How to do ac simulation in cadence for an opamp?

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i am also looking for this solution~~~
i am very upset that i can get opa's low-pass gain plot without those large cap and RES , without feedback, just deliver vn vp (vcm=2v,vdm=1v),
but once i put my design into the topology above, the result is not right at all~~~
 


It's a quite logical procedure (without large cap + res):
As the problem is connected with saturation due to offset, first you have to compensate this offset voltage. Then, run an ac analysis.

POCEDURE:
* Connect all dc supply voltages and run a dc analysis (Vdc at the non-inv. input, inv. input grounded).
* Determine the dc voltage Voff for which the output is in the middle of the linear portion of the transfer curve (for split supply: output=0 V). This is the offset voltage Voff.
* Apply this voltage Voff in series with the ac input (non-inv. terminal) and run the ac analysis (log scale!!)
* As a result, you get the open-loop gain vs. frequency (Bode plot)
_______-
Further question?
Regards
 
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