How can I simulate a differential SC CMFB circuit?

[gsheng]

Someone here metioned how to simulate a differential OTA. But SC CMFB is ready in transition analysis. How can I simulate its AC characterstics?
Thanks.

 

[eda4you]

I would suggest you to stimulate a step-response. It's a fast and good verification. Look for "Characterizing Differential Amplifiers for Communications Circuits", a Cadence tutorial from David. This one is fantastic. I have uploaded it many times, therefore please search in the forums. Also look for the Kundert book (Designer's guide to Spice and Spectre).

 

[terryssw]

Normal AC analysis cannot simulate the differential opamp with SC-CMFB. Try the PSS and PAC analysis (also detailed in Kundert's papers) from Spectre. Or you must put other continuous-time or ideal CMFB if you using normal AC analysis.

 

[avinash]

how can we calculate gain and phase margin

 

[jiangwp]

I think the way of simulation for ac and tran should do the same time.
the simulation is like doing in the SC circuit.

The spectre RF can do the kind of simualtion. you can refer to the user guide of specture RF.

 

[beckchm]

but no detail info to refer to