Q KP5]#0(#'/**61?#D&"0#$%+#+3&$$+,#726$)L+-#$%+#9)'+#(/,,+"$-#)"0 $%+#(266+($2,#(/,,+"$#&@#@2,#$%&'#$,)"'&'$2,#β#=#GP#)"0#.6#=#KPQKe#I? Ans. P?WGP#]H#Na?M#µIH#K?aW#3I 6.11
D2,#)#"!"#$,)"'&'$2,#%)7&"L#.6#=#KPQKK#I#)"0#β#=#KPP-#()6(/6)$+#v*)#@2,#$-#=#K?G#I? Ans. O
6.2 Current–Voltage Characteristics 6.2.1 Circuit Symbols and Conventions !"$,7":0(/*+,0/&3#$,30$-,&"30,1*#,&2,$A7+*(),*)0(0&2#,27$#*&(2),(0,#*&"$#,/3'9$#02'$,&2 $'7+2:,(),-#*4();,&"$,0/"$'*&(/,21,*,'3+&(*)0(0&2#,/(#/3(&<,L2#&3)*&$+:5,*,.$#:,-$0/#(7&(.$ *)-,/2).$)($)&,/(#/3(&,0:'92+,$A(0&0,12#,&"$,BC!<,L(;3#$,X();,&42,-/,.2+&*;$,023#/$05
365
366 Chapter 6 Bipolar Junction Transistors (BJTs)
npn
pnp
(a)
(b)
(a)
Figure 6.12 F&,(/&$#'13926'#@2,#;<='?
(b)
Figure 6.13 ]26$)L+#*26),&$&+'#)"0#(/,,+"$#@62.#&"#$,)"'&'$2,'#9&)'+0#&"#$%+#)($&7+#320+?
(0,)2&,*,303*+,2)$,*)-,(0,30$-,"$#$,'$#$+:,&2,(++30*&$,27$#*&(2)<,g#*/&(/*+,9(*0();,0/"$'$0 4(++,9$,7#$0$)&$-,(),K$/&(2),X
6.2 Current–Voltage Characteristics
L#2',&"$,-(0/300(2),21,K$/&(2),X,(&,12++240,&"*&,*),!"!,*)0(0&2#,4"20$,MBC,(0,12#4*#9(*0$-,4(++,27$#*&$,(),&"$,*/&(.$,'2-$,'B8&%!C8'B8?D48E%&&4E?%(,F%&?'C485%4B8!%?8G'&&8#4&%A ?D'?8 %G8 ?D48 #'B48 #H8 I%(48 ?D'!8 '""(%3$I'?4&H8 J@K8 +<, J&"$#4(0$5, &"$, *)0(0&2#, +$*.$0, &"$ */&(.$,'2-$,*)-,$)&$#0,&"$,0*&3#*&(2),#$;(2),21,27$#*&(2)
Table 6.2 Summary of the BJT Current–Voltage Relationships in the Active Mode v )* ⁄ + ,
$- = .6 4 $ . v)* ⁄ +, $ ) = 555-5 = 55565 4
β
β
α
α
$ . v)* ⁄ +, $ * = 555-5 = 55565 4 7%?4O#D2,#$%+#"!"#$,)"'&'$2,-#,+*6)(+#v)*#.&$%#v*)?
$* 5 $ ) = ( K ] α )$ * = 55555555555 β+K $- = β $) $ * = ( β + K )$ ) α β β = 555555555555 α = 555555555555 K]α β+K P, +,# =#$%+,3)6#726$)L+# = 555555 ! MG#3] #)$#,223#$+3*+,)$/,+ 0 $- = α $*
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367
368 Chapter 6 Bipolar Junction Transistors (BJTs)
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6.2 Current–Voltage Characteristics
369
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(b)
Figure 6.18 [),L+5'&L")6#+V/&7)6+"$5(&,(/&$#320+6'#2@#)"#!"!#;<=#2*+,)$&"L#&"#$%+#)($&7+#320+#&"#$%+# (2332"5+3&$$+,#(2"@&L/,)$&2"#.&$%#$%+#2/$*/$#,+'&'$)"(+#(%#&"(6/0+0?
6.2.4 An Alternative Form of the Common-Emitter Characteristics @),*+&$#)*&(.$,4*:,21,$A7#$00();,&"$,*)0(0&2#,/2''2)%$'(&&$#,/"*#*/&$#(0&(/0,(0,(++30*&$-,() L(;<,X#.+#%)7+#&0+"$&@&+0#)#*),$&(/6),#*2&"$#l?#b2$+#$%)$#$%&'#2*+,)$&"L#*2&"$#@2,#$%+#$,)"'&'$2, &'#(%),)($+,&h+0#91#)#9)'+#(/,,+"$# . ) - #)#(266+($2,#(/,,+"$# .- - #)"0#)#(266+($2,Q+3&$$+,#726$)L+#+-* ? =%+#,)$&2# . - ⁄ . ) #&'#$%+#$,)"'&'$2,#β?#\2.+7+,-#$%+,+#&'#)"2$%+,#.)1#$2#3+)'/,+#β 8#(%)"L+#$%+#9)'+ (/,,+"$#91#)"#&"(,+3+"$# ∆$ ) #)"0#3+)'/,+#$%+#,+'/6$&"L#&"(,+3+"$# ∆$ - - #.%&6+#U++*&"L# +-* #(2"5 '$)"$?#=%&'#&'#&66/'$,)$+0#&"#D&L?#W?Ka:9>?#=%+#,)$&2# ∆$ - ⁄ ∆$ ) #'%2/60-#)((2,0&"L#$2#2/,#'$/01#$%/'#@),1&+60#)"#&0+"$&()6#7)6/+#@2,#β?#!$#$/,"'#2/$-#%2.+7+,-#$%)$#$%+#6)$$+,#7)6/+#2@#β#:()66+0#$!E(4I4!?'&2,#)(-#β >#&'#)#6&$$6+#0&@@+,+"$#@,23#$%+#0(#β :&?+?-# . - ⁄ . ) >?#C/(%#)#0&'$&"($&2"-#%2.+7+,-#&'#$22#'/9$6+ @2,#2/,#"++0'#&"#$%&'#922U?#Y+#'%)66#/'+#β $2#0+"2$+#92$%#0(#)"0#&"(,+3+"$)6#7)6/+'?KP The Saturation Voltage VCEsat and Saturation Resistance RCEsat J+@+,# "+T$# $2# $%+ +T*)"0+0#7&+.#2@#$%+#(2332"5+3&$$+,#(%),)($+,&'$&('#&"#$%+#')$/,)$&2"#,+L&2"#'%2."#&"#D&L? W?Ka:(>?#=%+#R9/"(%&"L#$2L+$%+,S#2@##$%+#(/,7+'##&"#$%+#')$/,)$&2"#,+L&2"#&3*6&+'#$%)$#$%+#&"5 (,+3+"$)6#β#&'#62.+,#$%+,+#$%)"#&"#$%+#)($&7+#,+L&2"?#I#*2''&96+#2*+,)$&"L#*2&"$#&"#$%+#')$/5 ,)$&2"#,+L&2"#&'#$%)$#6)9+6+0#m?#!$#&'#(%),)($+,&h+0#91#)#9)'+#(/,,+"$#.)-#)#(266+($2,#(/,,+"$ .-')$-#)"0#)#(266+($2,Q+3&$$+,#726$)L+#+-*')$?##D,23#2/,#*,+7&2/'#0&'(/''&2"#2@#')$/,)$&2"-#,+()66 $%)$#.-')$#`#β @2,(+0#.)-#.%+,+#β @2,(+0#i#β? !"$,$-− v-*,/3#.$0,(),0*&3#*&(2),*#$,#*&"$#,0&$$75,()-(/*&();,&"*&,&"$,0*&3#*&$-,*)0(0&2# $A"(9(&0,*,+24,/2++$/&2#%&2%$'(&&$#,#$0(0&*)/$,>-*0*&5
∂v
-* > -*')$ ≡ 5555555555 ∂$-
$) = .) $ - = . -')$
TX
=1*&()661-#>-*')$#,)"L+'#@,23#)#@+.#2%3'#$2#)#@+.#$+"'#2@#2%3'? A)"/@)($/,+,'#2@#9&*26),#$,)"'&'$2,'#/'+#DS*#$2#0+"2$+#$%+#0(#7)6/+#2@#β )"0#DG4#$2#0+"2$+#$%+#&"(,+3+"5 $)6# β?#=%+'+#'13926'#(23+#@,23#$%+#D5*),)3+$+,#0+'(,&*$&2"#2@#$.25*2,$#"+$.2,U'#:'++#I**+"0&T#F>.&$%#$%+#'/9'(,&*$#S:GT#0+"2$&"L#@2,.),0#)"0#*:4>#0+"2$&"L#(2332"#+3&$$+,? KP
6.2 Current–Voltage Characteristics
iC Saturation region
iC
Active region iB = IB1 .
..
iB = IB2 .
..
∆iC
iB = IB + ∆iB
IB vCE
IC
iB = IB
Q
iB
iB = . . . 0
VCE iB = 0
(a)
vCE
(b)
iB " IB bIB Slope " ICsat
1 RCEsat
X
VCEsat (c) Figure 6.19 F2332"5+3&$$+,#(%),)($+,&'$&('?#:'>#;)'&(#FE#(&,(/&$H#"2$+#$%)$#&"#:&>##$%+#%2,&h2"$)6#'()6+#&' +T*)"0+0#),2/"0#$%+#2,&L&"#$2#'%2.#$%+#')$/,)$&2"#,+L&2"#&"#'23+#0+$)&6?#I#3/(%#L,+)$+,#+T*)"'&2"#2@#$%+ ')$/,)$&2"#,+L&2"#&'#'%2."#&"#:)>?
!"*&, &"$, /2++$/&2#%&2%$'(&&$#, #$0(0&*)/$, 21, *, 0*&3#*&$-, BC!, (0, 0'*++, 0"23+-, "*.$, 9$$) *)&(/(7*&$-,1#2',&"$,1*/&,&"*&,9$&4$$),6,*)-,M,4$,)24,"*.$,&42,12#4*#-%/2)-3/&();,-(2-$0 (),0$#($0??,T0$$,*+02,L(;<,X
KK
!"#$%+#(2,,+'*2"0&"L#320+#2@#2*+,)$&2"#@2,#$%+#ABCDE=-#$%+#$,&20+#,+L&2"-#$%+#,+'&'$)"(+#9+$.++" 0,)&"#)"0#'2/,(+#&'#'3)66#9+()/'+#&$#&'#$%+#,+'&'$)"(+#2@#$%+#(2"$&"/2/'#:"2"5*&"(%+052@@>#(%)""+6?
375
376 Chapter 6 Bipolar Junction Transistors (BJTs) I#'&3*6+#320+6#@2,#$%+#')$/,)$+0#;<=#&'#'%2."#&"#D&L?#W?MP?#\+,+# + )* #&'#)''/3+0#(2"5 '$)"$#:)**,2T&3)$+61#P?d#]>#)"0# + -* #)6'2#&'#)''/3+0#(2"'$)"$-# + -*')$ ! P?M #]?#=%)$#&'-#.+ %)7+#"+L6+($+0#$%+#'3)66#')$/,)$&2"#,+'&'$)"(+# > -*')$ #@2,#$%+#')U+#2@#3)U&"L#$%+#320+6#'&35 *6+#@2,#%)"0#()6(/6)$&2"'?######### ICsat
IB B
$
$
VBE
0.7 V
%
0.2 V
VCEsat % Figure 6.20 I#'&3*6&@&+0#+V/&7)6+"$5(&,(/&$# 320+6#2@#$%+#')$/,)$+0#$,)"'&'$2,?
E
Example 6.3 D2,#$%+#(&,(/&$#&"#D&L?#W?MK-#&$#&'#,+V/&,+0#$2#0+$+,3&"+#$%+#7)6/+#2@#$%+#726$)L+# +)) #$%)$#,+'/6$'#&"#$%+#$,)"5 '&'$2,#2*+,)$&"L :)>#&"#$%+#)($&7+#320+#.&$%# + -* d G #]# :9>#)$#$%+#+0L+#2@#')$/,)$&2" :(>#0++*#&"#')$/,)$&2"#.&$%# β @2,(+0 d KP # D2,#'&3*6&(&$1-#)''/3+#$%)$# + )* #,+3)&"'#(2"'$)"$#)$#P?d#]?#=%+#$,)"'&'$2,#β#&'#'*+(&@&+0#$2#9+#GP? VCC " 10V VBB IC RB " 10 k&
RC " 1 k&
IB $ $
VCE
VBE %
%
Figure 6.21 F&,(/&$#@2,#ET)3*6+#W?N?
Solution :)>#=2#2*+,)$+#&"#$%+#)($&7+#320+#.&$%# + -* d G #]+ -- ] + -* 5 . - d 5555555555555555555555555 >KP ] G d 555555555555555 d G #3I K#UΩ
6.2 Current–Voltage Characteristics
. G . ) d 5555- d 555555 d P?K #3I β GP b2.#$%+#,+V/&,+0#7)6/+#2@# + )) #()"#9+#@2/"0#)'#@2662.'8 + )) d . ) > ) e + )* d P?K × KP e P?d d K?d#]
:9>#B*+,)$&2"#)$#$%+#+0L+#2@#')$/,)$&2"#&'#29$)&"+0#.&$%# + -* d P?N #]?#=%/' KP ] P?N . - d 5555555555555555555 d a?d ,'@ K C&"(+-#)$#$%+#+0L+#2@#')$/,)$&2"-# . - #)"0# . ) #),+#'$&66#,+6)$+0#91#βa?d . ) d 5555555 d P?Kae ,'@ GP =%+#,+V/&,+0#7)6/+#2@# +)) #()"#9+#0+$+,3&"+0#)' +)) d P?Kae × KP e P?d d M?We,_ :(>#=2#2*+,)$+#0++*#&"#')$/,)$&2"-# + -* d + -*')$ ! P?M ,_ =%/'KP ] P?M , . - d 5555555555555555555 d a?f ,'@ K Y+#$%+"#/'+#$%+#7)6/+#2@#@2,(+0 β#$2#0+$+,3&"+#$%+#,+V/&,+0#7)6/+#2@# . ) #)' .5 d a?f 5555555 d P?af ,'@ . ) d 5555555555555 β @2,(+0 KP )"0#$%+#,+V/&,+0# +)) #()"#"2.#9+#@2/"0#)' +)) d P?af × KP e P?d d KP?G ,_ B9'+,7+#$%)$#2"(+#$%+#$,)"'&'$2,#&'#&"#')$/,)$&2"-#&"(,+)'&"L#+)) #)"0#$%/'# . ) #,+'/6$'#&"#"+L6&L&96+#(%)"L+#&" . - #'&"(+# + -*')$ #.&66#(%)"L+#2"61#'6&L%$61?#=%/'# . - #&'#')&0#$28B'?U('?4-#.%&(%#&'#$%+#2,&L&"#2@#$%+#")3+ R')$/,)$&2"#320+#2@#2*+,)$&2"?S
EXERCISES 6.19 J+*+)$#ET)3*6+#W?N#@2,# > - d KP#U Ω? Ans. P?f#]H#P?fae#]H#K?Wf#] 6.20 D2,#$%+#(&,(/&$#&"#D&L?#W?MK-#@&"0# + -* #@2,# +)) d P ]? Ans. c#KP#] 6.21 D2,#$%+#(&,(/&$#&"#D&L?#W?MK-#6+$# +)) #9+#'+$#$2#$%+#7)6/+#29$)&"+0#&"#ET)3*6+#W?N-#*),$#:)>-#")3+61+)) d K?d #]?#]+,&@1#$%)$#$%+#$,)"'&'$2,#&'#&"0++0#2*+,)$&"L#&"#$%+#)($&7+#320+?#b2.-#.%&6+#U++*&"L +)) #(2"'$)"$-#@&"0#$%)$#7)6/+#$2#.%&(%# > - #'%2/60#9+#&"(,+)'+0#&"#2,0+,#$2#29$)&"#:)>#2*+,)$&2"#)$ $%+#+0L+#2@#')$/,)$&2"-#)"0#:9>#2*+,)$&2"#0++*#&"#')$/,)$&2"#.&$%# β @2,(+0 d KP? Ans. :)>#K?ae#U ΩH #:9>#a?f#U Ω
377
378 Chapter 6 Bipolar Junction Transistors (BJTs)
6.3 BJT Circuits at DC W$, *#$, )24, #$*-:, &2, /2)0(-$#, &"$, *)*+:0(0, 21, BC!, /(#/3(&0, &2, 4"(/", 2)+:, -/, .2+&*;$0, *#$ *77+($-<,=),&"$,12++24();,$A*'7+$0,4$,4(++,30$,&"$,0('7+$,'2-$+,(),4"(/", + )* 21,*,/2)% -3/&();,*)0(0&2#,(0,O();, *, /(#/3(&, &"$, 1(#0&, S3$0&(2), &"*&, 2)$, '30&, *)04$#, (0Y, .! AD$ED8 I%548 $B8 ?D48 ?('!B$B?%(8 %"4('?$!Cf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`, &"*&, (05, (0, v-), 21, *), !"!, *)0(0&2#, ;#$*&$#, &"*) −O<8 _,T2#,v-),21,*,"!",*)0(0&2#,+24$#,&"*),O<8,_Vf,=1,&"$,*)04$#,(0,:$05,&"$),23#,&*0G,(0 /2'7+$&$<,=1,&"$,*)04$#,(0,)25,*003'$,0*&3#*&(2)%'2-$,27$#*&(2)5,*)-,7#2/$$-,&2,-$&$#'()$ /3##$)&0,*)-,.2+&*;$0,*)-,&"$),&2,/"$/G,12#,/2)0(0&$)/:,21,&"$,#$03+&0,4(&",&"$,*003'7&(2),21 0*&3#*&(2)%'2-$,27$#*&(2)<,R$#$,&"$,&$0&,(0,303*++:,&2,/2'73&$,&"$,#*&(2, . - ⁄ . ) ,*)-,&2,.$#(1: &"*&,(&,(0,+24$#,&"*),&"$,*)0(0&2#,β,T(<$<5,β12#/$-,i,β V<,K()/$,β,12#,*,;(.$),*)0(0&2#,&:7$,.*#($0 2.$#,*,4(-$,#*);$5?P,2)$,'30&,30$,&"$,+24$0&,07$/(1($-, β,12#,&"(0,&$0&<,L()*++:5,)2&$,&"*&,&"$ 2#-$#,21,&"$0$,&42,*003'7&(2)0,/*),9$,#$.$#0$-<,@0,*,13#&"$#,*(-,&2,&"$,#$*-$#5,4$,7#2.(-$,() !*9+$,X<\,*,03''*#:,21,&"$,/2)-(&(2)0,*)-,'2-$+0,12#,&"$,27$#*&(2),21,&"$,BC!,(),(&0,&"#$$ 7200(9+$,'2-$0<
KM
=%)$#&'-#&@#2"+#9/1'#;<='#2@#)#(+,$)&"#*),$#"/39+,-#$%+#3)"/@)($/,+,#L/),)"$++'#2"61#$%)$#$%+&,#7)6/+' 2@#β @)66#.&$%&"#)#(+,$)&"#,)"L+-#')1#GP#$2#KGP?
+,#"-,#($. !#"$%/0)1,)-%#+,*'.#"$%/0)1,)-%#+,*'-
&'#()* !#"$%/0)1,)-%#+,*'.#"$%&'(')*'%#+,*'-
!"#$%% !"#$%&'(')*'%#+,*'.#"$%&'(')*'%#+,*'-
!
!
"
VBE ! 0.7 V
B
IB > 0
"
!
IB > 0 !
VBE ! 0.7 V
B
"
VBE < 0.5 V
B !
IB # O !
IB
E
VBC ! 0.5 V
E
bIB
VBC < 0.4 V
E
IC # O
C
C
C
"
VCEsat ! 0.2 V
!
" I #b C forced IB
"
VCE > 0.3 V
!
" I # bI C B
"
"
VCE
IC !
VBC < 0.4 V
"
! ! VBE
" VBC
!"!
Table 6.3 Conditions and Models for the Operation of the BJT in Various Modes
IB # O
"
"
E
bIB
C
"
B
IB > 0 "
! IC = bforcedIB
C
"
!
C
VEC > 0.3 V
!
IC # O
! IC # bIB
!
"
"
VCB ! 0.5 V
E
VCB < 0.4 V
E
VCB < 0.4 V
!
IC
VEC
!
VECsat ! 0.2 V
IB > 0 "
"
" " VCB
!
VEB ! 0.7 V
!
B
VEB ! 0.7 V
!
B
VEB < 0.5 V
!
IB
VEB
"!"
6.3 BJT Circuits at DC
379
380 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.4 62)0(-$#,&"$,/(#/3(&,0"24),(),L(;<,X$ &"(0, /(#/3(&, &2, -$&$#'()$, *++, )2-$, .2+&*;$0, *)-, 9#*)/", /3##$)&0<, W$, 4(++, *003'$, &"*&, β, (0, 07$/(1($-, &2 9$ ?OO< $10 V
IC
RC " 4.7 k&
RC " 4.7 k&
$4 V VC IB
10 V
VE 4V
IE
RE " 3.3 k&
RE " 3.3 k&
(b)
(a) $10 V
3
0.99 ) 1 " 0.99 mA 4.7 k& 10 % 0.99 ) 4.7
$4 V
5
5.3 V
4
1.00 % 0.99 " 0.01 mA 4 % 0.7 " 3.3 V 3.3 k&
3.3 " 1 mA 3.3
1
2
(c) Figure 6.22 I")61'&'#2@#$%+#(&,(/&$#@2,#ET)3*6+#W?e8#;'<#(&,(/&$H#;&<#(&,(/&$#,+0,)."#$2#,+3&"0#$%+#,+)0+,#2@#$%+#(2"5 7+"$&2"#/'+0#&"#$%&'#922U#$2#'%2.#(2""+($&2"'#$2#$%+#*2.+,#'/**61H#;)<#)")61'&'#.&$%#$%+#'$+*'#"/39+,+0?
