Hi all,

I just have a little problem doing the ac analysis of the opamp. It is a fully differential telescopic opamp with a switched-capacitor CMFB(common mode feedback) circuit.  At first, I simulate the opamp with a sort of ideal CMFB and got the gain and UGB I want. Then, I put in the SC CMFB and did a tran analysis to see how many clock cycles the output CM needed to settle. After finishing both steps, I was trying to see how much gain and UGB I got with this SC CMFB. But here is the thing, how could I do the AC analysis with the output CM needs to settle in some clock cycles? Is there anyone having done this before could give me some advice? thanks in advance.

Mike