# PSPICE simulation of CMOS astable multivibrator

#### stn0091

Joined Jan 11, 2013
3

I want to simulate the above in OrCAD PSPICE. Here's my netlist:

Rich (BB code):
* 8.20

Vdd 1 0 5V

MP1 3 2 1 1 PMOD
MN1 3 2 0 0 NMOD

MP2 4 3 1 1 PMOD
MN2 4 3 0 0 NMOD

R1 3 2 1000
C1 2 4 1uF

.MODEL NMOD NMOS (VTO=2)
.MODEL PMOD PMOS (VTO=-2.0)

.ic v(2)=5

.tran 0.5us 10ms 0 1u uic

.PROBE
.END
Resistor and capacitor values were chosen for some arbitrary time constant. I just wanted to see the waveforms at Va, Vo and Vi.

V(2) corresponds to the gates of the first CMOS and I set that to 5V to "start" the circuit. However, I'm not seeing any oscillations when I simulate the circuit.

Where did I go wrong?

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