Example 7.7: Frequency Response Of Small-Signal Model Of A FET Amplifier

** Circuit Description **
* input signal and source resistance
Vi 1 0 AC 1V
R 1 2 100k
* small-signal equivalent circuit
Rin 2 0 420k
Cgs 2 0 1pF
Cgd 2 3 1pF
Gds 3 0 2 0 4m
* load
Rl 3 0 3.33k
** Analysis Requests **
.AC DEC 10 1e3 1e11
** Output Requests **
.PLOT AC VdB(3) Vp(3)
.probe
.end
Application of the Miller Theorem

** Circuit Description **
* input signal and source resistance
Vi 1 0 AC 1V
R 1 2 100k
* small-signal equivalent circuit
Rin 2 0 420k
Cgs 2 0 1pF
Cgd_in 2 0 14.3pF
Eo 0 3 2 0 13.2 ; Vo=-gm*RL*Vgs
* load
Rload 3 0 1
** Analysis Requests **
.AC DEC 10 1e3 1e11
** Output Requests **
.PLOT AC VdB(3) Vp(3)
.probe
.end