Solution n6)"(&"L#)$#$%+#(&,(/&$#&"#D&L?#W?MM:)>-#.+#"2$+#$%)$#$%+#9)'+#&'#(2""+($+0#$2#+e#]#)"0#$%+#+3&$$+,#&'#(2"5 "+($+0#$2#L,2/"0#$%,2/L%#)#,+'&'$)"(+#>*?#=%+,+@2,+-#&$#&'#')@+#$2#(2"(6/0+#$%)$#$%+#9)'+Q+3&$$+,#4/"($&2"
6.3 BJT Circuits at DC
.&66#9+#@2,.),0#9&)'+0?#I''/3&"L#$%)$#$%&'#&'#$%+#()'+#)"0#)''/3&"L#$%)$#+)*#&'#)**,2T&3)$+61#P?d#]-#&$#@265 62.'#$%)$#$%+#+3&$$+,#726$)L+#.&66#9+# + * = e ] + )* #! e ] P?d = N?N#] Y+#),+#"2.#&"#)"#2**2,$/"+#*2'&$&2"H#.+#U"2.#$%+#726$)L+'#)$#$%+#$.2#+"0'#2@#>*#)"0#$%/'#()"#0+$+,3&"+ $%+#(/,,+"$#.*#$%,2/L%#&$+* ] P N?N 5 = 5555555 = K#3I . * = 55555555555555 >* N?N C&"(+#$%+#(266+($2,#&'#(2""+($+0#$%,2/L%#>-#$2#$%+#+KP5]#*2.+,#'/**61-#&$#)**+),'#*2''&96+#$%)$#$%+#(266+(5 $2,#726$)L+#.&66#9+#%&L%+,#$%)"#$%+#9)'+#726$)L+-#.%&(%#&3*6&+'#)($&7+5320+#2*+,)$&2"?#I''/3&"L#$%)$#$%&' &'#$%+#()'+-#.+#()"#+7)6/)$+#$%+#(266+($2,#(/,,+"$#@,23 .- = α .* =%+#7)6/+#2@#α#&'#29$)&"+0#@,23
β KPP α = 555555555555 = 555555555 #!#P?aa β+K KPK =%/'#.-#.&66#9+#L&7+"#91 . - = P?aa × K = P?aa#3I Y+#),+#"2.#&"#)#*2'&$&2"#$2#/'+#B%3k'#6).#$2#0+$+,3&"+#$%+#(266+($2,#726$)L+#+- -# + - = KP ] . - > - = KP ] P?aa × e?d#! +G?N#] C&"(+# $%+# 9)'+# &'# )$# +e# ]-# $%+# (266+($2,Q9)'+# 4/"($&2"# &'# ,+7+,'+# 9&)'+0# 91# K?N# ]-# )"0# $%+# $,)"'&'$2,# &' &"0++0#&"#$%+#)($&7+#320+#)'#)''/3+0? !$#,+3)&"'#2"61#$2#0+$+,3&"+#$%+#9)'+#(/,,+"$#.)-#)'#@2662.'8 .* K5 5 = 55555555 . ) = 55555555555 #!#P?PK#3I β+K KPK ;+@2,+#6+)7&"L#$%&'#+T)3*6+#.+#.&'%#$2#+3*%)'&h+#'$,2"L61#$%+#7)6/+#2@#(),,1&"L#2/$#$%+#)")61'&' 0&,+($61#2"#$%+#(&,(/&$#0&)L,)3?#B"61#&"#$%&'#.)1#.&66#2"+#9+#)96+#$2#)")61h+#(23*6+T#(&,(/&$'#&"#)#,+)'2"5 )96+#6+"L$%#2@#$&3+?#D&L/,+#W?MM:(>#&66/'$,)$+'#$%+#)927+#)")61'&'#2"#$%+#(&,(/&$#0&)L,)3-#.&$%#$%+#2,0+,#2@ $%+#)")61'&'#'$+*'#&"0&()$+0#91#$%+#(&,(6+0#"/39+,'?#
381
382 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.5 Y+#.&'%#$2#)")61h+#$%+#(&,(/&$#2@#D&L?#W?MN:)>#$2#0+$+,3&"+#$%+#726$)L+'#)$#)66#"20+'#)"0#$%+#(/,,+"$' $%,2/L%#)66#9,)"(%+'?#b2$+#$%)$#$%&'#(&,(/&$#&'#&0+"$&()6#$2#$%)$#2@#D&L?#W?MM#+T(+*$#$%)$#$%+#726$)L+#)$ $%+#9)'+#&'#"2.#+W#]?#I''/3+#$%)$#$%+#$,)"'&'$2,# β#&'#'*+(&@&+0#$2#9+#'?8&4'B?#GP? $10 V
$10 V 3
1.6 mA 4.7 k&
4.7 k&
10 % 1.6 ) 4.7 " 2.48 Impossible, not in active mode
$6 V
$6 V
6 % 0.7 " $5.3 V 3.3 k&
3.3 k&
5.3 " 1.6 mA 3.3
4
1
2
(b)
(a)
(c) Figure 6.23 I")61'&'#2@#$%+#(&,(/&$#@2,#ET)3*6+#W?G?#b2$+#$%)$#$%+#(&,(6+0#"/39+,'#&"0&()$+#$%+#2,0+,#2@ $%+#)")615 '&'#'$+*'?
6.3 BJT Circuits at DC
Solution Y&$%#cW#]#)$#$%+#9)'+-#$%+#9)'+Q+3&$$+,#4/"($&2"#.&66#9+#@2,.),0#9&)'+0H#$%/'+ * = + W ] + )* #!#W ] P?d = G?N#] )"0 G?N . * = 5555555 = K?W#3I N?N b2.-#)''/3&"L#)($&7+5320+#2*+,)$&2"-#.-#`#α.*8!#.*H#$%/'+ - = +KP ] e?d × . - #!#KP ] d?GM = M?ef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aW#3I e?d *)-,.),/*),)24,9$,123)-,*0 . ) = . * ] . - = K?W ] P?aW = P?We#3I !"30,&"$,*)0(0&2#,(0,27$#*&();,*&,*,12#/$-,β,21 . P?aW β @2,(+0 = 5555- = 5555555555 = K?G .)
P?We
K()/$,β12#/$-,(0,+$00,&"*),&"$,I$!$IUI,07$/(1($-,.*+3$,21,β5,&"$,*)0(0&2#,(0,()-$$-,0*&3#*&$-<,W$,0"23+$'7"*0(>$, "$#$, &"*&, (), &$0&();, 12#, 0*&3#*&(2), &"$, '()('3', .*+3$, 21, β, 0"23+-, 9$, 30$-<, B:, &"$, 0*'$ &2G$)5,(1,4$,*#$,-$0(;)();,*,/(#/3(&,(),4"(/",*,*)0(0&2#,(0,&2,9$,0*&3#*&$-5,&"$,-$0(;),0"23+-,9$,9*0$2),&"$,'()('3',07$/(1($-,β<,J9.(230+:5,(1,*,*)0(0&2#,4(&",&"(0,'()('3',β,(0,0*&3#*&$-5,&"$),*)0(0&2#0 4(&","(;"$#,.*+3$0,21,β,4(++,*+02,9$,0*&3#*&$-<,!"$,-$&*(+0,21,&"$,*)*+:0(0,*#$,0"24),(),L(;<,X
383
384 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.6 Y+# .&'%# $2# )")61h+# $%+# (&,(/&$# &"# D&L?# W?Me:)># $2# 0+$+,3&"+# $%+# 726$)L+'# )$# )66# "20+'# )"0# $%+# (/,,+"$' $%,2/L%#)66#9,)"(%+'?#b2$+#$%)$#$%&'#(&,(/&$#&'#&0+"$&()6#$2#$%)$#(2"'&0+,+0#&"#ET)3*6+'#W?e#)"0#W?G#+T(+*$ $%)$#"2.#$%+#9)'+#726$)L+#&'#h+,2?
2 1
(a)
(b)
Figure 6.24 ET)3*6+#W?W8#;'<#(&,(/&$H#;&<#)")61'&'-#.&$%#$%+#2,0+,#2@#$%+#)")61'&'#'$+*'#&"0&()$+0#91#(&,(6+0#"/39+,'?
Solution C&"(+#$%+#9)'+#&'#)$#h+,2#726$'#)"0#$%+#+3&$$+,#&'#(2""+($+0#$2#L,2/"0#$%,2/L%#>*-#$%+#9)'+Q+3&$$+,#4/"($&2"#()"5 "2$#(2"0/($#)"0#$%+#+3&$$+,#(/,,+"$#&'#h+,2?#b2$+#$%)$#$%&'#'&$/)$&2"#.&66#29$)&"#)'#62"L#)'#$%+#726$)L+#)$#$%+#9)'+#&' 6+''#$%)"#P?G#]#2,#'2?#I6'2-#$%+#(266+($2,Q9)'+#4/"($&2"#()""2$#(2"0/($-#'&"(+#$%+#!5$1*+#(266+($2,#&'#(2""+($+0 $%,2/L%#>-#$2#$%+#*2'&$&7+#*2.+,#'/**61#.%&6+#$%+#"5$1*+#9)'+#&'#)$#L,2/"0?#!$#@2662.'#$%)$#$%+#(266+($2,#(/,,+"$ .&66#9+#h+,2?#=%+#9)'+#(/,,+"$#.&66#)6'2#%)7+#$2#9+#h+,2-#)"0#$%+#$,)"'&'$2,#&'#&"#$%+#EU?%GG#320+#2@#2*+,)$&2"? =%+#+3&$$+,#726$)L+#.&66#9+#h+,2-#.%&6+#$%+#(266+($2,#726$)L+#.&66#9+#+V/)6#$2#+KP ]-#'&"(+#$%+#726$)L+ 0,2*'#)(,2''#>*#)"0#>-#),+#h+,2?#D&L/,+#W?Me:9>#'%2.'#$%+#)")61'&'#0+$)&6'? ,,,,,,,,,,
EXERCISES D6.22 D2,#$%+#(&,(/&$#&"#D&L?#W?MM:)>-#@&"0#$%+#%&L%+'$#726$)L+#$2#.%&(%#$%+#9)'+#()"#9+#,)&'+0#.%&6+#$%+ $,)"'&'$2,#,+3)&"'#&"#$%+#)($&7+#320+?#I''/3+#α#!#K? Ans. +e?d#] D6.23 J+0+'&L"#$%+#(&,(/&$#2@#D&L?#W?MM:)>#:&?+?-#@&"0#"+.#7)6/+'#@2,#>*#)"0#>->#$2#+'$)96&'%#)#(266+($2, (/,,+"$#2@#P?G#3I#)"0#)#,+7+,'+59&)'#726$)L+#2"#$%+#(266+($2,Q9)'+#4/"($&2"#2@#M#]?#I''/3+#α#!#K? Ans. >*#=#W?W#UΩH#>-#=#f#UΩ 6.24 D2,#$%+#(&,(/&$#&"#D&L?#W?MN:)>-#@&"0#$%+#7)6/+#$2#.%&(%#$%+#9)'+#726$)L+#'%2/60#9+#(%)"L+0#'2#$%)$ $%+#$,)"'&'$2,#2*+,)$+'#&"#')$/,)$&2"#.&$%#)#@2,(+0#β#2@#G? Ans. +^
6.3 BJT Circuits at DC
385
Example 6.7 Y+# .)"$# $2# )")61h+# $%+# (&,(/&$# 2@# D&L?# W?MG:)># $2# 0+$+,3&"+# $%+# 726$)L+'# )$# )66# "20+'# )"0# $%+# (/,,+"$' $%,2/L%#)66#9,)"(%+'? V $ " $10 V
$10 V 10 % 0.7 " 4.65 mA 2
2 k&
RE " 2 k&
$0.7 V 5
2
1
0.05 mA
%10 $ 4.6 ) 1 " %5.4 V RC " 1 k&
4
1 k& 3
0.99 ) 4.65
V % " %10 V
4.6 mA %10 V
(a)
(b)
Figure 6.25 ET)3*6+#W?d8#;'<#(&,(/&$H#;&<#)")61'&'-#.&$%#$%+#'$+*'#&"0&()$+0#91#(&,(6+0#"/39+,'?
Solution =%+#9)'+#2@#$%&'#"!"#$,)"'&'$2,#&'#L,2/"0+0-#.%&6+#$%+#+3&$$+,#&'#(2""+($+0#$2#)#*2'&$&7+#'/**61#:+ +#=#+KP#]> $%,2/L%#>*?#!$#@2662.'#$%)$#$%+#+3&$$+,Q9)'+#4/"($&2"#.&66#9+#@2,.),0#9&)'+0#.&$% + * = + *) #!#P?d#] =%/'#$%+#+3&$$+,#(/,,+"$#.&66#9+#L&7+"#91# +
+ ]+ KP ] P?d . * = 55555555555555555*5 = 5555555555555555555 = e?WG#3I M >* K()/$,&"$,/2++$/&2#,(0,/2))$/&$-,&2,*,)$;*&(.$,0377+:,T'2#$,)$;*&(.$,&"*),&"$,9*0$,.2+&*;$V,&"#23;",>-5,(& (0,"%BB$#&4,&"*&,&"(0,*)0(0&2#,(0,27$#*&();,(),&"$,*/&(.$,'2-$<,@003'();,&"(0,&2,9$,&"$,/*0$5,4$,29&*() .- = α .* K()/$,)2,.*+3$,12#,β "*0,9$$),;(.$)5,4$,0"*++,*003'$,β,=,?OO5,4"(/",#$03+&0,(),α,=,O
+- = + + .- >= # −KP + e?W × K = ] G?e#]
386 Chapter 6 Bipolar Junction Transistors (BJTs) ,,,
=%/'# $%+# (266+($2,Q9)'+# 4/"($&2"# &'# ,+7+,'+# 9&)'+0# 91# G?e# ]-# )"0# $%+# $,)"'&'$2,# &'# &"0++0# &"# $%+# )($&7+ 320+-#.%&(%#'/**2,$'#2/,#2,&L&")6#)''/3*$&2"? !$#,+3)&"'#2"61#$2#()6(/6)$+#$%+#9)'+#(/,,+"$.* 5 = e?WG 5555555555 #!#P?PG#3I . ) = 55555555555 β+K KPK B97&2/'61-#$%+#7)6/+#2@#β#(,&$&()661#)@@+($'#$%+#9)'+#(/,,+"$?#b2$+-#%2.+7+,-#$%)$#&"#$%&'#(&,(/&$#$%+#7)6/+#2@#β .&66#%)7+#"2#+@@+($#2"#$%+#320+#2@#2*+,)$&2"#2@#$%+#$,)"'&'$2,?#C&"(+#β#&'#L+"+,)661#)"#&665'*+(&@&+0#*),)3+$+,$%&'#(&,(/&$#,+*,+'+"$'#)#L220#0+'&L"?#I'#)#,/6+-#2"+#'%2/60#'$,&7+#$2#54B$C!8?D48E$(EU$?8BUED8?D'?8$?B8"4(G%(M I'!E48$B8'B8$!B4!B$?$F48?%8?D48F'&U48%G8β8'B8"%BB$#&4@#=%+#)")61'&'#0+$)&6'#),+#&66/'$,)$+0#&"#D&L?#W?MG:9>?
EmIAO[E#G?d EXERCISES D6.25#D2,#$%+#(&,(/&$#&"#D&L?#W?MG:)>-#@&"0#$%+#6),L+'$#7)6/+#$2#.%&(%#>-#()"#9+#,)&'+0#.%&6+#$%+#$,)"'&'$2, ,+3)&"'#&"#$%+#)($&7+#320+? Ans. M?MW#UΩ D6.26 J+0+'&L"#$%+#(&,(/&$#2@#D&L?#W?MG:)>#:&?+?-#@&"0#"+.#7)6/+'#@2,#>*#)"0#>->#$2#+'$)96&'%#)#(266+($2, (/,,+"$#2@#K#3I#)"0#)#,+7+,'+#9&)'#2"#$%+#(266+($2,Q9)'+#4/"($&2"#2@#e#]?#I''/3+#α#!#K? Ans. >*#=#a?N#UΩH#>-#=#W#UΩ
Example 6.8 Y+#.)"$#$2#)")61h+#$%+#(&,(/&$#&"#D&L?#W?MW:)>#$2#0+$+,3&"+#$%+#726$)L+'#)$#)66#"20+'#)"0#$%+#(/,,+"$'#&"#)66 9,)"(%+'?#I''/3+#β# =#KPP?
(a)
(b)
Figure 6.26 ET)3*6+#W?f8#;'<#(&,(/&$H#;&<#)")61'&'-#.&$%#$%+#'$+*'#&"0&()$+0#91#$%+#(&,(6+0#"/39+,'?
6.3 BJT Circuits at DC
387
Solution =%+#9)'+Q+3&$$+,#4/"($&2"#&'#(6+),61#@2,.),0#9&)'+0?#=%/'+G ] + )* G ] P?d #!# 5555555555555555 = P?PeN#3I . ) = 555555555555555555555 >) KPP I''/3+#$%)$#$%+#$,)"'&'$2,#&'#2*+,)$&"L#&"#$%+#)($&7+#320+?#Y+#"2.#()"#.,&$+ . - = β . ) = KPP × P?PeN = e?N#3I =%+#(266+($2,#726$)L+#()"#"2.#9+#0+$+,3&"+0#)' + - = +KP ] . - > - = KP ] e?N × M = +K?e#] C&"(+#$%+#9)'+#726$)L+#+)#&'# + ) = + )* #!#+ P?d#] &$#@2662.'#$%)$#$%+#(266+($2,Q9)'+#4/"($&2"#&'#,+7+,'+59&)'+0#91#P?d#]#)"0#$%+#$,)"'&'$2,#&'#&"0++0#&"#$%+#)($&7+ 320+?#=%+#+3&$$+,#(/,,+"$#.&66#9+#L&7+"#91 . * = ( β + K ). ) = KPK × P?PeN#!#e?N#3I Y+#"2$+#@,23#$%&'#+T)3*6+#$%)$#$%+#(266+($2,#)"0#+3&$$+,#(/,,+"$'#0+*+"0#(,&$&()661#2"#$%+ 7)6/+#2@# β?#!" @)($-#&@#β#.+,+#KPo#%&L%+,-#$%+#$,)"'&'$2,#.2/60#6+)7+#$%+#)($&7+#320+#)"0#+"$+,#')$/,)$&2"?#=%+,+@2,+#$%&' (6+),61#&'#)##'5#0+'&L"?#=%+#)")61'&'#0+$)&6'#),+#&66/'$,)$+0#&"#D&L?#W?MW:9>?
EXERCISE D6.27 =%+#(&,(/&$#2@#D&L?#W?MW:)>#&'#$2#9+#@)9,&()$+0#/'&"L#)#$,)"'&'$2,#$1*+#.%2'+#β#&'#'*+(&@&+0#$2#9+ &"#$%+#,)"L+#2@#GP#$2#KGP?#=%)$#&'-#&"0&7&0/)6#/"&$'#2@#$%&'#')3+#$,)"'&'$2,#$1*+#()"#%)7+#β#7)6/+' )"1.%+,+# &"# $%&'# ,)"L+?# J+0+'&L"# $%+# (&,(/&$# 91# '+6+($&"L# )# "+.# 7)6/+# @2,# >-# '2# $%)$# )66 @)9,&()$+0# (&,(/&$'# ),+# L/),)"$++0# $2# 9+# &"# $%+# )($&7+# 320+?# Y%)$# &'# $%+# ,)"L+# 2@# (266+($2, 726$)L+'#$%)$#$%+#@)9,&()$+0#(&,(/&$'#3)1#+T%&9&$_ Ans. >-,=,?<^,GΩ`,+-,=,O<\,_,&2,X
388 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.9 Y+#.)"$#$2#)")61h+#$%+#(&,(/&$#2@#D&L?#W?Md#$2#0+$+,3&"+#$%+#726$)L+'#)$#)66#"20+'#)"0#$%+#(/,,+"$'#$%,2/L% )66#9,)"(%+'?#=%+#3&"&3/3#7)6/+#2@#β#&'#'*+(&@&+0#$2#9+#NP? $5 V $5 V 4 1 k&
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VB $ 0.5 % (%5) 10
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6
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(b)
Figure 6.27 ET)3*6+#W?a8#;'<#(&,(/&$H#;&<#)")61'&'#.&$%#'$+*'#"/39+,+0?
