lecture10(20-3-11)
TRANSCRIPT
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7/27/2019 Lecture10(20-3-11)
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EE 332
DEVICES AND CIRCUITS II
Lecture 10
Small-Signal Models
and Single Transistor Amplifier (2)(CE Amplifier)
Ri
AMPLIFIER TYPES/TRANSCONDUCTANCE AMPLIFIER
Rs
vS
Ro
viGmRL
io
S ource Contr olcomponent Load
vi
v
m
o
AG
R=
TransconductanceAmplifier:toamplifyaninputvoltagesignalandprovideanoutputcurrentsignal
Foranidealtransconductancesince:
v m o
amplifier:Ri ,Ro A G R
and
Optimathe setting:Maximize
and
o
o m i
o L
i
i s
s i
i o
s i o L
i s o L
Ri G v
R R
Rv v
R R
R R
R R R R
R R R R
i
=+
=+
+ + >> >>
o
m
i
Gv
=
Ri
AMPLIFIER TYPES/CURRENT AMPLIFIER
iS
Ro
iiAiRL
i m iA G R
and
Currentamplifiers areoptimized byand
o
o i i
o L
s
i S
i s
o s
o i S
o L i s
i s o L
o
Ri A i
R R
Ri i
R R
R Ri A i
R R R R
R R R R
i
= +
= +
= + +
>
=
CurrentAmplifier:toamplifyaninputcurrentsignalandprovideanoutputcurrentsignal
Source Controlcomponent Load
i
i
Ai
Foranidealcurrent
ii
amplifier:Ri=0,Ro
io
Rs
AMPLIFIER TYPES/VOLTAGE AMPLIFIER
Optimathesetting:Maximize
and
i i
s s i
o L
i o L
o i L
s s i o L
i L
s i o L
i s o L
o
s
v R
v R R
v R
Av R R
v R RA
v R R R R
R R
R R R R
R R R R
vA
v
=
+
=
+
=
+ +
+ +
>>
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AMPLIFIER TYPES
/TRANSRESISTANCE AMPLIFIER
iS Ro
iiRm
RL
Source Controlcomponent Load
ii
Rs
m i o v i R A R A R =
TransresistanceAmplifier:toamplifyaninputcurrentsignalandprovideanoutputvoltagesignal
Foranidealtransresistanceamplifier:Ri=0,Ro=0
and
Currentamplifiersareoptimizedbyand
L
o m i
o L
s
i S
i s
i s o L
o
m
i
Rv R i
R R
Ri i
R R
R R R R
vR
i
= +
= +
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CE AMPLIFIER (INVERTING) WITHOUTBYPASS CAPACITOR/SMALL SIGNAL MODEL
Rs
vS
C1
R2
R1
RC
RE
Q1
C2
VCC
RL
vo
vo
vs RB RC RL
r rogmvbe
vbe
Rs
RE
CE AMPLIFIER (INVERTING) WITHOUTBYPASS CAPACITOR/OUTPUT RESISTANCE
vovs RB
RCr rogmvbe
vbe
Rs
RE
rc Ro
Rth vx
RE
r
Outputresistance:/ /CE
o c CR r R
th
b e
th
be b e e
th
Rv v
R r
rv v v v
R r
=+
= = +
Byvoltagedivision:rc
gmvbero
ic
ve
vb
CE AMPLIFIER (INVERTING) WITHOUTBYPASS CAPACITOR/OUTPUT RESISTANCE
vovs RB
RCr rogmvbe
vbe
Rs
RE
rc Ro
Rth vx
RE
r
Outputresistance:/ /CE
o c CR r R
Nodeequation
at
emitter:
1 1 1( )
1 1( )
e e x e
m be c
E th o
c m
e
o E th th o
c e
E th
v v v v g v i
R r R r
v g rv
r R r R r R r
an d
i vR r R
+ = + =+
= + + ++ +
= ++
rc
gmvbero
ic
ve
vb
CE AMPLIFIER (INVERTING) WITHOUTBYPASS CAPACITOR/INPUT RESISTANCE
vovs RB RC RL
r rogmvbe
vbe
Rs
RE
1 2/ / / /CE
i bR R R r
Inputresistance:
: ( 1)
( 1)
x x x E
xb E
x
K V L v i r i R
vr r R
i
= + +
= = + +
HigherresistancethanRE=0
rb
Ri
vx
Deadnetworkimpedance
Testsource
ix
rb
RE
ri
x
ie=(+1)ix
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CE AMPLIFIER (INVERTING) WITHOUT BYPASSCAPACITOR/OUTPUT RESISTANCE
vovs RB
RCr rogmvbe
vbe
Rs
RE
rc Ro
Rth vx
RE
r
Outputresistance:/ /
CE
o c CR r R
rc
gm
vbe
ro
ic
ve
vb
1
1 1 1
1 1
1 1[1 ] ( )
1 1
m
x E th th o
c o
x
E th
m
th
c o
E th
E th
g r
v R r R r R r r r
i
R r R
g r
r Rr r
R r R
R r R
+ + ++ += =
++
+ = + + +++
+
Taketheratio
CE AMPLIFIER (INVERTING) WITHOUTBYPASS CAPACITOR/GAIN
vovs RB RC RL
r ro
gmvbe
vbe
Rs
RE
ve
vovb ( 1)
, where
( 1)
1
o
m L EQ b E
LEQ L L C
CE o
v m L
b E
CE m L
v
m E
v rg R
v r R
R R R R
v rA g R
v r R
g RA
g R
=+ +
= + + +
Verylargeresistance1
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CE AMPLIFIER (INVERTING) WITHOUT
BYPASS CAPACITOR/SOURCE GAIN
vovs RB RC RL
r ro
gmvbe
vbe
Rs
RE
ve
vovb
Signalsourcevoltagegain:
Ri
/ / / /( ( 1) )
/ /
CE
i B b B E
CE
o c C
R R r R r R
R r R
= + +=
rcrb Ro
Gainwithsourceandload:
End of Lecture 10
CE AMPLIFIER (INVERTING) WITHOUTBYPASS CAPACITOR/CURRENT GAIN
vovs R
BRC
RL
r ro
gmvbe
vbe
Rs
RE
ve
vovb
Ri
/ / / /( ( 1) )
/ /
CE
i B b B E
CE
o c C
R R r R r R
R r R
= + +=
rcrb Ro
Terminalcurrentgain:
MaximizeAi whileRLo,ifRi=r Ai=gmr=
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