How to fix the problem of ADS to simulate the power amplifier?

[hhhhh$$$$]

This is the power stage of the multistage power amplifier that I am working on. Since I want to design the neutralization structure, I need to find the capacitance of these two neutralizing capacitors. Below is the power stage of my design and the simulation parameters I use. Could you tell me how to find the capacitance of these two neutralizing capacitors? Also, why my stability factor is always -1? How can I fix the problems? Thanks a lot.

 

[BigBoss]

Why M2 is isolated in term of AC ? The Gate of M2 must be connected to GND in terms of AC. Disconnect DC Feed5 and connect the Gate of M2 to Vgs3 directly. DC Sources are short for AC..

 

[hhhhh$$$$]

Why M2 is isolated in term of AC ? The Gate of M2 must be connected to GND in terms of AC. Disconnect DC Feed5 and connect the Gate of M2 to Vgs3 directly. DC Sources are short for AC..

I change my circuit according to your suggestion, but I still can not get the stable circuit(K>1) and further get the capacitance of the two capacitors. Can you tell me what to do? Thank you.

 

[BigBoss]

First, check the DC Conditions.