Solution I#V/&(U#L6)"(+#)$#$%&'#(&,(/&$#,+7+)6'#$%)$#$%+#$,)"'&'$2,#.&66#9+#+&$%+,#)($&7+#2,#')$/,)$+0?#I''/3&"L#)($&7+5 320+#2*+,)$&2"#)"0#"+L6+($&"L#$%+#9)'+#(/,,+"$-#.+#'++#$%)$#$%+#9)'+#726$)L+#.&66#9+#)**,2T&3)$+61#h+,2 726$'-#$%+#+3&$$+,#726$)L+#.&66#9+#)**,2T&3)$+61#+P?d#]-#)"0#$%+#+3&$$+,#(/,,+"$#.&66#9+#)**,2T&3)$+61#e?N 3I?#C&"(+#$%+#3)T&3/3#(/,,+"$#$%)$#$%+#(266+($2,#()"#'/**2,$#.%&6+#$%+#$,)"'&'$2,#,+3)&"'#&"#$%+#)($&7+ 320+#&'#)**,2T&3)$+61#P?G#3I-#&$#@2662.'#$%)$#$%+#$,)"'&'$2,#&'#0+@&"&$+61#')$/,)$+0? I''/3&"L# $%)$# $%+# $,)"'&'$2,# &'# ')$/,)$+0# )"0# 0+"2$&"L# $%+# 726$)L+# )$# $%+# 9)'+# 91# +)# :,+@+,# $2# D&L? W?Md9>-#&$#@2662.'#$%)$ + * = + ) + + *) #!#+ ) + P?d + - = + * ] + *-')$ #!#+ ) + P?d ] P?M = + ) + P?G +G ] + G ] + ) ] P?d . * = 555555555555555555*5 = 5555555555555555555555555555 = e?N ] + ) # 3I K K + . ) = 55555)5 = P?K+ ) # 3I KP +- Q ( ]G ) + ) + P?G + G 5 = 5555555555555555555555555555 5 = P?K+ ) + P?GG# 3I . - = 5555555555555555555555 KP KP
6.3 BJT Circuits at DC
c0();,&"$,#$+*&(2)0"(7,.*, =, .),+,.- 5,4$,29&*() e?N ] + ) = P?K+ ) + P?K+ ) + P?GG 4"(/",#$03+&0,() N?dG + ) = 5555555555 #!#N?KN#] K?M K390&(&3&();,(),&"$,$S3*&(2)0,*92.$5,4$,29&*() + * = N?fN#] + - = N?WN#] . * = K?Kd#3I . - = P?fW#3I . ) = P?NK#3I 1#2',4"(/",4$,0$$,&"*&,&"$,*)0(0&2#,(0,0*&3#*&$-5,0()/$,&"$,.*+3$,21,12#/$-,β,(0 P?fW β @2,(+0 = 5555555555 #!#M?f P?NK
.%&(%#&'#3/(%#'3)66+,#$%)"#$%+#'*+(&@&+0#3&"&3/3#β?
,,,,,,,,,,,
389
390 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.10 Y+#.)"$#$2#)")61h+#$%+#(&,(/&$#2@#D&L?#W?Mf:)>#$2#0+$+,3&"+#$%+#726$)L+'#)$#)66#"20+'#)"0#$%+#(/,,+"$'#$%,2/L% )66#9,)"(%+'?#I''/3+#β #=#KPP? $15 V
$15 V
RC " 5 k&
RB 1 " 100 k&
RC " 5 k&
VBB " $5 V RBB " 33.3 k&
IE
IB
RB 2 " 50 k&
RE " 3 k&
RE " 3 k&
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(b)
(a) $15 V
$15 V
1.28 mA 0.103 mA
5 k& $8.6 V
$5 V
100 k& 0.013 mA
33.3 k&
$4.57 V 0.013 mA
$3.87 V
$4.57 V 1.29 mA
50 k&
3 k&
(c)
0.09 mA
(d)
Figure 6.28 F&,(/&$'#@2,#ET)3*6+#W?KP?
Solution =%+#@&,'$#'$+*#&"#$%+#)")61'&'#(2"'&'$'#2@#'&3*6&@1&"L#$%+#9)'+#(&,(/&$#/'&"L#=%p7+"&"k'#$%+2,+3?#=%+#,+'/6$ &'#'%2."#&"#D&L?#W?Mf:9>-#.%+,+ > )M GP = KG 555555555555555555555 = +G#] + )) = +KG 55555555555555555555555 > )K + > )M KPP + GP
6.3 BJT Circuits at DC
> )) = > )K #qq#> )M = KPP#qq#GP = NN?N#UΩ =2#+7)6/)$+#$%+#9)'+#2,#$%+#+3&$$+,#(/,,+"$-#.+#%)7+#$2#.,&$+#)#622*#+V/)$&2"#),2/"0#$%+#622*#6)9+6+0#[#&" D&L?#W?Mf:9>?#b2$+-#%2.+7+,-#$%)$#$%+#(/,,+"$#$%,2/L%# >))#&'#0&@@+,+"$#@,23#$%+#(/,,+"$#$%,2/L%#>*?#=%+ 622*#+V/)$&2"#.&66#9+ + )) = . ) > )) + + )* + . * > * b2.-#)''/3&"L#)($&7+5320+#2*+,)$&2"-#.+#,+*6)(+#.)#.&$%# .* 5 . ) = 55555555555 β+K )"0#,+),,)"L+#$%+#+V/)$&2"#$2#29$)&" + )) ] + )* 5 . * = 55555555555555555555555555555555555555555555555 > * + [ > )) ⁄ ( β + K ) ] D2,#$%+#"/3+,&()6#7)6/+'#L&7+"#.+#%)7+ G ] P?d . * = 5555555555555555555555555555555555555 = K?Ma#3I N + ( NN?N ⁄ KPK ) =%+#9)'+#(/,,+"$#.&66#9+ K?Ma . ) = 5555555555 = P?PKMf#3I KPK =%+#9)'+#726$)L+#&'#L&7+"#91 + ) = + )* + . * > * = P?d + K?Ma × N = e?Gd#] W$,/*),$.*+3*&$,&"$,/2++$/&2#,/3##$)&,*0, . - = α . * = P?aa × K?Ma = K?Mf#3I =%+#(266+($2,#726$)L+#()"#"2.#9+#+7)6/)$+0#)'# + - = +KG ] . - > - = KG ] K?Mf × G = f?W#] !$#@2662.'#$%)$#$%+#(266+($2,#&'#%&L%+,#&"#*2$+"$&)6#$%)"#$%+#9)'+#91#e?PN#]-#.%&(%#3+)"'#$%)$#$%+ $,)"'&'$2, &'#&"#$%+#)($&7+#320+-#)'#%)0#9++"#)''/3+0?#=%+#,+'/6$'#2@#$%+#)")61'&'#),+#L&7+"#&"#D&L?#W?Mf:(-#0>?
EXERCISE 6.28 !@#$%+#$,)"'&'$2,#&"#$%+#(&,(/&$#2@#D&L?#W?Mf:)>#&'#,+*6)(+0#.&$%#)"2$%+,#%)7&"L#%)6@#$%+#7)6/+#2@#β :&?+?- β =#GP>-#@&"0#$%+#"+.#7)6/+#2@#.--#)"0#+T*,+''#$%+#(%)"L+#&"#.-#)'#)#*+,(+"$)L+? Ans. .-,=,?^,'@`,−?Oj
391
392 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.11 Y+# .)"$# $2# )")61h+# $%+# (&,(/&$# &"# D&L?# W?Ma:)># $2# 0+$+,3&"+# $%+# 726$)L+'# )$# )66# "20+'# )"0# $%+# (/,,+"$' $%,2/L%#)66#9,)"(%+'? $15 V
RE2 " 2 k&
RC1 " 5 k&
RB 1 " 100 k&
IE2
Q2 IC1
IB2
Q1
IC2 RC2 " 2.7 k&
RB 2 " 50 k&
RE " 3 k&
(a) $15 V 2.78 mA
1.252 mA
0.103 mA
100 k&
$9.44 V $8.74 V Q1
$4.57 V
2 k&
5 k& Q2 0.0275 mA 1.28 mA
$7.43 V
0.013 mA $3.87 V 50 k& 0.09 mA
2.7 k&
3 k& 1.29 mA
2.75 mA
(b) Figure 6.29 F&,(/&$'#@2,#ET)3*6+#W?KK?
Solution Y+#@&,'$#,+(2L"&h+#$%)$#*),$#2@#$%&'#(&,(/&$#&'#&0+"$&()6#$2#$%+#(&,(/&$#.+#)")61h+0#&"#ET)3*6+#W?KP g")3+61$%+# (&,(/&$# 2@# D&L?# W?Mf:)>?# =%+# 0&@@+,+"(+-# 2@# (2/,'+-# &'# $%)$# &"# $%+# "+.# (&,(/&$# .+# %)7+# )" )00&$&2")6
6.3 BJT Circuits at DC
$,)"'&'$2,#VM#$2L+$%+,#.&$%#&$'#)''2(&)$+0#,+'&'$2,'#>*M#)"0#>-M?#I''/3+#$%)$#VK#&'#'$&66#&"#$%+#)($&7+#320+? =%+#@2662.&"L#7)6/+'#.&66#9+#&0+"$&()6#$2#$%2'+#29$)&"+0#&"#$%+#*,+7&2/'#+T)3*6+8 +)?,=,+8<^N,_
,.*?,=,?
.)?,=,O
.-?,=,?
\2.+7+,-#$%+#(266+($2,#726$)L+#.&66#9+#0&@@+,+"$#$%)"#*,+7&2/'61#()6(/6)$+0-#'&"(+#*),$#2@#$%+#(266+($2,#(/,5 ,+"$#.-K#.&66#@62.#&"#$%+#9)'+#6+)0#2@#VM#:.)M>?#I'#)#@&,'$#)**,2T&3)$&2"#.+#3)1#)''/3+#$%)$#.)M#&'#3/(% '3)66+,# $%)"# .-KH# $%)$# &'-# .+# 3)1# )''/3+# $%)$# $%+# (/,,+"$# $%,2/L%# >-K# &'# )632'$# +V/)6# $2# .-K?# =%&'# .&66 +")96+#/'#$2#()6(/6)$+#+-K8 + -K #!#+KG ] . -K > -K = KG ] K?Mf × G = +f?W#] =%/'#VK#&'#&"#$%+#)($&7+#320+-#)'#%)0#9++"#)''/3+0? I'#@),#)'#VM#&'#(2"(+,"+0-#.+#"2$+#$%)$#&$'#+3&$$+,#&'#(2""+($+0#$2#+KG#]#$%,2/L%#>*M?#!$#&'#$%+,+@2,+ ')@+#$2#)''/3+#$%)$#$%+#+3&$$+,Q9)'+#4/"($&2"#2@#VM#.&66#9+#@2,.),0#9&)'+0?#=%/'#$%+#+3&$$+,#2@#VM#.&66#9+ )$#)#726$)L+#+*M#L&7+"#91# + *M = + -K + + *)
VM
#!#f?W + P?d = +a?N#]
=%+#+3&$$+,#(/,,+"$#2@#VM#3)1#"2.#9+#()6(/6)$+0#)'# +KG ] + *M KG ] a?N 5 = 5555555555555555555 = M?fG#3I . *M = 55555555555555555555555 M > *M K()/$, &"$, /2++$/&2#, 21, VP, (0, #$&3#)$-, &2, ;#23)-, .(*, >-P5,(&, (0, 7200(9+$, &"*&,VP, (0, 27$#*&();,(),&"$, */&(.$ '2-$<,@003'$,&"(0,&2,9$,&"$,/*0$<,W$,)24,1()-,.-P,*0, . -M = α M . *M = P?aa × M?fG = M?fM#3I
( )''/3&"L# β M = KPP )
=%+#(266+($2,#726$)L+#2@#VM#.&66#9+# + -M = . -M > -M = M?fM × M?d = d?WM#] .%&(%#&'#62.+,#$%)"#+)M#91#P?af#]?#=%/'#VM#&'#&"#$%+#)($&7+#320+-#)'#)''/3+0? !$# &'# &3*2,$)"$# )$# $%&'# '$)L+# $2# @&"0# $%+# 3)L"&$/0+# 2@# $%+# +,,2,# &"(/,,+0# &"# 2/,# ()6(/6)$&2"'# 91# $%+ )''/3*$&2"#$%)$#.)M#&'#"+L6&L&96+?#=%+#7)6/+#2@#.)M#&'#L&7+"#91 . *M M?fG = 5555555555 = P?PMf#3I . )M = 55555555555555 βM + K KPK 4"(/",(0,()-$$-,'3/",0'*++$#,&"*),.-?,T?-K = . -K ] . )M = K?Mf ] P?PMf = K?MGM#3I + -K = KG ] G × K?MGM = f?de#] + *M = f?de + P?d = a?ee#] KG ] a?ee . *M = 5555555555555555555555 = M?df#3I M
393
394 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.11 continued
. -M = P?aa × M?df = M?dG#3I + -M = M?dG × M?d = d?eN#] M?df . )M = 5555555555 = P?PMdG#3I KPK b2$+#$%)$#$%+#"+.#7)6/+#2@#.)M#&'#7+,1#(62'+#$2#$%+#7)6/+#/'+0#&"#2/,#&$+,)$&2"-#)"0#"2#@/,$%+,#&$+,)$&2"' ),+#.),,)"$+0?#=%+#@&")6#,+'/6$'#),+#&"0&()$+0#&"#D&L?#W?Ma:9>? =%+#,+)0+,#4/'$&@&)961#3&L%$#9+#.2"0+,&"L#)92/$#$%+#"+(+''&$1#@2,#/'&"L#)"#&$+,)$&7+#'(%+3+#&"#'2675 &"L#)#6&"+),#:2,#6&"+),&h+0>#*,296+3?#!"0++0-#.+#()"#29$)&"#$%+#+T)($#'26/$&2"#:&@#.+#()"#()66#)"1$%&"L#.+ ),+#02&"L#.&$%#)#@&,'$52,0+,#320+6#+T)($j>#91#.,&$&"L#)**,2*,&)$+#+V/)$&2"'?#=%+#,+)0+,#&'#+"(2/,)L+0#$2 @&"0#$%&'#'26/$&2"#)"0#$%+"#(23*),+#$%+#,+'/6$'#.&$%#$%2'+#29$)&"+0#)927+?#!$#&'#&3*2,$)"$#$2#+3*%)'&h+%2.+7+,-#$%)$#&"#32'$#'/(%#*,296+3'#&$#&'#V/&$+#'/@@&(&+"$#$2#29$)&"#)"#)**,2T&3)$+#'26/$&2"-#*,27&0+0#.+ ()"#29$)&"#&$#V/&(U61#)"0-#2@#(2/,'+-#(2,,+($61?
!"#$%+#)927+#+T)3*6+'-#.+#@,+V/+"$61#/'+0#)#*,+(&'+#7)6/+#2@# α $2#()6(/6)$+#$%+#(266+($2, (/,,+"$?#C&"(+# α#!#K-#$%+#+,,2,#&"#'/(%#()6(/6)$&2"'#.&66#9+#7+,1#'3)66#&@#2"+#)''/3+'# α#=#K#)"0 .- = .*?#=%+,+@2,+-#+T(+*$#&"#()6(/6)$&2"'#$%)$#0+*+"0#(,&$&()661#2"#$%+#7)6/+#2@#α#:+?L?-#$%+#()6(/6)5 $&2"#2@#9)'+#(/,,+"$>-#2"+#/'/)661#)''/3+'#α ! K?
EXERCISES 6.29 D2,#$%+#(&,(/&$#&"#D&L?#W?Ma-#@&"0#$%+#$2$)6#(/,,+"$#0,)."#@,23#$%+#*2.+,#'/**61?#\+"(+#@&"0#$%+ *2.+,#0&''&*)$+0#&"#$%+#(&,(/&$? Ans. 8\^,'@`,XP,'W 6.30 !"$,/(#/3(&,(),L(;<,MX<\O,(0,&2,9$,/2))$/&$-,&2,&"$,/(#/3(&,(),L(;<,X
6.29
Figure E6.30
Ans. +N
6.3 BJT Circuits at DC
395
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On
0 3.9 mA 5 – 0.7 = 10 + 101 × 1 0.039 mA
Off 0
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(b)
Figure 6.30 ET)3*6+#W?KM8#;'<#(&,(/&$H#;&<#)")61'&'#.&$%#$%+#'$+*'#"/39+,+0?
Solution ;1#+T)3&"&"L#$%+#(&,(/&$-#.+#(2"(6/0+#$%)$#$%+#$.2#$,)"'&'$2,'#VK#)"0#VM#()""2$#9+#'&3/6$)"+2/'61#(2"0/($&"L? =%/'#&@#VK#&'#2"-#VM#.&66#9+#2@@-#)"0#7&(+#7+,')?#I''/3+#$%)$#VM#&'#2"?#!$#@2662.'#$%)$#(/,,+"$#.&66#@62.#@,23 L,2/"0#$%,2/L%#$%+#K5UΩ#,+'&'$2,#&"$2#$%+#+3&$$+,#2@#VM?#=%/'#$%+#9)'+#2@#VM#.&66#9+#)$#)#"+L)$&7+#726$)L+-#)"0 9)'+#(/,,+"$#.&66#9+#@62.&"L#2/$#2@#$%+#9)'+#$%,2/L%#$%+#KP5UΩ#,+'&'$2,#)"0#&"$2#$%+#+G5]#'/**61?#=%&'#&'#&3*2'5 '&96+-#'&"(+#&@#$%+#9)'+#&'#"+L)$&7+-#(/,,+"$#&"#$%+#KP5UΩ#,+'&'$2,#.&66#%)7+#$2#@62.#&"$2#$%+#9)'+?#=%/'#.+#(2"5 (6/0+#$%)$#2/,#2,&L&")6#)''/3*$&2"g$%)$#VM#&'#2"g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
##########
EXERCISES 6.31 K2+.$,&"$,7#29+$',(),MA*'7+$,X
396 Chapter 6 Bipolar Junction Transistors (BJTs)
6.4 Applying the BJT in Amplifier Design W$,)24,9$;(),23#,0&3-:,21,&"$,3&(+(>*&(2),21,&"$,BC!,(),&"$,-$0(;),21,*'7+(1($#0\,,!"$,9*0(0 12#,&"(0,('72#&*)&,*77+(/*&(2),(0,&"*&,4"$),27$#*&$-,(),&"$,*/&(.$,'2-$5,&"$,BC!,13)/&(2)0,*0,* .2+&*;$%/2)++$-,/3##$)&,023#/$Y,&"$,9*0$]$'(&&$#,.2+&*;$, v )* ,/2)+0,&"$,/2++$/&2#,/3##$)& $ - <, @+&"23;", &"$, /2)+, #$+*&(2)0"(7, (0, )2)+()$*#, T$A72)$)&(*+V5, 4$, 4(++, 0"2#&+:, -$.(0$, * '$&"2-,12#,29&*()();,*+'20&%+()$*#,*'7+(1(/*&(2),1#2',&"(0,13)-*'$)&*++:,)2)+()$*#,-$.(/$<
6.4.1 Obtaining a Voltage Amplifier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v )* ,(0,&"$,()73&,.2+&*;$5, > - ,TG)24),*0,*,+*'2-%!(#($'0)!V,/2).$#&0,&"$,/2++$/&2#,/3##$)&, $ - ,&2 *,.2+&*;$,T $ - > - V5,*)-, + -- ,(0,&"$,0377+:,.2+&*;$,&"*&,724$#0,37,&"$,*'7+(1($#,*)-5,&2;$&"$# 4(&", > - 5,$0&*9+(0"$0,27$#*&(2),(),&"$,*/&(.$,'2-$5,*0,4(++,9$,0"24),0"2#&+:< VCC
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Cut off iC
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401
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6.5 Small-Signal Operation and Models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v#4,&"*&,(0,037$#('% 720$-,2),+)*< Y+# (2"'&0+,# @&,'$# $%+# 0(# 9&)'# (2"0&$&2"'# 91# '+$$&"L# $%+# '&L")6# v#4# $2# h+,2?# =%+# (&,(/&$ ,+0/(+'#$2#$%)$#&"#D&L?#W?NW:9>-#)"0#.+#()"#.,&$+#$%+#@2662.&"L#,+6)$&2"'%&*'#@2,#$%+#0(#(/,5 ,+"$'#)"0#726$)L+'8
.- = .6 4
+ )* ⁄ + ,
.* = .- ⁄ α
TX<\XV TX<\NV
403
404 Chapter 6 Bipolar Junction Transistors (BJTs) iC
IC RC
RC iB
$
vbe
$ $ % vBE
VBE
%
vCE
IB
VCC
$ VCE
%
VCC
%
VBE
iE
IE
(b)
(a)
Figure 6.36 ;'<#F2"(+*$/)6#(&,(/&$#$2#&66/'$,)$+#$%+#2*+,)$&2"#2@#$%+#$,)"'&'$2,#)'#)"#)3*6&@&+,?#;&<#=%+#(&,5 (/&$#2@#;'<#.&$%#$%+#'&L")6#'2/,(+#v#4#+6&3&")$+0#@2,#0(#:9&)'>#)")61'&'?
.) = .- ⁄ β
TX<\EV
+ -* = + -- ] . - > -
TX<\DV
B97&2/'61-#@2,#)($&7+5320+#2*+,)$&2"-#+-#'%2/60#9+#L,+)$+,#$%)"#:+)#−#P?e>#91#)"#)32/"$ $%)$#)662.'#@2,#$%+#,+V/&,+0#'&L")6#'.&"L#)$#$%+#(266+($2,?
