How to simulate switch-capacitor circuits-ac analysis

[jiawenyin]

I dont's know How to simulate switch-capacitor using ac analysis with spectre.
such as , fully differential opamp with switch-capacitor CMFB. Can you give me
some suggestions.
Thank you.

 

[Usman Hai]

There are few possible ways.
The easiest way is to run the transient analysis long enough for the CMFB to settle. It might take 4-5 clock cycles. Now perform AC analysis. In the AC analysis goto options and click "prevoppoint" to yes. This will start the AC analysis taking the operating point at the end of transient analysis.

 

[PaloAlto]

Don't forget to go to design->environment and write in the analysis order the ac analysis after tran: e.g. Analysis Order: dc tran ac