FET Small Signal Analysis
ENGI 242
ELEC 222
March 2003 FET Small Signal Bias 2
gm at Q
March 2003 FET Small Signal Bias 3
gm varies with VGS
GSm m0
P
DSSm0
P
V g = g 1 -
V
2I g =
V
March 2003 FET Small Signal Bias 4
FET Small-signal Equivalent Circuit
March 2003 FET Small Signal Bias 5
FET small-signal equivalent circuit that accounts for the dependence of iD on vDS.
FET Small-signal Equivalent Circuit
March 2003 FET Small Signal Bias 6
Determination of rd
March 2003 FET Small Signal Bias 7
Determination of rd
March 2003 FET Small Signal Bias 8
Common-source Amplifier
March 2003 FET Small Signal Bias 9
Common-source Small-signal Equivalent Circuit
March 2003 FET Small Signal Bias 10
March 2003 FET Small Signal Bias 11
.
CS Amplifier Voltage Divider Bias
March 2003 FET Small Signal Bias 12
vo(t) and vin(t) versus time
March 2003 FET Small Signal Bias 13
Gain magnitude versus frequency
March 2003 FET Small Signal Bias 14
Source Follower
March 2003 FET Small Signal Bias 15
Source Follower Small-signal ac Equivalent
March 2003 FET Small Signal Bias 16
Source Follower Output Resistance
March 2003 FET Small Signal Bias 17
Common Gate Amplifier
March 2003 FET Small Signal Bias 18
CG AC Equivalent Circuit