6.5.1 The Collector Current and the Transconductance =1,*,0(;)*+, v#4,(0,*77+($-,*0,0"24),(),L(;<,X<\XT*V5,&"$,&2&*+,()0&*)&*)$230,9*0$]$'(&&$#,.2+&% *;$,v)*,9$/2'$0 v )*
= + )* + v #4
62##$072)-();+:5,&"$,/2++$/&2#,/3##$)&,9$/2'$0
$- = .6 4 = .6 4
v )* ⁄ + ,
= .6 4
( + )* + v #4 ) ⁄ + ,
+ )* ⁄ + , v #4 ⁄ + ,
4
c0$,21,MS<,TX<\XV,:($+-0
$- = .- 4
v#4 ⁄ + ,
TX<8OV
Q245,(1,v#4 *,+, 5,4$,'*:,*77#2A('*&$,MS<,TX<8OV,*0 v
#4 5 $ - #! . - K + 55555 +,
TX<8?V
R$#$,4$,"*.$,$A7*)-$-,&"$,$A72)$)&(*+,(),MS<,TX<8OV,(),*,0$#($0,*)-,#$&*()$-,2)+:,&"$,1(#0& &42,&$#'0<,!"(0,*77#2A('*&(2)5,4"(/",(0,.*+(-,2)+:,12#,v#4,+$00,&"*),*77#2A('*&$+:,?O,'_5,(0 #$1$##$-,&2,*0,&"$,("'++5(#60'+-'44%*?#"'$#*0<,c)-$#,&"(0,*77#2A('*&(2)5,&"$,&2&*+,/2++$/&2# /3##$)&,(0,;(.$),9:,MS<,TX<8?V,*)-,/*),9$,#$4#(&&$)
.v $ - = . - + 55555 + , #4
TX<8PV
6.5 Small-Signal Operation and Models
!"30,&"$,/2++$/&2#,/3##$)&,(0,/2'720$-,21,&"$,-/,9(*0,.*+3$,.-,*)-,*,0(;)*+,/2'72)$)&,$E 5
.$ E = 55555 v + , #4
TX<8\V
!"(0, $S3*&(2), #$+*&$0,&"$,0(;)*+, /3##$)&, (), &"$,/2++$/&2#,&2, &"$, /2##$072)-();,9*0$]$'(&&$# 0(;)*+,.2+&*;$<,=&,/*),9$,#$4#(&&$),*0
$ E = C I v #4
TX<88V
4"$#$,CI,(0,/*++$-,&"$,$%'0()*02/)$'0)!5,*)-,1#2',MS<,TX<8\V5,(&,(0,;(.$),9:
.C I = 55555 +,
TX<8^V
W$,290$#.$,&"*&,&"$,*)0/2)-3/&*)/$,21,&"$,BC!,(0,-(#$/&+:,7#272#&(2)*+,&2,&"$,/2++$/&2#,9(*0 /3##$)&,.-<,!"30,&2,29&*(),*,/2)0&*)&,7#$-(/&*9+$,.*+3$,12#,CI5,4$,)$$-,*,/2)0&*)&,7#$-(/&*9+$ .-<,L()*++:5,4$,)2&$,&"*&,BC!0,"*.$,#$+*&(.$+:,"(;",*)0/2)-3/&*)/$,T*0,/2'7*#$-,&2,IJK% LM!05,4"(/",4$,0&3-($-,(),6"*7&$#,^V`,12#,()0&*)/$5,*&,.-,=,?,'@5, C I ! eP#3IZ]? @,;#*7"(/*+,()&$#7#$&*&(2),12#,CI,(0,;(.$),(),L(;<,X<\N5,4"$#$,(&,(0,0"24),&"*&,CI,(0,$S3*+ &2,&"$,0+27$,21,&"$,$- ]v)*,/"*#*/&$#(0&(/,/3#.$,*&,$-,=,.-,T(<$<5,*&,&"$,9(*0,72()&,kV<,!"305
∂ $C I = 55555555555
∂ v )*
TX<8XV $ - =. -
Q
Figure 6.37 [&"+),#2*+,)$&2"#2@#$%+#$,)"'&'$2,#/"0+,#$%+#'3)665'&L")6#(2"0&$&2"8#I#'3)66#'&L")6#v#4#.&$%#) $,&)"L/6),#.)7+@2,3#&'#'/*+,&3*2'+0#2"#$%+#0(#726$)L+#+)*?#!$#L&7+'#,&'+#$2#)#(266+($2,#'&L")6#(/,,+"$#$E-#)6'2 2@ $,&)"L/6),#.)7+@2,3-#'/*+,&3*2'+0#2"#$%+#0(#(/,,+"$#.-?#\+,+-#$E#=#CIv#4-#.%+,+#CI#&'#$%+#'62*+#2@#$%+#$- Qv)* (/,7+#)$#$%+#9&)'#*2&"$#l?
405
406 Chapter 6 Bipolar Junction Transistors (BJTs) !"$,0'*++%0(;)*+,*77#2A('*&(2),('7+($0,G$$7();,&"$,0(;)*+,*'7+(&3-$,0311(/($)&+:,0'*++,&"*& %"4('?$%!8$B8(4B?($E?458?%8'!8'&I%B?M&$!4'(8B4CI4!?8%G8?D48$- Rv)*843"%!4!?$'&8EU(F4@,=)/#$*0% ();,&"$,0(;)*+,*'7+(&3-$,4(++,#$03+&,(),&"$,/2++$/&2#,/3##$)&,"*.();,/2'72)$)&0,)2)+()$*#+: #$+*&$-,&2,v#4<,!"(05,21,/23#0$5,(0,&"$,0*'$,*77#2A('*&(2),&"*&,4$,-(0/300$-,(),&"$,/2)&$A&,21 &"$,*'7+(1($#,*)01$#,/3#.$,(),K$/&(2),X<8< !"$,*)*+:0(0,*92.$,03;;$0&0,&"*&,12#,0'*++,0(;)*+0,Tv#4,*,+,V5,&"$,*)0(0&2#,9$"*.$0,*0,* .2+&*;$%/2)++$-,/3##$)&,023#/$<,!"$,()73&,72#&,21,&"(0,/2)++$-,023#/$,(0,9$&4$$),9*0$ *)-,$'(&&$#5,*)-,&"$,23&73&,72#&,(0,9$&4$$),/2++$/&2#,*)-,$'(&&$#<,!"$,*)0/2)-3/&*)/$,21 &"$,/2)++$-,023#/$,(0,CI5,*)-,&"$,23&73&,#$0(0&*)/$,(0,()1()(&$<,!"$,+*&&$#,(-$*+,7#27$#&:,(0,* #$03+&,21,23#,1(#0&%2#-$#,'2-$+,21,*)0(0&2#,27$#*&(2),(),4"(/",&"$,/2++$/&2#,.2+&*;$,"*0,)2 $11$/&,2),&"$,/2++$/&2#,/3##$)&,(),&"$,*/&(.$,'2-$<,@0,4$,"*.$,0$$),(),K$/&(2),X
EXERCISES 6.34 ^'+#EV?#:W?eW>#$2#0+,&7+#$%+#+T*,+''&2"#@2,#CI#&"#EV?#:W?eG>? 6.35 6*+/3+*&$,&"$,.*+3$,21,CI,12#,*,BC!,9(*0$-,*&,.-,d,O<^,'@< Ans. MP#3IZ]
6.5.2 The Base Current and the Input Resistance at the Base !2, -$&$#'()$, &"$, #$0(0&*)/$, 0$$), 9:, v#45, 4$, 1(#0&, $.*+3*&$, &"$, &2&*+, 9*0$, /3##$)&, $), 30(); MS< TX<8PV5,*0,12++240Y
$ . K .$ ) = 555-5 = 555-5 + 555 55555 v β β β + , #4 !"305
$) = .) + $#
TX<8NV
4"$#$,.),(0,$S3*+,&2, . - ⁄ β *)-,&"$,0(;)*+,/2'72)$)&,$#,(0,;(.$),9:
K .$ # = 555 55555 v β + , #4
TX<8EV
C $ # = 55555I v #4
TX<8DV
K390&(&3&();,12#, . - ⁄ + , ,9:,CI,;(.$0
β
!"$,0'*++%0(;)*+,()73&,#$0(0&*)/$,9$&4$$),9*0$,*)-,$'(&&$#5,&%%P$!C8$!?%8?D48#'B4W,(0,-$)2&$9:,(π,*)-,(0,-$1()$-,*0 v
#4 5 ( π ≡ 55555 $#
TX<^OV
6.5 Small-Signal Operation and Models
c0();,MS<,TX<8DV,;(.$0
β
( π = 55555 CI
TX<^?V
!"30,(π,(0,-(#$/&+:,-$7$)-$)&,2),β,*)-,(0,().$#0$+:,7#272#&(2)*+,&2,&"$,9(*0,/3##$)&,.- <,K390&(% &3&();, 12#, CI, (), MS<, TX<^?V, 1#2', MS<, TX<8^V, *)-, #$7+*/();, .- oβ, 9:, .), ;(.$0, *), *+&$#)*&(.$ $A7#$00(2),12#,(π 5
+ ( π = 55555, .)
TX<^PV
EXERCISE 6.36 I#;<=#)3*6&@&+,#&'#9&)'+0#$2#2*+,)$+#)$#)#(2"'$)"$#(266+($2,#(/,,+"$# . - d P?G #3I#&,,+'*+($&7+#2@ $%+#7)6/+# β ?#!@#$%+#$,)"'&'$2,#3)"/@)($/,+,#'*+(&@&+'# β #$2#,)"L+#@,23#GP#$2#MPP-#L&7+#$%+#+T*+($+0 ,)"L+#2@# C I-# . ) - #)"0# ( π ? Ans. C I ,(0,/2)0&*)&,*&,PO,'@o_`, . ) d KP ,µ@,&2,P<^,µ@`, ( π d M?G,G Ω ,&2,?O,G Ω
6.5.3 The Emitter Current and the Input Resistance at the Emitter !"$,&2&*+,$'(&&$#,/3##$)&,$*,/*),9$,-$&$#'()$-,1#2'
$ . $ $ * = 555-5 = 555-5 + 555E
α
α
α
!"305,
$* = .* + $4
TX<^\V
4"$#$,.*,(0,$S3*+,&2,.- oα,*)-,&"$,0(;)*+,/3##$)&,$4,(0,;(.$),9:
$ . .5 v #4 = 55555* v #4 $ 4 = 555E = 555555555 α α +, +,
TX<^8V
=1,4$,-$)2&$,&"$,0'*++%0(;)*+,#$0(0&*)/$,9$&4$$),9*0$,*)-,$'(&&$#,&%%P$!C8$!?%8?D484I$??4(,9: (45,(&,/*),9$,-$1()$-,*0, v
#4 5 ( 4 ≡ 55555 $4
TX<^^V
c0();,MS<,TX<^8V,4$,1()-,&"*&,(45,/*++$-,&"$,!"#$$!%-%!(#($'0)!5,(0,;(.$),9:
+ ( 4 = 55555, .*
TX<^XV
α K ( 4 = 55555 !# 55555 CI CI
TX<^NV
62'7*#(02),4(&",MS<,TX<8^V,#$.$*+0,&"*&
407
408 Chapter 6 Bipolar Junction Transistors (BJTs) !"$,#$+*&(2)0"(7,9$&4$$),(π,*)-,(4,/*),9$,123)-,9:,/2'9()();,&"$(#,#$07$/&(.$,-$1()(&(2)0,() MS0<,TX<^OV,*)-,TX<^^V,*0, v #4
= $# (π = $4 (4
!"305
( π = ( $ 4 ⁄ $ # )( 4 4"(/",:($+-0
( π = ( β + K )( 4
TX<^EV
L(;3#$,X<\E,(++30*&$0,&"$,-$1()(&(2),21,(π,*)-,(4<
ib $
$ vbe
vbe
r+ #
% vbe ib
% re #
ie
vbe ie
Figure 6.38 !66/'$,)$&"L#$%+#0+@&"&$&2"#2@#(π#)"0#(4?
EXERCISE 6.37 I#;<=#%)7&"L#β# =#KPP#&'#9&)'+0#)$#)#0(#(266+($2,#(/,,+"$#2@#K#3I?#D&"0#$%+#7)6/+#2@#CI-#(4-#)"0#(π#)$ $%+#9&)'#*2&"$? Ans. eP#3IZ]H#25 ΩH#M?G#UΩ
6.5.4 Voltage Gain W$,"*.$,$0&*9+(0"$-,*92.$,&"*&,&"$,*)0(0&2#,0$)0$0,&"$,9*0$]$'(&&$#,0(;)*+, v#4,*)-,/*30$0,* 7#272#&(2)*+,/3##$)&,CIv#4,&2,1+24,(),&"$,/2++$/&2#,+$*-,*&,*,"(;",T(-$*++:,()1()(&$V,('7$-*)/$ +$.$+<,=),&"(0,4*:,&"$,*)0(0&2#,(0,*/&();,*0,*,.2+&*;$%/2)++$-,/3##$)&,023#/$<,!2,29&*(),*) 23&73&,.2+&*;$,0(;)*+5,4$,'*:,12#/$,&"(0,/3##$)&,&2,1+24,&"#23;",*,#$0(0&2#5,*0,(0,-2)$,(),L(;< X<\XT*V<,!"$),&"$,&2&*+,/2++$/&2#,.2+&*;$,v-*,4(++,9$ v -*
= + -- ] $ - > = + -- ] ( . - + $ E )> = ( + -- ] . - > - ) ] $ E > = + -* ] $ E > -
TX<^DV
6.5 Small-Signal Operation and Models
R$#$,&"$,S3*)&(&:,+-*,(0,&"$,-/,9(*0,.2+&*;$,*&,&"$,/2++$/&2#5,*)-,&"$,0(;)*+,.2+&*;$,(0,;(.$),9: v E4
= ] $ E > - = ] C I v #4 > -
TX
= ( ] C I > - ) v #4 !"30,&"$,.2+&*;$,;*(),21,&"(0,*'7+(1($#,/v,(0 v
E4 5 = ]CI >/ v ≡ 55555
v #4
TX
R$#$, *;*(), 4$, )2&$, &"*&, 9$/*30$, CI, (0, -(#$/&+:, 7#272#&(2)*+, &2, &"$, /2++$/&2#, 9(*0, /3##$)&5 &"$ ;*(),4(++,9$,*0,0&*9+$,*0,&"$,/2++$/&2#,9(*0,/3##$)&,(0,'*-$<,K390&(&3&();,12#,CI,1#2' MS<,TX<8^V,$)*9+$0,30,&2,$A7#$00,&"$,;*(),(),&"$,12#'
.- >5 / v = ] 5555555555 +,
TX
4"(/",(0,(-$)&(/*+,&2,&"$,$A7#$00(2),4$,-$#(.$-,(),K$/&(2),X<8,TMS<,X<\?V<,,,,,
EXERCISE 6.38 !"#$%+#(&,(/&$#2@#D&L?#W?NW:)>-#+)*#&'#)04/'$+0#$2#1&+60#)#0(#(266+($2,#(/,,+"$#2@#K#3I?#[+$#+--#=#KG#]>- =#KP#UΩ-#)"0#β# =#KPP?#D&"0#$%+#726$)L+#L)&"# v E4 ⁄ v #4 ? !@#v#4#=#P?PPG#'&" ω ?#726$-#@&"0#v-:?>#)"0#$):?>? Ans. ] ePP#]Z]H #G#Q#M#'&" ω ?#726$'H#KP#+#M#'&" ω ?#µI
6.5.5 Separating the Signal and the DC Quantities !"$, *)*+:0(0, *92.$, ()-(/*&$0, &"*&, $.$#:, /3##$)&, *)-, .2+&*;$, (), &"$, *'7+(1($#, /(#/3(&, 21 L(;< X<\XT*V,(0,/2'720$-,21,&42,/2'72)$)&0Y,*,-/,/2'72)$)&,*)-,*,0(;)*+,/2'72)$)&<,L2# ()0&*)/$5, v)*,=,+)*,+,v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
RC C ib " vbe /r+ B vbe
$ %
$ vce
$ vbe %
ic " gm vbe
%
E
vbe ie " r e
Figure 6.39 =%+# )3*6&@&+,# (&,(/&$# 2@# D&L?# W?NW:)># .&$%# $%+ 0(# '2/,(+'# :+)*# )"0# +--># +6&3&")$+0# :'%2,$5(&,(/&$+0>?# =%/' 2"61#$%+#'&L")6#(23*2"+"$'#),+#*,+'+"$?#b2$+#$%)$#$%&'#&'#)#,+*5 ,+'+"$)$&2"#2@#$%+#'&L")6#2*+,)$&2"#2@#$%+#;<=#)"0#"2$#)"#)($/)6 )3*6&@&+,#(&,(/&$?
409
410 Chapter 6 Bipolar Junction Transistors (BJTs) /3##$)&,023#/$05,&"$0$,423+-,"*.$,9$$),#$7+*/$-,9:,27$),/(#/3(&0<,Q2&$5,"24$.$#5,&"*&,&"$ /(#/3(&,21,L(;<,X<\D,(0,30$13+,2)+:,(),02,1*#,*0,(&,0"240,&"$,.*#(230,0(;)*+,/3##$)&0,*)-,.2+&% *;$0`,(&,(0,!%?,*),*/&3*+,*'7+(1($#,/(#/3(&5,0()/$,&"$,-/,9(*0,/(#/3(&,(0,)2&,0"24)< L(;3#$,X<\D,*+02,0"240,&"$,$A7#$00(2)0,12#,&"$,/3##$)&,()/#$'$)&0,T$E5,$#5,*)-,$4V,29&*()$4"$),*,0'*++,0(;)*+,v#4,(0,*77+($-<,!"$0$,#$+*&(2)0"(70,/*),9$,#$7#$0$)&$-,9:,*,/(#/3(&<,K3/",*,/(#% /3(&,0"23+-,"*.$,&"#$$,&$#'()*+0[65,B5,*)-,M[*)-,0"23+-,:($+-,&"$,0*'$,&$#'()*+,/3##$)&0,()-(% /*&$-,(),L(;<,X<\D<,!"$,#$03+&();,/(#/3(&,(0,&"$),40U$F'&4!?8?%8?D48?('!B$B?%(8'B8G'(8'B8BI'&&MB$C!'& %"4('?$%!8$B8E%!E4(!45W,*)-,&"30,(&,/*),9$,/2)0(-$#$-,*),$S3(.*+$)&,0'*++%0(;)*+,/(#/3(&,'2-$+<
6.5.6 The Hybrid-π Model @),$S3(.*+$)&,/(#/3(&,'2-$+,12#,&"$,BC!,(0,0"24),(),L(;<,X<8OT*V<,!"(0,'2-$+,#$7#$0$)&0,&"$,BC! *0,*,.2+&*;$%/2)++$-,/3##$)&,023#/$,*)-,$A7+(/(&+:,()/+3-$0,&"$,()73&,#$0(0&*)/$,+22G();,()&2 &"$,9*0$5,(π <,!"$,'2-$+,29.(230+:,:($+-0,$E,=,CIv#4,*)-, $ # = v#4 ⁄ ( π ? ,Q2&,02,29.(2305,"24$.$#5,(0 &"$,1*/&,&"*&,&"$,'2-$+,*+02,:($+-0,&"$,/2##$/&,$A7#$00(2),12#,$4<,!"(0,/*),9$,0"24),*0,12++240Y @&,&"$,$'(&&$#,)2-$,4$,"*.$ v
v
#4 #4 5 + C I v #4 = 55555 5 ( K + CI (π ) $ 4 = 55555 (π (π
v #4 (π 5 ( K + β ) = v #4 ## 55555555555 5 = 55555 (π K+β = v #4 ⁄ ( 4
@,0+(;"&+:,-(11$#$)&,$S3(.*+$)&%/(#/3(&,'2-$+,/*),9$,29&*()$-,9:,$A7#$00();,&"$,/3##$)& 21,&"$,/2)++$-,023#/$,TCIv#4V,(),&$#'0,21,&"$,9*0$,/3##$)&,$#,*0,12++240Y
C I v #4 = C I ( $ # ( π ) = ( C I ( π )$ # = β $ # !"(0,#$03+&0,(),&"$,*+&$#)*&(.$,$S3(.*+$)&%/(#/3(&,'2-$+,0"24),(),L(;<,X<8OT9V<,R$#$,&"$,*)% 0(0&2#,(0,#$7#$0$)&$-,*0,*,/3##$)&%/2)++$-,/3##$)&,023#/$5,4(&",&"$,/2)+,/3##$)&,9$();,$#<
ic
ib B
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ie (a)
E
Figure 6.40 =.2#'6&L%$61#0&@@+,+"$#7+,'&2"'#2@#$%+#%19,&05π#320+6#@2,#$%+#'3)665'&L")6#2*+,)$&2"#2@#$%+ ;<=?#=%+#+V/&7)6+"$#(&,(/&$#&"#;'<#,+*,+'+"$'#$%+#;<=#)'#)#726$)L+5(2"$,266+0#(/,,+"$#'2/,(+#:)#$,)"'(2"5 0/($)"(+#)3*6&@&+,>-#)"0#$%)$#&"#;&<#,+*,+'+"$'#$%+#;<=#)'#)#(/,,+"$5(2"$,266+0#(/,,+"$#'2/,(+#:)#(/,,+"$ )3*6&@&+,>?
