I've modelled a simple charge-pump circuit in PSpice that uses some P-channel MOSFETs. I thought I had a handle on how P-channels worked, but PSpice is giving me results I don't understand. See the circuit attached. The two voltage sources at the bottom (V2 and V3) are essentially complimentary PWM. When one is high, the other is low, and vice versa.
When V2 is low, M1 turns on, and C1 is charged to 5V. During that time V3 is high, so M2 is off. Then, V2 goes high, which pushes C1 to 10V. V3 goes low, which turns M2 on, charging C3 up to 10V.
Next, V2 goes low and V3 goes high again. At this point, I thought M2 should go off again. But PSpice shows C3 rapidly losing charge. When I probed M2 with a current probe, there is a large negative current spike through it. So C3 is basically discharging itself through M2.
If V3 is high during that time, how is the transistor conducting current? Or is PSpice in error?
Thanks!