How to simulate fully differential ota with sc cmfb

[newtoanalogdesign]

Hi,
I want to do ac analysis of fully differentila ota having sc cmfb circuit. i know the procedure of doing pss analysis first and then pac.. But i don't have spectre RF licence, so can any one explain how to simulate it using spctre simulator.....

What i did was transient analysis of circuit to find the stable Vcmfb value and then usnig a ideal voltage source i fixed that value, now simulated ac analysis. I want to know is there any other method than this one????

 

[watersky]

I simulate cmfb with stb analysis of spectre. Add iprobe of analogLib, which aim is connection when dc analysis, is not connection when ac analysis

 

[JoannesPaulus]

you can make an ideal cmfb using one vcvs and two resistors.

 

[newtoanalogdesign]

hi JoannesPaulus,

Can u explain in some more detail. How to connect it and if possible can u show the setup.

 

[Usman Hai]

you can run trasient analysis until your CMFB is settled. Now run AC analysis and in its option menu click yes "prevoppt". It should do the trick for you.