6.5 Small-Signal Operation and Models
!"$,&42,'2-$+0,21,L(;<,X<8O,*#$,0('7+(1($-,.$#0(2)0,21,4"*&,(0,G)24),*0,&"$,":9#(-%π '2-$+<,!"(0,(0,&"$,'20&,4(-$+:,30$-,'2-$+,12#,&"$,BC!< =&, (0, ('72#&*)&, &2, )2&$, &"*&, &"$, 0'*++%0(;)*+, $S3(.*+$)&, /(#/3(&0, 21, L(;<, X<8O, '2-$+, &"$ 27$#*&(2), 21, &"$, BC!, '?8 '8 C$F4!8 #$'B8 "%$!?<, !"(0, 0"23+-, 9$, 29.(230, 1#2', &"$, 1*/&, &"*& &"$ '2-$+,7*#*'$&$#0,CI,*)-,(π,-$7$)-,2),&"$,.*+3$,21,&"$,-/,9(*0,/3##$)&,.- 5,*0,()-(/*&$-,() L(;<,X<8O<,=&,(0,()&$#$0&();,*)-,30$13+,&2,)2&$,&"*&,&"$,'2-$+0,21,L(;<,X<8O,T*V,*)-,T9V,*#$,&"$ 0'*++%0(;)*+,.$#0(2)0,21,&"$,'2-$+0,21,L(;<,X<^T/V,*)-,T-V5,#$07$/&(.$+:<,K7$/(1(/*++:5,290$#.$ &"*&,(π ,(0,&"$,()/#$'$)&*+,#$0(0&*)/$,21,1)<
EXERCISE 6.39 L2#,&"$,'2-$+,(),L(;<,X<8OT9V,0"24,&"*&,$E,=,CIv#488*)-, $ 4 = v #4 ⁄ ( 4 ?
6.5.7 The T Model @+&"23;", &"$,":9#(-%π, '2-$+, T(),2)$,21,(&0, &42,.*#(*)&0,0"24),(),L(;<,X<8OV, /*),9$,30$&2 /*##:,23&,0'*++%0(;)*+,*)*+:0(0,21,*):,*)0(0&2#,/(#/3(&5,&"$#$,*#$,0(&3*&(2)0,(),4"(/",*) *+&$#)*&(.$, '2-$+5, 0"24), (), L(;<, X<8?5, (0, '3/", '2#$, /2).$)($)&<, !"(0, '2-$+5, /*++$-, &"$ @ "*2!+5,(0,0"24),(),&42,.$#0(2)0,(),L(;<,X<8?<, !"$,'2-$+,21,L(;<,X<8?T*V,#$7#$0$)&0,&"$ BC!,*0,*,.2+&*;$%/2)++$-,/3##$)&,023#/$,4(&",&"$,/2)+,.2+&*;$,9$();,v#4<,R$#$5,"24$.$#5 &"$,#$0(0&*)/$,9$&4$$),9*0$,*)-,$'(&&$#5,+22G();,()&2,&"$,$'(&&$#5,(0,$A7+(/(&+:,0"24)<,L#2' L(;<,X<8?T*V,4$,0$$,/+$*#+:,&"*&,&"$,'2-$+,:($+-0,&"$,/2##$/&,$A7#$00(2)0,12#,$E,*)-,$4<,L2#,$# 4$,)2&$,&"*&,*&,&"$,9*0$,)2-$,4$,"*.$,,
C ic
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Figure 6.41 =.2#'6&L%$61#0&@@+,+"$#7+,'&2"'#2@#.%)$#&'#U"2."#)'#$%+#,8I%54@#$%+#;<=?#=%+#(&,(/&$#&" ;'< &'#)#726$)L+5(2"$,266+0#(/,,+"$#'2/,(+#,+*,+'+"$)$&2"#)"0#$%)$#&"#;&<#&'#)#(/,,+"$5(2"$,266+0#(/,,+"$#'2/,(+ ,+*,+'+"$)$&2"?# =%+'+# 320+6'# +T*6&(&$61# '%2.# $%+# +3&$$+,# ,+'&'$)"(+# (4# ,)$%+,# $%)"# $%+# 9)'+# ,+'&'$)"(+# (π @+)$/,+0#&"#$%+#%19,&05π#320+6?
411
412 Chapter 6 Bipolar Junction Transistors (BJTs) v
v
#4 #4 5 ( K ] CI (4 ) $ # = 55555 5 ] C I v #4 = 55555 (4 (4
β 5 #4 #4 5 ( K ] α ) = 55555 5 K ] 55555555555 = 55555 (4 (4 β+K v
v
v
v
#4 #4 5 = 55555 5 = 555555555555555555555 ( β + K )( 4 (π
)'#'%2/60#9+#$%+#()'+? =1,(),&"$,'2-$+,21,L(;<,X<8?T*V,&"$,/3##$)&,21,&"$,/2)++$-,023#/$,(0,$A7#$00$-,(),&$#'0 21,&"$,$'(&&$#,/3##$)&,*0
C I v #4 = C I ( $ 4 ( 4 ) = ( C I ( 4 )$ 4 = α $ 4 4$,29&*(),&"$,*+&$#)*&(.$,!,'2-$+,0"24),(),L(;<,X<8?T9V<,R$#$,&"$,BC!,(0,#$7#$0$)&$-,*0,* /3##$)&%/2)++$-,/3##$)&,023#/$,93&,4(&",&"$,/2)+,0(;)*+,9$();,$4< !$#&'#&"$+,+'$&"L#)"0#/'+@/6#$2#"2$+#$%)$#$%+#320+6'#2@#D&L?#W?eK:)>#)"0#:9>#),+#$%+#'3)665 '&L")6#7+,'&2"'#2@#$%+#320+6'#&"#D&L?#W?G:)>#)"0#:9>-#,+'*+($&7+61?#C*+(&@&()661#29'+,7+#$%)$#(4 &'#$%+#&"(,+3+"$)6#,+'&'$)"(+#2@#1*?
6.5.8 Small-Signal Models of the pnp Transistor @+&"23;",&"$,0'*++%0(;)*+,'2-$+0,(),L(;0<,X<8O,*)-,X<8?,4$#$,-$.$+27$-,12#,&"$,/*0$,21,&"$ !"!,*)0(0&2#5,&"$:,*77+:,$S3*++:,4$++,&2,&"$,"!",*)0(0&2#,A$?D8!%8ED'!C48$!8"%&'($?$4B<
6.5.9 Application of the Small-Signal Equivalent Circuits =%+# )7)&6)9&6&$1# 2@# $%+# '3)665'&L")6# ;<=# (&,(/&$# 320+6'# 3)U+'# $%+# )")61'&'# 2@# $,)"'&'$2, )3*6&@&+,#(&,(/&$'#)#'1'$+3)$&(#*,2(+''?#=%+#*,2(+''#(2"'&'$'#2@#$%+#@2662.&"L#'$+*'8 1. M+('()*&$,&"$,0(;)*+,023#/$,*)-,-$&$#'()$,&"$,-/,27$#*&();,72()&,21,&"$,BC!,*)-,(),7*#% &(/3+*#,&"$,-/,/2++$/&2#,/3##$)&,.-< 2. 6*+/3+*&$, &"$, .*+3$0, 21, &"$, 0'*++%0(;)*+, '2-$+, 7*#*'$&$#0Y, C I = . - ⁄ + , - , ( π = β ⁄ C I *)-, ( 4 = + , ⁄ . * = α ⁄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
6.5 Small-Signal Operation and Models
Example 6.14 Y+#.&'%#$2#)")61h+#$%+#$,)"'&'$2,#)3*6&@&+,#'%2."#&"#D&L?#W?eM:)>#$2#0+$+,3&"+#&$'#726$)L+#L)&"# v % ⁄ v $ ? I''/3+#β# =#KPP? VCC
10 V
$10 V 2.3 mA
VC
100 k
RBB
3 k&
3k
RC
vo
0.023 mA
vi VBB
$3.1 V
$3 V 100 k&
$0.7 V 2.323 mA
3V
(a )
(b)
Re
RBB
vi
RBB " 100 k& B
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E (d)
% (c) Figure 6.42 ET)3*6+#W?Ke8#;'<#)3*6&@&+,#(&,(/&$H#;&<#(&,(/&$#@2,#0(#)")61'&'H#;)<#)3*6&@&+,#(&,(/&$#.&$%#0(#'2/,(+' ,+*6)(+0#91#'%2,$#(&,(/&$'H#;2<-)3*6&@&+,#(&,(/&$#.&$%#$,)"'&'$2,#,+*6)(+0#91#&$'#%19,&05π, '3)665'&L")6#320+6'?
Solution Y+#'%)66#@2662.#$%+#@&7+5'$+*#*,2(+''#2/$6&"+0#)927+8
1. !"$,1(#0&,0&$7,(),&"$,*)*+:0(0,/2)0(0&0,21,-$&$#'()();,&"$,S3($0/$)&,27$#*&();,72()&<,L2#,&"(0,73#% 720$,4$,*003'$,&"*&,v$,=,O,*)-,&"30,29&*(),&"$,-/,/(#/3(&,0"24),(),L(;<,X<8PT9V<,!"$,-/,9*0$,/3#% #$)&,4(++,9$
413
414 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.14 continued
+ )) ] + )* 5 . ) = 55555555555555555555555 > )) N ] P?d ! 5555555555555555 = P?PMN#3I KPP =%+#0(#(266+($2,#(/,,+"$#.&66#9+ . - = β . ) #=#KPP × P?PMN = M?N#3I =%+#0(#726$)L+#)$#$%+#(266+($2,#.&66#9+ + - = + -- ] . - > = +?O,−,P<\,× 3 = +3.1 _ C&"(+#+)#)$#+P?d#]#&'#6+''#$%)"#+- -#&$#@2662.'#$%)$#&"#$%+#V/&+'(+"$#(2"0&$&2"#$%+#$,)"'&'$2,#.&66#9+ 2*+,)$&"L#&"#$%+#)($&7+#320+?#=%+#0(#)")61'&'#&'#&66/'$,)$+0#&"#D&L?#W?eM:9>?
2. R*.();,-$&$#'()$-,&"$,27$#*&();,72()&5,4$,/*),)24,7#2/$$-,&2,-$&$#'()$,&"$,0'*++%0(;)*+,'2-$+ 7*#*'$&$#0Y + MG#3] ( 4 = 55555,5 = 55555555555555555555555555555555555555 = KP?f#Ω .* ( M?N ⁄ P?aa )#3I .M?N#3I 5 = 555555555555555555 = aM#3IZ] C I = 55555 MG#3] +,
β KPP ( π = 555555 = 555555555 = K?Pa#UΩ CI aM 3. U$7+*/();,+)),*)-,+--8,4(&",0"2#&,/(#/3(&0,#$03+&0,(),&"$,/(#/3(&,(),L(;<,X<8PT/V< 4. !2,/*##:,23&,&"$,0'*++%0(;)*+,*)*+:0(05,(&,(0,$S3*++:,/2).$)($)&,&2,$'7+2:,$(&"$#,21,&"$,&42,":9#(-% π5,$S3(.*+$)&%/(#/3(&,'2-$+0,21,L(;<,X<8O,&2,#$7+*/$,&"$,*)0(0&2#,(),&"$,/(#/3(&,21,L(;<,X<8PT/V< c0();,&"$,1(#0&,#$03+&0,(),&"$,*'7+(1($#,$S3(.*+$)&,/(#/3(&,;(.$),(),L(;<,X<8PT-V<, 5. I")61'&'#2@#$%+#+V/&7)6+"$#(&,(/&$#&"#D&L?#W?eM:0>#*,2(++0'#)'#@2662.'8 (π v #4 = v $ 55555555555555555555 ( π + > )) K?Pa = v $ 5555555555555555 = P?PKK v $ KPK?Pa
TX
!"$,23&73&,.2+&*;$,v%,(0,;(.$),9: v % = ] C I v #4 > -
= ] aM × P?PKK v $ × N = ] N?Pe v $ =%/'#$%+#726$)L+#L)&"#.&66#9+ v
/ v = 5555% = ] N?Pe #]Z] v$
TX
6.5 Small-Signal Operation and Models
Example 6.15 =2#L)&"#32,+#&"'&L%$#&"$2#$%+#2*+,)$&2"#2@#$,)"'&'$2,#)3*6&@&+,'-#.+#.&'%#$2#(2"'&0+,#$%+#.)7+@2,3'#)$#7),5 &2/'#*2&"$'#&"#$%+#(&,(/&$#)")61h+0#&"#$%+#*,+7&2/'#+T)3*6+?#D2,#$%&'#*/,*2'+#)''/3+#$%)$#v$#%)'#)#$,&)"L/6), .)7+@2,3?#D&,'$#0+$+,3&"+#$%+#3)T&3/3#)3*6&$/0+#$%)$#v$#&'#)662.+0#$2#%)7+?#=%+"-#.&$%#$%+#)3*6&$/0+#2@ v$#'+$#$2#$%&'#7)6/+-#L&7+#$%+#.)7+@2,3'#2@#$%+#$2$)6#V/)"$&$&+'#$):?>-#v)*:?>-#$-:?>-#)"0#v-:?>?
Solution B"+#(2"'$,)&"$#2"#'&L")6#)3*6&$/0+#&'#$%+#'3)665'&L")6#)**,2T&3)$&2"-#.%&(%#'$&*/6)$+'#$%)$#v#4#'%2/60#"2$ +T(++0#)92/$#KP#3]?#!@#.+#$)U+#$%+#$,&)"L/6),#.)7+@2,3# v#4#$2#9+#MP#3]#*+)U5$25*+)U#)"0#.2,U#9)(U5 .),0-#EV?#:W?WN>#()"#9+#/'+0#$2#0+$+,3&"+#$%+#3)T&3/3#*2''&96+#*+)U#2@#v$ v #4 KP vt % = 5555555555555 = 5555555555555 = P?aK#]
P?PKK
P?PKK
=2# (%+(U# .%+$%+,# $%+# $,)"'&'$2,# ,+3)&"'# &"# $%+# )($&7+# 320+# .&$%# v$# %)7&"L# )# *+)U# 7)6/+ vt $ = P?aK#]- .+#%)7+#$2#+7)6/)$+#$%+#(266+($2,#726$)L+?#=%+#726$)L+#)$#$%+#(266+($2,#.&66#(2"'&'$#2@#)#$,&)"5 L/6),#.)7+#v%#'/*+,&3*2'+0#2"#$%+#0(#7)6/+#+-#=#N?K#]?#=%+#*+)U#726$)L+#2@#$%+#$,&)"L/6),#.)7+@2,3#.&66 9+ vt % = vt $ × L)&" = P?aK × N?Pe = M?dd#]
!$#@2662.'#$%)$#.%+"#$%+#2/$*/$#'.&"L'#"+L)$&7+-#$%+#(266+($2,#726$)L+#,+)(%+'#)#3&"&3/3#2@#N?K#Q#M?dd = P?NN ]-#.%&(%#&'#62.+,#$%)"#$%+#9)'+#726$)L+#91#6+''#$%)"#P?e#]?#=%/'#$%+#$,)"'&'$2,#.&66#,+3)&"#&"#$%+ )($&7+#320+#.&$%# v$#%)7&"L#)#*+)U#7)6/+#2@#P?aK#]?#b+7+,$%+6+''-#$2#9+#2"#$%+#')@+#'&0+-#.+#.&66#/'+#) '23+.%)$#62.+,#7)6/+#@2,# vt $ #2@#)**,2T&3)$+61#P?f#]-#)'#'%2."#&"#D&L?#W?eN:)>-#)"0#(23*6+$+#$%+#)")61'&' 2@#$%&'#*,296+3#/$&6&h&"L#$%+#+V/&7)6+"$#(&,(/&$#&"#D&L?#W?eM:0>?#=%+#'&L")6#(/,,+"$#&"#$%+#9)'+#.&66#9+#$,&)"5 L/6),-#.&$%#)#*+)U#7)6/+# $t# #2@ vt
P?f $ 5 = 5555555555555555555555555 = P?PPf#3I $t# = 5555555555555555555 > )) + ( π KPP + K?Pa =%&'# $,&)"L/6),5.)7+# (/,,+"$# .&66# 9+# '/*+,&3*2'+0# 2"# $%+# V/&+'(+"$# 9)'+# (/,,+"$# .)-# )'# '%2."# &"# D&L? W?eN:9>?#=%+#9)'+Q+3&$$+,#726$)L+#.&66#(2"'&'$#2@#)#$,&)"L/6),5.)7+#(23*2"+"$#'/*+,&3*2'+0#2"#$%+#0( +)*#$%)$#&'#)**,2T&3)$+61#P?d#]?#=%+#*+)U#7)6/+#2@#$%+#$,&)"L/6),#.)7+@2,3#.&66#9+ ( ( π + > ))
K?Pa KPP + K?Pa
π vt #4 = vt $ 55555555555555555555 = P?f 5555555555555555555555555 = f?W#3]
=%+#$2$)6#v)*#&'#'U+$(%+0#&"#D&L?#W?eN:(>? =%+#'&L")6#(/,,+"$#&"#$%+#(266+($2,#.&66#9+#$,&)"L/6),#&"#.)7+@2,3-#.&$%#)#*+)U#7)6/+# t$E #L&7+"#91 t$ E = β t$ # = KPP × P?PPf = P?f#3I
=%&'#(/,,+"$#.&66#9+#'/*+,&3*2'+0#2"#$%+#V/&+'(+"$#(266+($2,#(/,,+"$#.-#:=M?N#3I>-#)'#'%2."#&"#D&L? W?eN:0>? =%+#'&L")6#726$)L+#)$#$%+#(266+($2,#()"#9+#29$)&"+0#91#3/6$&*61&"L#v$#91#$%+#726$)L+#L)&"H#$%)$ &'-# vt % = N?Pe × P?f = M?eN#]
D&L/,+# W?eN:+># '%2.'# )# 'U+$(%# 2@# $%+# $2$)6# (266+($2,# 726$)L+# v-# 7+,'/'# $&3+?# b2$+# $%+# *%)'+# ,+7+,')6 9+$.++"#$%+#&"*/$#'&L")6#v$#)"0#$%+#2/$*/$#'&L")6#v%? D&")661-#.+#29'+,7+#$%)$#+)(%#2@#$%+#$2$)6#V/)"$&$&+'#&'#$%+#'/3#2@#)#0(#V/)"$&$1#:@2/"0#@,23#$%+#0(#(&,5 (/&$#&"#D&L?#W?eM9>-#)"0#)#'&L")6#V/)"$&$1#:@2/"0#@,23#$%+#(&,(/&$#&"#D&L?#W?eM0>?
415
416 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.15 continued vi $0.8 V
vˆ i
0
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417
418 Chapter 6 Bipolar Junction Transistors (BJTs)
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419
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423
424 Chapter 6 Bipolar Junction Transistors (BJTs)
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429
430 Chapter 6 Bipolar Junction Transistors (BJTs) J90$#.$,&"*&,"$#$,&"$,'3+&(7+(/*&(.$,1*/&2#,(0, β - ,4"(/",(0,&"$,#*&(2,21, $ E ,&2, $ # H ,&"(0,'*G$0 0$)0$,9$/*30$,4$,*#$,30();,&"$,#*&(2,21,#$0(0&*)/$0,(),&"$,/2++$/&2#,*)-,&"$,9*0$<,!"$,#$*-$# (0,3#;$-,&2,#$1+$/&,2),&"$0$,$A7#$00(2)0,4"(+$,#$1$##();,&2,L(;<,X<^O< Performing the Analysis Directly on the Circuit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v π #.%&6+#'$&66#)((2/"$&"L#@2,#$%+#+@@+($#2@# ( % ?
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6.6 Basic BJT Amplifier Configurations
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EXERCISE 6.42. =%+#0+'&L"+,#2@#$%+#)3*6&@&+,#&"#ET)3*6+#W?Kd#0+(&0+'#$2#62.+,#$%+#9&)'#(/,,+"$#$2#%)6@#&$'#2,&L&")6 7)6/+#&"#2,0+,#$2#,)&'+#$%+#&"*/$#,+'&'$)"(+#)"0#%+"(+#&"(,+)'+#$%+#@,)($&2"#2@# v '&L #$%)$#)**+),'#)$#$%+ &"*/$#2@#$%+#)3*6&@&+,#*,2*+,?#!"#)"#)$$+3*$#$2#3)&"$)&"#$%+#726$)L+#L)&"-#$%+#0+'&L"+,#0+(&0+'#$2 02/96+#$%+#7)6/+#2@# > - ? #D2,#$%+#"+.#0+'&L"-#0+$+,3&"+# > &" - # / v% - # > % - # / v - #)"0# Q v ? #!@#$%+#*+)U )3*6&$/0+#2@# v π #&'#$2#9+#6&3&$+0#$2#G#3]-#.%)$#),+#$%+#(2,,+'*2"0&"L#7)6/+'#2@# vt '&L #)"0# vt % #:.&$% $%+#62)0#(2""+($+0>_ Ans. G#U ΩH # ] KaP?G #]Z]H#a?G#U ΩH # ] WG?W #]Z]H# ] NM?f #]Z]H#KP#3]H#P?NN#]
431
432 Chapter 6 Bipolar Junction Transistors (BJTs)
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6.6 Basic BJT Amplifier Configurations
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!"30,&"$,/(#/3(&,-$0(;)$#,/*),30$,&"$,.*+3$,21, > 4 ,&2,/2)+,&"$,.*+3$,21, > &" ? !2,-$&$#'()$,&"$,.2+&*;$,;*(), / v% - ,4$,0$$,1#2',L(;<,X<^PT9V,&"*& v% d ]$E >d ]α $4 >-
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!"305,()/+3-();, > 4 ,#$-3/$0,&"$,.2+&*;$,;*(),9:,&"$,1*/&2#,( K e C I > 4 ) 5,4"(/",(0,&"$,0*'$,1*/% &2#,9:,4"(/", > &" ,(0,()/#$*0$-<,!"(0,72()&0,23&,*),()&$#$0&();,*-$%211,9$&4$$),;*(),*)-,()73& #$0(0&*)/$5, *, *-$%211, &"*&, &"$, -$0(;)$#, /*), $A$#/(0$, &"#23;", &"$, /"2(/$, 21, *), *77#27#(*&$ .*+3$,12#, > 4 ? !"$,23&73&,#$0(0&*)/$, > % ,/*),9$,123)-,1#2',&"$,/(#/3(&,(),L(;<,X<^PT9V,9:,()07$/&(2)Y >% d >-
433
434 Chapter 6 Bipolar Junction Transistors (BJTs) =1,*,+2*-,#$0(0&*)/$, > X ,(0,/2))$/&$-,*&,&"$,*'7+(1($#,23&73&5, / v ,/*),9$,123)-,*0, >X 5 / v d / v% 55555555555555555 >X e >% >>X 5 555555555555555555 5 d ] α 555555555555555 (4 e >4 >X e >> - || > X 5 d ] α 55555555555555555 (4 e >4
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4"(/",/23+-,"*.$,9$$),4#(&&$),-(#$/&+:,30();,MS<,TX&" > - || > X 5 × ] α 55555555555555555 5 Q v d 555555555555555555555 > &" e > '&L (4 e >4 K390&(&3&();,12#, > &" ,1#2',MS<,TX - || > X 5 Q v d ] β 55555555555555555555555555555555555555555555555555555 > '&L e ( β e K ) ( ( 4 e > 4 )
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!"305,12#,&"$,0*'$, v π 5,&"$,0(;)*+,*&,&"$,()73&,&$#'()*+,21,&"$,*'7+(1($#5, v $ - ,/*),9$,;#$*&$# &"*),12#,&"$,6M,*'7+(1($#,9:,&"$,1*/&2#, ( K e C I > 4 )? =2#'/33),&h+-#&"(6/0&"L#)#,+'&'$)"(+# > 4 #&"#$%+#+3&$$+,#2@#$%+#FE#)3*6&@&+,#,+'/6$'#&"#$%+ @2662.&"L#(%),)($+,&'$&('8 1. !"$,()73&,#$0(0&*)/$, > &" ,(0,()/#$*0$-,9:,&"$,1*/&2#, ( K e C I > 4 )? 2. =%+#726$)L+#L)&"#@,23#9)'+#$2#(266+($2,-# / v - #&'#,+0/(+0#91#$%+#@)($2,# ( K e C I > 4 )? 3. D2,#$%+#')3+#"2"6&"+),#0&'$2,$&2"-#$%+#&"*/$#'&L")6# v $ #()"#9+#&"(,+)'+0#91#$%+#@)($2, ( K e C I > 4 )? 4. =%+#27+,)66#726$)L+#L)&"#&'#6+''#0+*+"0+"$#2"#$%+#7)6/+#2@#β ? 5. =%+#%&L%5@,+V/+"(1#,+'*2"'+#&'#'&L"&@&()"$61#&3*,27+0#:)'#.+#'%)66#'++#&"#F%)*$+,#a>? W(&",&"$,$A/$7&(2),21,;*(),#$-3/&(2)5,&"$0$,/"*#*/&$#(0&(/0,#$7#$0$)&,7$#12#'*)/$,('7#2.$'$)&0< =)-$$-5,&"$,#$-3/&(2),(),;*(),(0,&"$,7#(/$,7*(-,12#,29&*()();,&"$,2&"$#,7$#12#'*)/$,('7#2.$'$)&0< =),'*):,/*0$0,&"(0,(0,*,;22-,9*#;*()`,(&,(0,&"$,3)-$#+:();,7"(+2027":,12#,&"$,30$,21,)$;*&(.$,1$$-% 9*/G<,!"*&,&"$,#$0(0&*)/$, > 4 ,()-3/$0,)$;*&(.$,1$$-9*/G,(),&"$,*'7+(1($#,/(#/3(&,/*),9$,0$$),9: #$1$#$)/$,&2,L(;<,X<^PT*VY,W"(+$,G$$7();, v $ ,/2)0&*)&5,*003'$,&"*&,12#,02'$,#$*02),&"$,/2++$/&2# /3##$)&,()/#$*0$0`,&"$,$'(&&$#,/3##$)&,*+02,4(++,()/#$*0$5,#$03+&();,(),*),()/#$*0$-,.2+&*;$,-#27 */#200, > 4 ? , !"30, &"$, $'(&&$#, .2+&*;$, #(0$05, *)-, &"$, 9*0$]$'(&&$#, .2+&*;$, -$/#$*0$0<, !"$, +*&&$# $11$/&, /*30$0, &"$, /2++$/&2#, /3##$)&, &2, -$/#$*0$5, /23)&$#*/&();, &"$, ()(&(*++:, *003'$-, /"*);$5, *) ()-(/*&(2),21,&"$,7#$0$)/$,21,)$;*&(.$,1$$-9*/G<,=),6"*7&$#,?O5,4"$#$,4$,0"*++,0&3-:,)$;*&(.$
6.6 Basic BJT Amplifier Configurations
435
1$$-9*/G, 12#'*++:5, 4$, 4(++, 1()-, &"*&, &"$, 1*/&2#, ( K e C I > 4 )- , 4"(/", *77$*#0, #$7$*&$-+:5, (0, &"$ a*'23)&,21,)$;*&(.$%1$$-9*/Gb,()-3/$-,9:, > 4 ? ,L()*++:5,4$,)2&$,&"*&,&"$,)$;*&(.$%1$$-9*/G */&(2),21, > 4 ,;(.$0,(&,&"$,)*'$,!"#$$!%-2!6!0!%'$#*0-%!(#($'0)!<
Example 6.18 D2,#$%+#FE#)3*6&@&+,#'*+(&@&+0#&"#ET)3*6+#W?Kd-#.%)$#7)6/+#2@# > 4 #&'#"++0+0#$2#,)&'+# > &" #$2#)#7)6/+ @2/,#$&3+'#$%)$#2@# > '&L_#Y&$%# > 4 #&"(6/0+0-#@&"0# / v%- # > % - # / v - #)"0# Q v ? #I6'2-#&@# vt π #&'#6&3&$+0#$2#G#3].%)$#),+#$%+#(2,,+'*2"0&"L#7)6/+'#2@# vt '&L #)"0# vt % _ Solution !2,29&*(), > &" d e > '&L d e × G d MP#UΩ 5,&"$,#$S3(#$-, > 4 ,(0,123)-,1#2' MP d ( β e K ) # ( ( 4 e > 4 )
W(&", β d KPP- , ( 4 e > 4 ! MPP#Ω
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436 Chapter 6 Bipolar Junction Transistors (BJTs)
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!"(0,$S3*&(2), ()-(/*&$0, &"*&, &"$, 2.$#*++, ;*()5, &"23;", +24$#,&"*),2)$5, /*), 9$, /+20$,&2, 2)$, (1 ( β e K )> X ,(0,+*#;$#,2#,/2'7*#*9+$,(),.*+3$,&2, > '&L ? ,!"(0,*;*(),/2)1(#'0,&"$,*/&(2),21,&"$,$'(&% &$#,12++24$#,(),-$+(.$#();,*,+*#;$,7#272#&(2),21, v '&L ,&2,*,+24%.*+3$-,+2*-,#$0(0&*)/$, > X ,$.$) &"23;", > '&L ,/*),9$,'3/",+*#;$#,&"*), > X<,!"$,G$:,72()&,(0,&"*&, > X ,(0,'3+&(7+($-,9:, ( β e K ) KW !"#*,)($&(+-#$%+#7)6/+#2@# / v% #.&66#9+#62.+,#$%)"-#9/$#(62'+#$2#/"&$1?#D2,#2"+#$%&"L-# ( % - #.%&(%#.+#%)7+ "+L6+($+0-#.2/60#3)U+# / v% d ( % ⁄ ( ( % e ( 4 )?#I6'2-#)'#)6,+)01#3+"$&2"+0-#$%+,+#3)1#9+#2$%+,#,+'&'$)"(+' :+?L?-#@2,#9&)'&"L#*/,*2'+'>#)$$)(%+0#$2#$%+#+3&$$+,?
441
442 Chapter 6 Bipolar Junction Transistors (BJTs) Rsig
Rsig / (b$1)
(b$1) re
vsig
$ %
(b$1) RL
re
$
vsig
$ %
RL
vo %
(a)
$ vo %
(b)
Figure 6.56 C&3*6+#+V/&7)6+"$#(&,(/&$'#@2,#$%+#+3&$$+,#@2662.+,#29$)&"+0#91#;'<#,+@6+($&"L#(4#)"0#>X#$2#$%+ 9)'+#'&0+-#)"0#;&<#,+@6+($&"L#v'&L#)"0#>'&L#$2#$%+#+3&$$+,#'&0+?#b2$+#$%)$#$%+#(&,(/&$#&"#;&<#()"#9+#29$)&"+0#@,23 $%)$#&"#;'<#91#'&3*61#0&7&0&"L#)66#,+'&'$)"(+'#91#T β e K>?
9$12#$,(&,(0,a7#$0$)&$-,&2,&"$,023#/$ X ,&2,&"$,9*0$,0(-$<,!"$,2.$#*++,.2+&*;$,;*() Q v ≡ v % ⁄ v '&L ,/*),9$,-$&$#'()$-,-(#$/&+:,*)-,.$#:,0('7+:,1#2',&"(0,/(#/3(&,9:,30();,&"$,.2+&*;$ -(.(-$#,#3+$<,!"$,#$03+&,(0,&"$,$A7#$00(2),12#, Q v ,*+#$*-:,;(.$),(),MS<,TX'&L ,1#2',&"$,9*0$,0(-$,&2 &"$,$'(&&$#,0(-$<,=),&"(0,#$1+$/&(2)5, v '&L ,-2$0,)2&,/"*);$5,93&, > '&L ,(0,-(.(-$-,9:, β e K<,!"305 4$,$(&"$#,#$1+$/&,&2,&"$,9*0$,0(-$,*)-,29&*(),&"$,/(#/3(&,(),L(;<,X<^XT*V,2#,#$1+$/&,&2,&"$,$'(&&$# 0(-$,*)-,29&*(),&"$,/(#/3(&,(),L(;<,X<^XT9V<,L#2',&"$,+*&&$#5, Q v ,/*),9$,123)-,*0, v >X Q v ≡ 555555%5 d 5555555555555555555555555555555555555555555555555555 5 v '&L > X e ( 4 e > '&L ⁄ ( β e K )
TX
J90$#.$,&"*&,&"(0,$A7#$00(2),(0,&"$,0*'$,*0,&"*&,(),MS<,TX'&L ,9:,&"$,1*/&2#, ( β e K ) ,9$12#$,a7#$0$)&();,(&,&2,&"$,+2*-,#$0(0&*)/$, > XbY,*) ('7$-*)/$,*)012#'*&(2),&"*&,"*0,&"$,0*'$,9311$#();,$11$/&< @&,&"(0,72()&,(&,(0,('72#&*)&,&2,)2&$,&"*&,*+&"23;",&"$,$'(&&$#,12++24$#,-2$0,)2&,7#2.(-$ .2+&*;$,;*(),(&,"*0,*,/3##$)&,;*(),21, β e K< Thévenin Representation of the Emitter-Follower Output I# 32,+# L+"+,)6# ,+*,+5 '+"$)$&2"# 2@# $%+# +3&$$+,5@2662.+,# 2/$*/$# &'# '%2."# &"# D&L?# W?Gd:)>?# \+,+# Q v% # &'# $%+# 27+,)66 2*+"5(&,(/&$# 726$)L+# L)&"# $%)$# ()"# 9+# 29$)&"+0# 91# '+$$&"L# > X d ∞ # &"# $%+# (&,(/&$# 2@# D&L? W?GW:9>-#)'#&66/'$,)$+0#&"#D&L?#W?Gd:9>?#=%+#,+'/6$#&'# Q v% d K?#=%+#2/$*/$#,+'&'$)"(+# > 2/$ #&'#5$GM G4(4!?8@,23# > % ? #=2#0+$+,3&"+# > 2/$ #.+#'+$# v '&L #$2#h+,2#:,)$%+,#$%)"#'+$$&"L# v $ #$2#h+,2>?#IL)&" .+#()"#/'+#$%+#+V/&7)6+"$#(&,(/&$#&"#D&L?#W?GW:9>#$2#02#$%&'-#)'#&66/'$,)$+0#&"#D&L?#W?Gd:(>?#Y+ '++#$%)$ > '&L > 2/$## d ( 4 e 55555555555 5 βeK
TX
6.6 Basic BJT Amplifier Configurations
443
Rsig / (b$1) Rout $ Gvo vsig
RL
$ %
vsig
vo
re $ %
%
Gvo " 1
$ vo " vsig %
(b)
(a)
Rsig / (b$1)
Rsig re E
Rsig Rout " re $ % b$1 (c)
Rsig Rout " re$% (b$1)
re vsig
$ %
RL
Rin " (b$1) (re$RL) (d)
Figure 6.57 ;'<#=%p7+"&"#,+*,+'+"$)$&2"#2@#$%+#2/$*/$#2@#$%+#+3&$$+,#@2662.+,?#:&>#B9$)&"&"L#Qv%#@,23#$%+ +V/&7)6+"$#(&,(/&$#&"#D&L?#W?GW:9>?#;)<#B9$)&"&"L#>2/$#@,23#$%+#+V/&7)6+"$#(&,(/&$#&"#D&L?#W?GW:9>#.&$%#v'&L#'+$#$2 h+,2?-;2<#=%+#+3&$$+,#@2662.+,#.&$%#>&"#)"0#>2/$#0+$+,3&"+0#'&3*61#91#622U&"L#&"$2#$%+#&"*/$#)"0#2/$*/$#$+,5 3&")6'-#,+'*+($&7+61?
D&")661-# .+# '%2.# &"# D&L?# W?Gd:0># $%+# +3&$$+,5@2662.+,# (&,(/&$# $2L+$%+,# .&$%# &$'# > &" # )"0 > 2/$ ? #B9'+,7+#$%)$# > &" #&'#0+$+,3&"+0#91#,+@6+($&"L# ( 4 #)"0# > X #$2#$%+#9)'+#'&0+#:91#3/6$&*615 &"L# $%+&,# 7)6/+'# 91# β e K>?# =2# 0+$+,3&"+# > 2/$ - # L,)9# %260# 2@# $%+# +3&$$+,# )"0# .)6U# :2,# 4/'$ 622Uj>#9)(U.),0#.%&6+# v '&L d P? #s2/#.&66#'++# ( 4 #&"#'+,&+'#.&$%# > '&L - #.%&(%#9+()/'+#&$#&'#&" $%+#9)'+#3/'$#9+#0&7&0+0#91#( β e K )? W$,)2&$,&"*&,3)+(G$,&"$,6M,*)-,6B,*'7+(1($#0,4$,0&3-($-,$*#+($#5,&"$,$'(&&$#,12++24$#,(0,!%? 3)(+*&$#*+<,!"(0,(0,'*)(1$0&$-,9:,&"$,1*/&,&"*&, > &" ,-$7$)-0,2), > X ,*)-, > 2/$ ,-$7$)-0,2), > '&L ?
Example 6.19 !$#&'#,+V/&,+0#$2#0+'&L"#)"#+3&$$+,#@2662.+,#$2#&3*6+3+"$#$%+#9/@@+,#)3*6&@&+,#2@#D&L?#W?Ge:(>?#C*+(&@1#$%+ ,+V/&,+0#9&)'#(/,,+"$# . * #)"0#$%+#3&"&3/3#7)6/+#$%+#$,)"'&'$2,# β #3/'$#%)7+?#X+$+,3&"+#$%+#3)T&3/3 )662.+0#7)6/+#2@# v B$C #&@# v π #&'#$2#9+#6&3&$+0#$2#G#3]#&"#2,0+,#$2#29$)&"#,+)'2")961#6&"+),#2*+,)$&2"?#Y&$% v '&L# d MPP #3]-#0+$+,3&"+#$%+#'&L")6#726$)L+#)$#$%+#2/$*/$#&@# > X #&'#(%)"L+0#$2#M#U Ω- #)"0#$2#P?G#U Ω?
444 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.19 continued
Rsig " 100 k& Ro " 10 & vo
vsig
$ % " 200 mV
RL " 1 k&
Rin " 100 k&
Figure 6.58 F&,(/&$#@2,#ET)3*6+#W?Ka?#
Solution =%+#+3&$$+,5@2662.+,#(&,(/&$#&'#'%2."#&"#D&L?#W?Gf?#=2#29$)&"# > % d KP#Ω- #.+#9&)'#$%+#$,)"'&'$2,#$2 29$)&"# ( 4 d KP#Ω? #=%/'+ KP#Ω d 55555,5 .* . * d M?G ,'@ !"$,()73&,#$0(0&*)/$, > &" ,4(++,9$ > &" d ( β e K ) ( ( 4 e > X ) KPP d ( β e K ) ( P?PK e K )
=%/'-#$%+#;<=#'%2/60#%)7+#)# β #.&$%#)#3&"&3/3#7)6/+#2@#af?#I#%&L%+,# β #.2/60#297&2/'61#9+#9+"+@&(&)6? =%+#27+,)66#726$)L+#L)&"#()"#9+#0+$+,3&"+0#@,23 v >X Q v ≡ 555555%5 d 5555555555555555555555555555555555555555 5 v '&L > '&L > X e ( 4 e 5555555555555555 5 (β e K) I''/3&"L# β d KPP -#$%+#7)6/+#2@# Q v #29$)&"+0#&'
Q v d P?G =%/'#.%+"# v '&L d MPP #3]-#$%+#'&L")6#)$#$%+#2/$*/$#.&66#9+#KPP#3]?#C&"(+#$%+#KPP#3]#)**+),'#)(,2''#$%+ K5U Ω #62)0-#$%+#'&L")6#)(,2''#$%+#9)'+Q+3&$$+,#4/"($&2"#()"#9+#@2/"0#@,23 v% v π d 555555 × ( 4
>X
KPP d 555555555555 × KP d K #3] KPPP !@# vt π d G#3]#$%+"# v '&L #()"#9+#&"(,+)'+0#91#)#@)($2,#2@#G-#,+'/6$&"L#&"# vt '&L d K#]? =2#29$)&"# v % #)'#$%+#62)0#&'#7),&+0-#.+#/'+#$%+#=%p7+"&"#+V/&7)6+"$#2@#$%+#+3&$$+,#@2662.+,-#'%2."#&" D&L?#W?Gd:)>#.&$%# Q v% d K #)"0 > '&L KPP > 2/$## d 555555555555 e ( 4 d 555555555 e P?PK d K#UΩ KPK βeK
6.6 Basic BJT Amplifier Configurations
445
$2#29$)&" > > X e > 2/$
X v % d v '&L 555555555555555555555
D2,# > X d M#UΩM MeK
v % d MPP#3] × 555555555555 d KNN?N#3]
)"0#@2,# > X d P?G#UΩP?G P?G e K
v % d MPP#3] × 5555555555555555 d WW?d#3]
EXERCISE 6.46 I"#+3&$$+,#@2662.+,#/$&6&h+'#)#$,)"'&'$2,#.&$%# β d KPP #)"0#&'#9&)'+0#)$# . - d G#3I?#!$#2*+,)$+'#9+5 $.++"#)#'2/,(+#%)7&"L#)#,+'&'$)"(+#2@#KP#U Ω #)"0#)#62)0#2@#K#U Ω? #D&"0# > &" - # Q v% - # > 2/$ - #)"0# Q v ? Y%)$#&'#$%+#*+)U#)3*6&$/0+#2@# v '&L #$%)$#,+'/6$'#&"# v π #%)7&"L#)#*+)U#)3*6&$/0+#2@#G#3]_#D&"0#$%+ ,+'/6$&"L#*+)U#)3*6&$/0+#)$#$%+#2/$*/$? Ans. KPK?G#U Ω H#K#]Z]H#KPe# Ω H#P?aK#]Z]H#K?K#]H#K#]
6.6.7 Summary and Comparisons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
446 Chapter 6 Bipolar Junction Transistors (BJTs) ?
TABLE 6.5 Characteristics of BJT Amplifiers)-#9-#(
> &" F2332" +3&$$+, :D&L?#W?GP>
( β e K )( 4
F2332" +3&$$+,#.&$%#
( β e K )( (4 e >4 )
/ v% ]CI >-
>% >-
/v ] C I ( > - || > X ) > - || > X 5 ] α 55555555555555555 (4
>4
CI >5 ] 55555555555555555555 K e CI >4
>-
] C I ( > - || > X ) 55555555555555555555555555555555 K e CI >4
Qv > - || > X 5 ] β 555555555555555555555555555555555555 > '&L e ( β e K )( 4 > - || > X 5 ] β 55555555555555555555555555555555555555555555555555555 > '&L e ( β e K ) ( ( 4 e > 4 )
> - || > X 5 ] α 55555555555555555 (4 e >4
:D&L?#W?GM>
F2332"#9)'+ :D&L?#W?GN>
(4
CI >-
>-
E3&$$+, @2662.+, :D&L?#W?GG>
( β e K )( (4 e >X )
K
(4
> || > > '&L e ( 4
C I ( > - || > X ) > - || > X 5 α 55555555555555555 (4
X 5 α 555555555555555555
>X 5555555555555555 >X e (4
>X 5555555555555555555555555555555555555555555555555555 5 > X e ( 4 e > '&L ⁄ ( β e K ) # Q v% d K
> '&L > 2/$ d ( 4 e 55555555555 5 βeK ' #
#D2,#$%+#&"$+,*,+$)$&2"#2@#>I-#/v%-#)"0#>%#,+@+,#$2#D&L?#W?ea? #=%+#;<=#2/$*/$#,+'&'$)"(+#(%#%)'#9++"#"+L6+($+0-#.%&(%#&'#*+,3&$$+0#&"#$%+#0&'(,+$+5(&,(/&$#)3*6&@&+,'#'$/0&+0#&"#$%&'#(%)*$+,?#D2,#&"$+L,)$+05(&,(/&$#)3*6&5
@&+,'#:F%)*$+,#d>-#( %#3/'$#)6.)1'#9+#$)U+"#&"$2#)((2/"$? E #C+$$&"L#β = ∞ ##(α = 1)#)"0#,+*6)(&"L8(4#.&$%#KZCI-#>-#.&$%#>1-#)"0#>4#.&$%#>B#,+'/6$'#&"#$%+#(2,,+'*2"0&"L#@2,3/6)'#@2,#ABCDE=#)3*6&@&+,'#:=)96+#G?e>?
6.7 Biasing in BJT Amplifier Circuits R*.();,0&3-($-,&"$,.*#(230,/2)1(;3#*&(2)0,21,BC!,*'7+(1($#05,4$,)24,*--#$00,&"$,('72#&*)& S3$0&(2),21,9(*0();,*)-,(&0,#$+*&(2)0"(7,&2,0'*++%0(;)*+,9$"*.(2#<,!"$,9(*0();,7#29+$',(0,&"*& 21,$0&*9+(0"();,*,/2)0&*)&,-/,/3##$)&,(),&"$,/2++$/&2#,21,&"$,BC!<,!"(0,/3##$)&,"*0,&2,9$,/*+/3% +*9+$5,7#$-(/&*9+$5,*)-,()0$)0(&(.$,&2,.*#(*&(2)0,(),&$'7$#*&3#$,*)-,&2,&"$,+*#;$,.*#(*&(2)0,() &"$,.*+3$,21,β,$)/23)&$#$-,*'2);,*)0(0&2#0,21,&"$,0*'$,&:7$<,@)2&"$#,('72#&*)&,/2)0(-$#% *&(2),(),9(*0,-$0(;),(0,+2/*&();,&"$,-/,9(*0,72()&,(),&"$,$- ]v-*,7+*)$,&2,*++24,12#,'*A('3' 23&73&,0(;)*+,04();,T0$$,&"$,-(0/300(2),(),K$/&(2),X<8) - ,(0,*+02,)2&,*,#$/2''$)-$-,*77#2*/"<,R$#$,&"$ &:7(/*++:,+*#;$,.*#(*&(2)0,(),&"$,.*+3$,21,β,*'2);,3)(&0,21,&"$,0*'$,-$.(/$,&:7$,4(++,#$03+&,() /2##$072)-();+:,+*#;$,.*#(*&(2)0,(),.-,*)-,"$)/$,(),+-*<
6.7 Biasing in BJT Amplifier Circuits
VCC
VCC
RB1
RB
RC
RC IC
IC IB $ RB2
VCE
VCE $
IB
VBE
VBE %
%
(b)
(a)
Figure 6.59 =.2#297&2/'#'(%+3+'#@2,#9&)'&"L#$%+#;<=8#;'<#91#@&T&"L# +)*H#;&<#91#@&T&"L#.)?#;2$%#,+'/6$ &" .&0+# 7),&)$&2"'# &"# .-# )"0# %+"(+# &"# +-*# )"0# $%+,+@2,+# ),+# (2"'&0+,+0# $2# 9+# R9)0?S# b+&$%+,# '(%+3+# &' ,+(233+"0+0?
6.7.1 The Classical Discrete-Circuit Bias Arrangement L(;3#$, X?5,>P<,=),*--(&(2)5,*,#$0(0&2#,>*,(0,/2))$/&$-,&2,&"$,$'(&&$#< VCC
VBB " VCC
%
R2 R1 $ R2
& RC
RC
R1
VCC
IB RB " R1 $ R2
R2
RE
(a)
L
IC
IE RE
(b)
Figure 6.60 F6)''&()6# 9&)'&"L# @2,# ;<='# /'&"L# )# '&"L6+# *2.+,# '/**618# ;'<# (&,(/&$H# ;&<# (&,(/&$# .&$%# $%+ 726$)L+#0&7&0+,#'/**61&"L#$%+#9)'+#,+*6)(+0#.&$%#&$'#=%p7+"&"#+V/&7)6+"$?
L(;3#$,X
>M 5+ + )) = 5555555555555555 > K + > M --
TX
447
448 Chapter 6 Bipolar Junction Transistors (BJTs) >K >M 5 > ) = 5555555555555555 >K + >M
TX
!"$,/3##$)&,.*,/*),9$,-$&$#'()$-,9:,4#(&();,*,q(#/""211,+227,$S3*&(2),12#,&"$,9*0$]$'(&&$#] ;#23)-,+2275,+*9$+$-,F5,*)-,0390&(&3&();, . ) = . * ⁄ ( β + K ) 8
+ )) ] + )* 5 . * = 555555555555555555555555555555555555555 >* + >) ⁄ ( β + K )
TX
!2,'*G$,.*,()0$)0(&(.$,&2,&$'7$#*&3#$,*)-, β,.*#(*&(2)5?N,4$,-$0(;),&"$,/(#/3(&,&2,0*&(01:,&"$ 12++24();,&42,/2)0*()&0Y
+)) #!#+)* > > *# ! 55555555555 # )5 β+K
TX
62)-(&(2), TX-, *)-, &"$, /2++$/&2#]9*0$, H3)/&(2), T+-)V<, J), &"$, 2&"$#, "*)-5, 4$, 4*)&, &"$, .2+&*;$ */#200,>-,&2,9$,+*#;$,(),2#-$#,&2,29&*(),"(;",.2+&*;$,;*(),*)-,+*#;$,0(;)*+,04();,T9$12#$,*)% 0(0&2#,/3&211V<,W$,*+02,4*)&,+-),T2#,+-*V,&2,9$,+*#;$,&2,7#2.(-$,*,+*#;$,0(;)*+,04();,T9$12#$ *)0(0&2#,0*&3#*&(2)V<,!"305,*0,(0,&"$,/*0$,(),*):,-$0(;)5,4$,"*.$,* 0$&,21,/2)1+(/&();,#$S3(#$% '$)&05,*)-,&"$,02+3&(2),'30&,9$,*,*-$%211<,@0,* #3+$,21,&"3'95,2)$,-$0(;)0,12#,+)),*923& K K K 555 +-- - + ,T2#,+ V,*923&, 555 +-- - ,*)-,. > ,*923&, 555 +-- ? -) -* - N N N 62)-(&(2),TX),0'*++<,!"(0,(),&3#),(0,*/"($.$-,9:,30();,+24,.*+3$0,12#,>?,*)-,>P<,F24$#,.*+3$0,12#,>? *)-,>P5,"24$.$#5,4(++,'$*),*,"(;"$#,/3##$)&,-#*(),1#2',&"$,724$#,0377+:5,*)-,4(++,#$03+&,() *, +24$#();, 21, &"$, ()73&, #$0(0&*)/$, 21, &"$, *'7+(1($#, T(1, &"$, ()73&, 0(;)*+, (0, /237+$-, &2, &"$ 9*0$V5?E,4"(/",(0,&"$,*-$%211,().2+.$-,(),&"(0,7*#&,21,&"$,-$0(;)<,=&,0"23+-,9$,)2&$-,&"*& /2)-(&(2),TX?, *)-, >P 03/",&"*&,&"$(#,/3##$)&,(0,(),&"$,#*);$,21,.*,&2,O.*< L3#&"$#,()0(;"&,#$;*#-();,&"$,'$/"*)(0',9:,4"(/",&"$,9(*0,*##*);$'$)&,21,L(;<,X$0, &"$, -/, $'(&&$#, T*)-, "$)/$, /2++$/&2#V, /3##$)&, (0, 29&*()$-, 9:, /2)0(-$#();, &"$, 1$$-9*/G */&(2),7#2.(-$-,9:,>*<,62)0(-$#,&"*&,12#,02'$,#$*02),&"$,$'(&&$#,/3##$)&,()/#$*0$0<,!"$,.2+&*;$ -#27,*/#200,>*5,*)-,"$)/$,+*,4(++,()/#$*0$,/2##$072)-();+:<,Q245,(1,&"$,9*0$,.2+&*;$,(0,-$&$#% '()$-,7#('*#(+:,9:,&"$,.2+&*;$,-(.(-$#,>?5,>P5,4"(/",(0,&"$,/*0$,(1,>),(0,0'*++5,(&,4(++,#$'*() /2)0&*)&5, *)-, &"$, ()/#$*0$, (), +*, 4(++, #$03+&, (), *, /2##$072)-();, -$/#$*0$, (), +)*<, !"(0, (), &3#) #$-3/$0,&"$,/2++$/&2#,T*)-,$'(&&$#V,/3##$)&5,*,/"*);$,27720(&$,&2,&"*&,2#(;()*++:,*003'$-<,!"30 >*,7#2.(-$0,*,!4C'?$F48G445#'EP,*/&(2),&"*&,0&*9(+(>$0,&"$,9(*0,/3##$)&<,!"(0,0"23+-,#$'()-,&"$ #$*-$#,21,&"$,#$0(0&*)/$,>4,&"*&,4$,()/+3-$-,(),&"$,$'(&&$#,+$*-,21,&"$,6M,*'7+(1($#,(),K$/&(2) X
;&)'#0+'&L"#'++U'#$2#'$)9&6&h+#+&$%+,#.*#2,#.-#'&"(+#.-#=#α.*#)"0#α#7),&+'#7+,1#6&$$6+?#=%)$#&'-#)#'$)96+#.* .&66#,+'/6$#&"#)"#+V/)661#'$)96+#.--#)"0#7&(+#7+,')? Kf !@#$%+#&"*/$#'&L")6#&'#(2/*6+0#$2#$%+#$,)"'&'$2,#9)'+-#$%+#$.2#9&)'#,+'&'$)"(+'#>?,*)-8>P#+@@+($&7+61#)**+), &"#*),)66+6#9+$.++"#$%+#9)'+#)"0#L,2/"0?#=%/'-#62.#7)6/+'#@2,#>?,*)-8>P,.&66#,+'/6$#&"#62.+,&"L#>&"? Kd
6.7 Biasing in BJT Amplifier Circuits
449
Example 6.20 Y+#.&'%#$2#0+'&L"#$%+#9&)'#"+$.2,U#2@#$%+#)3*6&@&+,#&"#D&L?#W?WP#$2#+'$)96&'%#)#(/,,+"$#.*#=#K#3I#/'&"L#) *2.+,#'/**61#+--# =# +KM#]?#=%+#$,)"'&'$2,#&'#'*+(&@&+0#$2#%)7+#)#"23&")6#β#7)6/+#2@#KPP?
Solution Y+#'%)66#@2662.#$%+#,/6+#2@#$%/39#3+"$&2"+0#)927+#)"0#)662()$+#2"+5$%&,0#2@#$%+#'/**61#726$)L+#$2#$%+ 726$)L+#0,2*#)(,2''#>M#)"0#)"2$%+,#2"+5$%&,0#$2#$%+#726$)L+#0,2*#)(,2''#>- -#6+)7&"L#2"+5$%&,0#@2,#*2''&96+ "+L)$&7+#'&L")6#'.&"L#)$#$%+#(266+($2,?#=%/'+ ) = +e#] + * = e ] + )* #!#N?N#] *)-,>*,(0,-$&$#'()$-,1#2' + N?N > * = 55555*5 = 5555555 = N?N#UΩ .* K L#2',&"$,-(0/300(2),*92.$,4$,0$+$/&,*,.2+&*;$,-(.(-$#,/3##$)&,21, P?K. * = P?K × K = P?K#3I? ,Q$;+$/&(); &"$,9*0$,/3##$)&5,4$,1()KM > K + > M = 5555555 = KMP#UΩ P?K *)>M 55555555555555555 5+ = e#] > K + > M -!"30,>P,=,8O,GΩ,*)-,>?,=,EO,GΩ<, @&,&"(0,72()&5,(&,(0,-$0(#*9+$,&2,1()-,*,'2#$,*//3#*&$,$0&('*&$,12#,.*5,&*G();,()&2,*//23)&,&"$,)2)>$#2 9*0$,/3##$)&<,c0();,MS<,TX*,1#2',\<\,GΩ,9:,&"$,'*;)(% &3-$,21,&"$,0$/2)-,&$#',(),&"$,-$)2'()*&2#,TO*,(),&"(0,/*0$ 423+-,9$,>*,=,\,GΩ5,4"(/",#$03+&0,(),.*,=,? ?,=,E,GΩ,*)-,>P,=,8,GΩ<,W$,0"*++,#$1$#,&2,&"$,/(#/3(&,30();,&"$0$,+*&&$#,.*+3$0,*0 -$0(;),P5,12#,4"(/",&"$,*/&3*+,.*+3$,21,.*,30();,&"$,()(&(*+,.*+3$,21,>*,21,\<\,GΩ,4(++,9$ e ] P?d . * = 555555555555555555555555555 = P?aa#!#K#3I N?N + P?PMd ?D
I6$%2/L%#,+0/(&"L# >*88 ,+'$2,+'# .*#$2#$%+#0+'&L"#7)6/+#2@# ?,'@-#&$#02+'#"2$#'267+#$%+#*,296+3#2@#$%+ 0+*+"0+"(+#2@#$%+#7)6/+#2@#.*#2"#β. C++#ET+,(&'+#W?ed? Ka
450 Chapter 6 Bipolar Junction Transistors (BJTs)
Example 6.20 continued
=),&"(0,/*0$5,-$0(;),P5,4$,)$$-,)2&,/"*);$,&"$,.*+3$,21,>*< D&")661-#$%+#7)6/+#2@#>-#()"#9+#0+$+,3&"+0#@,23# KM ] + > - = 55555555555555555-5 .C/9'$&$/$&"L# . - = α . * #= P?aa × K = P?aa#3I#!#K#3I #,+'/6$'-#@2,#92$%#0+'&L"'-#&" KM ] f > - = 555555555555555 = e#UΩ K
EXERCISE 6.47 D2,#0+'&L"#K#&"#ET)3*6+#W?MP-#()6(/6)$+#$%+#+T*+($+0#,)"L+#2@#.*#&@#$%+#$,)"'&'$2,#/'+0#%)'#β#&"#$%+ ,)"L+#2@#GP#$2#KGP?#ET*,+''#$%+#,)"L+#2@#.*#)'#)#*+,(+"$)L+#2@#$%+#"23&")6#7)6/+#:.*#!#K#3I>#295 $)&"+0#@2,#β =#KPP?#J+*+)$#@2,#0+'&L"#M? Ans. D2,#0+'&L"#K8#P?ae#3I#$2#K?Pe#3I-#)#KPo#,)"L+H#@2,#0+'&L"#M8#P?afe#3I#$2#P?aaG#3I-#)#K?Ko ,)"L+?
6.7.2 A Two-Power-Supply Version of the Classical Bias Arrangement @, 02'$4"*&, 0('7+$#, 9(*0, *##*);$'$)&, (0, 7200(9+$, (1, &42, 724$#, 0377+($0, *#$, *.*(+*9+$5, *0 0"24),(),L(;<,X
+ ** ] + )* . * = 5555555555555555555555555555555555555555 , >* + >) ⁄ ( β + K )
TX
Figure 6.61 ;&)'&"L# $%+# ;<=# /'&"L# $.2# *2.+,# '/**6&+'?# J+'&'$2,# >)# &' "++0+0#2"61#&@#$%+#'&L")6#&'#$2#9+#()*)(&$&7+61#(2/*6+0#$2#$%+#9)'+?#B$%+,5 .&'+-#$%+#9)'+#()"#9+#(2""+($+0#0&,+($61#$2#L,2/"0-#2,#$2#)#L,2/"0+0#'&L")6 '2/,(+-#,+'/6$&"L#&"#)632'$#$2$)6#β 5&"0+*+"0+"(+#2@#$%+#9&)'#(/,,+"$?
6.7 Biasing in BJT Amplifier Circuits
!"(0,$S3*&(2),(0,(-$)&(/*+,&2,MS<,TX),/*),9$,$+('()*&$-,*+&2;$&"$#< J),&"$,2&"$#,"*)-5,(1,&"$,()73&,0(;)*+,(0,&2,9$,/237+$-,&2,&"$,9*0$5,&"$),>),(0,)$$-$-<,W$,0"*++ 0&3-:,/2'7+$&$,/(#/3(&0,21,&"$,.*#(230,BC!,*'7+(1($#,/2)1(;3#*&(2)0,(),K$/&(2),X
EXERCISE D6.48 =%+#9&)'#),,)"L+3+"$#2@#D&L?#W?WK#&'#$2#9+#/'+0#@2,#)#(2332"59)'+#)3*6&@&+,?#X+'&L"#$%+#(&,(/&$ $2#+'$)96&'%#)#0(#+3&$$+,#(/,,+"$#2@#K#3I#)"0#*,27&0+#$%+#%&L%+'$#*2''&96+#726$)L+#L)&"#.%&6+#)65 62.&"L#@2,#)#3)T&3/3#'&L")6#'.&"L#)$#$%+#(266+($2,#2@#±M#]?#^'+#+KP5]#)"0#−G5]#*2.+,#'/**6&+'? Ans. >),=,O`,>*,=,8<\,GΩ`,>-,=,E<8,GΩ
6.7.3 Biasing Using a Collector-to-Base Feedback Resistor L(;3#$, X),/2))$/&$-,9$&4$$),&"$,/2++$/% &2#,*)-,&"$,9*0$<,U$0(0&2#,>),7#2.(-$0,)$;*&(.$,1$$-9*/G5,4"(/","$+70,&2,0&*9(+(>$,&"$,9(*0 72()&,21,&"$,BC!<,W$,0"*++,0&3-:,1$$-9*/G,12#'*++:,(),6"*7&$#,?O< @)*+:0(0,21,&"$,/(#/3(&,(0,0"24),(),L(;<,X
+ -- = . * > - + . ) > ) + + )* .* 5 > + + )* = . * > - + 55555555555 β+K ) !"30,&"$,$'(&&$#,9(*0,/3##$)&,(0,;(.$),9:
+ -- ] + )* 5 . * = 555555555555555555555555555555555555555 >- + >) ⁄ ( β + K )
(a)
iE is sum on top and on bottom all can do KCL
TX
(b)
Figure 6.62 ;'<#I#(2332"5+3&$$+,#$,)"'&'$2,#)3*6&@&+,#9&)'+0#91#)#@++09)(U#,+'&'$2,#>)?#;&<#I")61'&'#2@ $%+#(&,(/&$#&"#;'
451
452 Chapter 6 Bipolar Junction Transistors (BJTs) =&,(0,()&$#$0&();,&2,)2&$,&"*&,&"(0,$S3*&(2),(0,(-$)&(/*+,&2,MS<,TX-,#$7+*/$0,>*<,=&,12++240,&"*&,&2 29&*(), *, .*+3$, 21, .*, &"*&, (0,()0$)0(&(.$, &2, .*#(*&(2),21, β5,4$, 0$+$/&, > ) ⁄ ( β + K ) #*#> - ?,Q2&$5 "24$.$#5,&"*&,&"$,.*+3$, 21,>),-$&$#'()$0,&"$,*++24*9+$,)$;*&(.$,0(;)*+, 04();,*&,&"$,/2++$/&2# 0()/$
>) 5, + -) = . ) > ) = . * 55555555555 β+K
TX
EXERCISE D6.49 X+'&L"#$%+#(&,(/&$#2@#D&L?#W?WM#$2#29$)&"#)#0(#+3&$$+,#(/,,+"$#2@#K#3I-#3)T&3/3#L)&"-#)"0#)#±M5] '&L")6#'.&"L#)$#$%+#(266+($2,H#$%)$#&'-#0+'&L"#@2,#+-*#=#+M?N#]?#[+$#+--#=#KP#]#)"0#β# =#KPP? Ans. >),=,?XP,GΩ`,>-,=,N),=,?XO,GΩ,*)-,>-,=,N<^,GΩ<,!"(0,#$03+&0,(),.*,=,?
6.7.4 Biasing Using a Constant-Current Source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β,.*+3$05,4$,/*) )$;+$/&,&"$(#,9*0$,/3##$)&0<,!"30,&"$,/3##$)&,&"#23;",V?,4(++,9$,*77#2A('*&$+:,$S3*+,&2,.UML5
+ -- ] ( ] + ** ) ] + )* 5 . JED = 55555555555555555555555555555555555555555555555 >
0.7
TX?OV
VCC IREF
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V Q1
$ VBE %
Q2
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(b)
Figure 6.63 ;'<#I#;<=#9&)'+0#/'&"L#)#(2"'$)"$5(/,,+"$#'2/,(+#.?#;&<#F&,(/&$#@2,#&3*6+3+"$&"L#$%+#(/,,+"$ '2/,(+#.?
6.8 Discrete-Circuit BJT Amplifiers
Q245,0()/$,V?,*)-,VP,"*.$,&"$,0*'$,+)*5,&"$(#,/2++$/&2#,/3##$)&0,4(++,9$,$S3*+5,#$03+&();,(),
+ -- + + ** ] + )* . = . JED = 55555555555555555555555555555555555555 >
TX??V
Q$;+$/&();,&"$,M*#+:,$11$/&,(),VP5,&"$,/2++$/&2#,/3##$)&,4(++,#$'*(),/2)0&*)&,*&,&"$,.*+3$ ;(.$),9:,&"(0,$S3*&(2),*0,+2);,*0,VP,#$'*()0,(),&"$,*/&(.$,#$;(2)<,!"(0,/*),9$,;3*#*)&$$-,9: G$$7();,&"$,.2+&*;$,*&,&"$,/2++$/&2#5,+5,;#$*&$#,&"*),&"*&,*&,&"$,$'(&&$#,T−+**V,9:,*&,+$*0&,O<\_< !"$,/2))$/&(2),21,V?,*)-,VP,(),L(;<,X
EXERCISE 6.50 D2,#$%+#(&,(/&$#&"#D&L?#W?WN:)>#.&$%#+--#=#KP#]-#.#=#K#3I-#β#=#KPP-#>)#=#KPP#UΩ-#)"0#>-#=#d?G#UΩ-#@&"0 $%+#0(#726$)L+#)$#$%+#9)'+-#$%+#+3&$$+,-#)"0#$%+#(266+($2,?#D2,#+**#=#KP#]-#)"0#"+L6+($&"L#9)'+#(/,,+"$'@&"0#$%+#,+V/&,+0#7)6/+#2@#>#&"#2,0+,#@2,#$%+#(&,(/&$#2@#D&L?#W?WN:9>#$2#&3*6+3+"$#$%+#(/,,+"$#'2/,(+#.? Ans. −K#]H#−K?d#]H#+M?W#]H#Ka?N#UΩ
6.8 Discrete-Circuit BJT Amplifiers Y&$%#2/,#'$/01#2@#;<=#)3*6&@&+,#9)'&('#(23*6+$+-#.+#"2.#*/$#+7+,1$%&"L#$2L+$%+,#91#*,+'+"$5 &"L#*,)($&()6#(&,(/&$'#@2,#0&'(,+$+5(&,(/&$#)3*6&@&+,'?#=%+'+#(&,(/&$'-#.%&(%#/$&6&h+#$%+#)3*6&@&+, (2"@&L/,)$&2"'#'$/0&+0#&"#C+($&2"#W?W#)"0#2"+#2@#$%+#9&)'&"L#3+$%20'#2@#C+($&2"#W?d-#()"#9+ )''+396+0#/'&"L#2@@5$%+5'%+6@#0&'(,+$+#$,)"'&'$2,'-#,+'&'$2,'-#)"0#()*)(&$2,'?#=%2/L%#*,)($&()6 )"0#(),+@/661#'+6+($+0#$2#&66/'$,)$+#'23+#&3*2,$)"$#*2&"$'-#$%+#(&,(/&$'#*,+'+"$+0#&"#$%&'#'+($&2" '%2/60#9+#,+L),0+0#)'#+T)3*6+'#2@#0&'(,+$+5(&,(/&$-#9&*26),5$,)"'&'$2,#)3*6&@&+,'?#!"0++0-#$%+,+ &'# )# L,+)$# 7),&+$1# 2@# '/(%# (&,(/&$'-# )# "/39+,# 2@# .%&(%# ),+# +T*62,+0# &"# $%+# +"052@5(%)*$+, *,296+3'? !"#$%&'#'+($&2"#.+#*,+'+"$#)#'+,&+'#2@#+T+,(&'+#*,296+3'-#ET+,(&'+'#W?GK#$2#W?GG-#.%&(%#),+ (),+@/661#0+'&L"+0#$2#&66/'$,)$+#&3*2,$)"$#)'*+($'#2@#$%+#)3*6&@&+,#(&,(/&$'#'$/0&+0?#=%+'+#+T+,5 (&'+'#),+#)6'2#&"$+"0+0#$2#+")96+#$%+#,+)0+,#$2#'++#32,+#(6+),61#$%+#0&@@+,+"(+'#9+$.++"#$%+#7),5 &2/'#(&,(/&$#(2"@&L/,)$&2"'?#Y+#'$,2"L61#/,L+#$%+#,+)0+,#$2#'267+#$%+'+#+T+,(&'+'?#I'#/'/)6-#$%+ )"'.+,'#),+#*,27&0+0?
6.8.1 The Basic Structure D&L/,+#W?We#'%2.'#$%+#9)'&(#(&,(/&$#$%)$#.+#'%)66#/$&6&h+#$2#&3*6+3+"$#$%+#7),&2/'#(2"@&L/,)5 $&2"'#2@#0&'(,+$+#;<=#)3*6&@&+,'?#I32"L#$%+#7),&2/'#9&)'&"L#'(%+3+'#*2''&96+#@2,#0&'(,+$+#;<= )3*6&@&+,'#:C+($&2"#W?d>-#.+#%)7+#'+6+($+0-#@2,#'&3*6&(&$1#)"0#+@@+($&7+"+''-#$%+#2"+#+3*621&"L (2"'$)"$5(/,,+"$#9&)'&"L?#D&L/,+#W?We#&"0&()$+'#$%+#0(#(/,,+"$'#&"#)66#9,)"(%+'#)"0#$%+#0(#726$5 )L+'#)$#)66#"20+'?#Y+#'%2/60#"2$+#$%)$#2"+#.2/60#.)"$#$2#'+6+($#)#6),L+#7)6/+#@2,#>)#&"#2,0+,#$2 U++*#$%+#&"*/$#,+'&'$)"(+#)$#$%+#9)'+#6),L+?#\2.+7+,-#.+#)6'2#.)"$#$2#6&3&$#$%+#0(#726$)L+#0,2* )(,2''#>)#)"0#+7+"#32,+#&3*2,$)"$61#$%+#7),&)9&6&$1#2@#$%&'#0(#726$)L+#,+'/6$&"L#@,23#$%+#7),&)5 $&2"#&"# β#7)6/+'#)32"L#$,)"'&'$2,'#2@#$%+#')3+#$1*+?#=%+#0(#726$)L+#+)#0+$+,3&"+'#$%+#)662.5 )96+#"+L)$&7+#'&L")6#'.&"L#)$#$%+#(266+($2,?##
453
454 Chapter 6 Bipolar Junction Transistors (BJTs) VCC IC " #I RC VC " VCC % #RC I VB " %
IB " I'(" $ 1)
IRB "$1
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VBE
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VE " %
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BE
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EXERCISE 6.51 F2"'&0+,#$%+#(&,(/&$#2@#D&L?#W?We#@2,#$%+#()'+#+--#=#+**#=#KP#]-#.#=#K#3I-#>)#=#KPP#UΩ-#>-#=#f#UΩ)"0#β#=#KPP?#D&"0#)66#0(#(/,,+"$'#)"0#726$)L+'?#Y%)$#),+#$%+#)662.)96+#'&L")6#'.&"L'#)$#$%+#(266+($2, &"#92$%#0&,+($&2"'_#\2.#02#$%+'+#7)6/+'#(%)"L+#)'#β#&'#(%)"L+0#$2#GP_#=2#MPP_#D&"0#$%+#7)6/+'#2@ $%+#;<=#'3)665'&L")6#*),)3+$+,'#)$#$%+#9&)'#*2&"$#:.&$%#β# =#KPP>?#=%+#E),61#726$)L+#+/#=#KPP#]? Ans. C++#D&L?#EW?GK?#C&L")6#'.&"L8#@2,# β# =#KPP-#+f#]-#QN?e#]H#@2,# β#=#GP-#+f#]-#Qe?e#]H#@2, β = MPP-#+f ]-#QM?a#]? $10 V C
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6.8 Discrete-Circuit BJT Amplifiers
455
6.8.2 The Common-Emitter (CE) Amplifier @0, '$)&(2)$-, (), K$/&(2), X$#2,('7$-*)/$`,(<$<5,(),$11$/&5,*,0"2#&,/(#/3(&V,*&,*++,0(;)*+ 1#$S3$)/($0,21,()&$#$0&<,=),&"(0,4*:5,&"$,$'(&&$#,0(;)*+,/3##$)&,7*00$0,&"#23;",-*,&2,;#23)*)-,&"30,#H"'BB4B,&"$,23&73&,#$0(0&*)/$,21,&"$,/3##$)&,023#/$,.,T*)-,*):,2&"$#,/(#/3(&,/2'% 72)$)&, &"*&, '(;"&, 9$, /2))$/&$-, &2, &"$, $'(&&$#V`, "$)/$, -* (0, /*++$-, *, &94'((- )'4')#$*%< J9.(230+:5,&"$,+24$#,&"$,0(;)*+,1#$S3$)/:5,&"$,+$00,$11$/&(.$,&"$,9:7*00,/*7*/(&2#,9$/2'$0< !"(0,(003$,4(++,9$,0&3-($-,(),K$/&(2),D
RC
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ro
rp
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Ro = RC ||ro
(b) Figure 6.65 ;'<#I#(2332"5+3&$$+,#)3*6&@&+,#/'&"L#$%+#'$,/($/,+#2@#D&L?#W?We?#;&<#EV/&7)6+"$#(&,(/&$ 29$)&"+0#91#,+*6)(&"L#$%+#$,)"'&'$2,#.&$%#&$'#%19,&05π#320+6?
456 Chapter 6 Bipolar Junction Transistors (BJTs) (0, */&();, *0, *, 7$#1$/&, 0"2#&, /(#/3(&, *)-, &"30, (0, $0&*9+(0"();, *, >$#2, 0(;)*+, .2+&*;$, *&, &"$ $'(&&$#< =), 2#-$#,)2&, &2,-(0&3#9,&"$,-/,9(*0, /3##$)&0,*)-,.2+&*;$05,&"$,0(;)*+,&2,9$,*'7+(1($-5 0"24), *0, *, .2+&*;$, 023#/$, v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vE5,(0,/237+$-,&2,&"$,+2*-,#$0(0&*)/$,>X,.(* *)2&"$#,/237+();,/*7*/(&2#,--P<,W$,0"*++,*003'$,&"*&,--P,*+02,*/&0,*0,*,7$#1$/&,0"2#&,/(#/3(& *&,*++,0(;)*+,1#$S3$)/($0,21,()&$#$0&`,&"30,&"$,23&73&,.2+&*;$, v%,=, vE<,Q2&$,&"*&,>X,/*),9$,*) */&3*+,+2*-,#$0(0&2#,&2,4"(/",&"$,*'7+(1($#,(0,#$S3(#$-,&2,7#2.(-$,(&0,23&73&,.2+&*;$,0(;)*+5,2# (&,/*),9$,&"$,()73&,#$0(0&*)/$,21,*,0390$S3$)&,*'7+(1($#,0&*;$,(),/*0$0,4"$#$,'2#$,&"*),2)$ 0&*;$,21,*'7+(1(/*&(2),(0,)$$-$-<,TW$,4(++,0&3-:,'3+&(0&*;$,*'7+(1($#0,(),6"*7&$#,E
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!@# > ) ! ( π #.+#()"#"+L6+($#&$'#+@@+($-#)"0#.+#),+#9)(U#$2#$%+#'&3*6+,#(&,(/&$#2@#D&L?#W?GP:9> )"0# $%+# @2,3/6)'# 0+,&7+0# &"# C+($&2"# W?W?N?# =%2'+# @2,3/6)'-# .&$%# ( % # "+L6+($+0-# .+,+# *,+5 '+"$+0#&"#$%+#FE#+"$,1#&"#=)96+#W?e? !@# > ) #&'#"2$#3/(%#L,+)$+,#$%)"# ( π -#$%+"#&$#3/'$#9+#$)U+"#&"$2#)((2/"$#&"#$%+#)")61'&'?#=%&' &'#)#'&3*6+#$)'U-#)"0#.+#/,L+#$%+#,+)0+,'#$2#4/'$#.2,U#$%+&,#.)1#$%,2/L%#$%+#(&,(/&$#,)$%+, $%)"# ,+61&"L#2"#3+32,&h+0#@2,3/6)'?#I'# )#(%+(U-# %2.+7+,-#$%+,+# &'#)# '&3*6+# )**,2)(%#$2 )0)*$#$%+#FE#@2,3/6)'#2@#=)96+#W?e#$2#$%+#()'+#)$#%)"08#I**61#$%+#=%p7+"&"#$%+2,+3#$2#$%+ "+$.2,U# (23*2'+0# 2@# v '&L - # > '&L - # )"0# > ) - # $%/'# ,+0/(&"L# &$# $2# )# L+"+,)$2,# v′'&L d ( > ) ⁄ ( > ) e > '&L ) ) v '&L #)"0#)#,+'&'$)"(+# >′ '&L d > '&L || > ) ? #b2.#$%+#@2,3/6)'#&"#$%+#FE#+"$,1#&" =)96+#W?e#()"#9+#(%)"L+0#)'#@2662.'8#J+*6)(+#$%+#+T*,+''&2"#@2,# > &" #91#$%)$#&"#EV?#:W?KKM>H 3/6$&*61#$%+#+T*,+''&2"#@2,# Q v #91#$%+#@)($2,# > ) ⁄ ( > ) e > '&L ) H #)"0#,+*6)(+# > '&L #&"#$%)$#+T*,+'5 '&2"#91# ( > '&L || > ) )?
6.8 Discrete-Circuit BJT Amplifiers
EXERCISE 6.52 F2"'&0+,#$%+#FE#)3*6&@&+,#2@#D&L?#W?WG:)>#.%+"#9&)'+0#)'#&"#ET+,(&'+#W?GK?#!"#*),$&(/6),-#,+@+,#$2 D&L? EW?GK#@2,#$%+#9&)'#(/,,+"$'#)"0#$%+#7)6/+'#2@#$%+#+6+3+"$'#2@#$%+#;<=#320+6#)$#$%+#9&)'#*2&"$?#E7)65 /)$+#>&"#:.&$%2/$#)"0#.&$%#>)#$)U+"#&"$2#)((2/"$>-#/v%#:.&$%2/$#)"0#.&$%#(%#$)U+"#&"$2#)((2/"$>-#)"0 >2#:.&$%2/$#)"0#.&$%#(%#$)U+"#&"$2#)((2/"$>?#D2,#>X#=#G#UΩ-#@&"0#/v?#!@#>'&L#=#G#UΩ-#@&"0#$%+#27+,)66 726$)L+#L)&"#Qv?#!@#$%+#'&"+5.)7+# vπ#&'#$2#9+#6&3&$+0#$2#G#3]#*+)U-#.%)$#&'#$%+#3)T&3/3#)662.+0 *+)U#)3*6&$/0+#2@#v'&L#)"0#$%+#(2,,+'*2"0&"L#*+)U#)3*6&$/0+#2@#v%_ Ans. P<^,GΩ5,P<8,GΩ`,]\PO,_o_5,]PDX,_o_`,E,GΩ5,N<8,GΩ`,]??D,_o_`,]\D,_o_`,?^ '_`,O
6.8.3 The Common-Emitter Amplifier with an Emitter Resistance I'#0+32"'$,)$+0#&"#C+($&2"#W?W?e-#)#"/39+,#2@#9+"+@&(&)6#,+'/6$'#()"#9+#29$)&"+0#91#(2""+($5 &"L#)#,+'&'$)"(+# > 4 #&"#$%+#+3&$$+,#2@#$%+#$,)"'&'$2,?#=%&'#&'#'%2."#&"#D&L?#W?WW:)>#.%+,+# > 4 #&'2@# (2/,'+-# /"91*)''+0?# D&L/,+# W?WW:9># '%2.'# $%+# '3)665'&L")6-# +V/&7)6+"$5(&,(/&$# 320+6? B9'+,7+#$%)$#$%+#2"61#0&@@+,+"(+#9+$.++"#$%&'#(&,(/&$#)"0#$%+#'&3*6&@&+0#7+,'&2"#'$/0&+0#&" C+($&2"#W?W?e#&'#$%+#&"(6/'&2"#2@#$%+#9&)'#,+'&'$)"(+# > ) -#.%&(%#/"@2,$/")$+61#()"#6&3&$#$%+ &"(,+)'+#&"# > &" #0/+#$2# > 4 - #'&"(+ > &" d > ) || [ ( β e K ) ( ( 4 e > 4 ) ]
TX?\V
=%+#)")61'&'#2@#$%+#(&,(/&$'#&"#D&L?#W?WW#&'#'$,)&L%$@2,.),0#)"0#&'#&66/'$,)$+0#&"#$%+#@&L/,+?#=%+ @2,3/6)'#L&7+"#&"#=)96+#W?e#()"#9+#)0)*$+0#$2#)**61#$2#$%+#(&,(/&$#%+,+#91#,+*6)(&"L#$%+#@2,5 3/6)#@2,# > &" #.&$%#$%)$#&"#EV?#:W?KKN>-#,+*6)(&"L# > '&L #91# >′'&L d > '&L || > ) - #)"0#3/6$&*61&"L#$%+ +T*,+''&2"# @2,# Q v # 91# $%+# @)($2,# > ) ⁄ ( > ) e > '&L ) ?# B"(+# )L)&"-# .+# 02# "2$# ,+(233+"0# $%&' )**,2)(%#2@#*6/LL&"L#&"$2#@2,3/6)'H#,)$%+,-#'&"(+#+)(%#(&,(/&$#$%+#,+)0+,#.&66#+"(2/"$+,#.&66 9+#0&@@+,+"$-#&$#&'#3/(%#32,+#/'+@/6#$2#.2,U#2"+k'#.)1#$%,2/L%#$%+#(&,(/&$#/'&"L#$%+#)")61'&' 3+$%20'#'$/0&+0#)'#)#L/&0+?
EXERCISE 6.53# F2"'&0+,#$%+#+3&$$+,50+L+"+,)$+0#FE#(&,(/&$#2@#D&L?#W?WW#.%+"#9&)'+0#)'#&"#ET+,(&'+#W?GK?#!"#*),5 $&(/6),-#,+@+,#$2#D&L?#EW?GK#@2,#$%+#9&)'#(/,,+"$'#)"0#@2,#$%+#7)6/+'#2@#$%+#+6+3+"$'#2@#$%+#;<=#320+6 )$#$%+#9&)'#*2&"$?#[+$#$%+#)3*6&@&+,#9+#@+0#@,23#)#'2/,(+#%)7&"L#>'&L#=#G#UΩ-#)"0#6+$#>X#=#G#UΩ?#D&"0 $%+#7)6/+#2@#>4#$%)$#,+'/6$'#&"#>&"#+V/)6#$2#@2/,#$&3+'#$%+#'2/,(+#,+'&'$)"(+#>'&L?#D2,#$%&'#7)6/+#2@#>4@&"0#/v%-#>2-#/v -#)"08Qv ?#!@#vπ#&'#$2#9+#6&3&$+0#$2#G#3]-#.%)$#&'#$%+#3)T&3/3#7)6/+#v'&L#()"#%)7+#.&$% )"0#.&$%2/$#>4#&"(6/0+0_#D&"0#$%+#(2,,+'*2"0&"L#v%? Ans. PP^,Ω`,]\P,_o_`,E,GΩ`,]?P<\,_o_`,]D
457
458 Chapter 6 Bipolar Junction Transistors (BJTs) VCC (0 V)
RC
CC2
vo CC1
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6.8 Discrete-Circuit BJT Amplifiers
6.8.4 The Common-Base (CB) Amplifier L(;3#$,X$#25, 4$, "*.$, /2))$/&$-, &"$, 9*0$, -(#$/&+:, &2 ;#23)-5, &"30, $+('()*&();, #$0(0&2#, >), *+&2;$&"$#<, 6237+();, /*7*/(&2#0, --?, *)-8 --P, 7$#12#' 0('(+*#,13)/&(2)0,&2,&"20$,(),&"$,6M,/(#/3(&< !"$,0'*++%0(;)*+5,$S3(.*+$)&%/(#/3(&,'2-$+,21,&"$,*'7+(1($#,(0,0"24),(),L(;<,X $-,(),-$&*(+,(),K$/&(2),X $-,(),&"$,6B,$):,(),!*9+$ X<85,*77+:,-(#$/&+:,"$#$< VCC (0 V)
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Figure 6.67 ;'<#I#(2332"59)'+#)3*6&@&+,#/'&"L#$%+ '$,/($/,+#2@#D&L?#W?We?#;&<#EV/&7)6+"$#(&,(/&$#29$)&"+0#91 ,+*6)(&"L#$%+#$,)"'&'$2,#.&$%#&$'#=#320+6?
459
460 Chapter 6 Bipolar Junction Transistors (BJTs)
EXERCISE 6.54 F2"'&0+,#$%+#F;# )3*6&@&+,# 2@#D&L?#W?WW:)>#.%+"#0+'&L"+0#/'&"L#$%+#;<=#)"0#(23*2"+"$#7)6/+' '*+(&@&+0#&"#ET+,(&'+#W?GK?#C*+(&@&()661-#,+@+,#$2#D&L?#EW?GK#@2,#$%+#9&)'#V/)"$&$&+'#)"0#$%+#7)6/+'#2@ $%+#(23*2"+"$'#2@#$%+#;<=#'3)665'&L")6#320+6?#[+$#>'&L#=#>X#=#G#UΩ?#D&"0#$%+#7)6/+'#2@#>&"-#/v%-#>%/v -# v $ ⁄ v '&L - #)"0#Qv?#=2#.%)$#7)6/+#'%2/60#>'&L#9+#,+0/(+0#:/'/)661#"2$#*2''&96+#$2#02j>#$2#29$)&"#)" 27+,)66#726$)L+#L)&"#+V/)6#$2#$%)$#@2/"0#@2,#$%+#FE#)3*6&@&+,#&"#ET+,(&'+#W?GM-#$%)$#&'-#QNa#]Z]_ Ans. P^,Ω`,+\PO,_o_`,E,GΩ`,+?P\,_o_`,O
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6.8 Discrete-Circuit BJT Amplifiers
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461
462 Chapter 6 Bipolar Junction Transistors (BJTs) Vo Vsig (dB)
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464 Chapter 6 Bipolar Junction Transistors (BJTs)
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CHAPTER 6
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CHAPTER 6
PROBLEMS
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PROBLEMS
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CHAPTER 6
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PROBLEMS
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CHAPTER 6
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PROBLEMS
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PROBLEMS
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