Is AC analysis for a bandgap reference required

[Chethan]

Hi all
Is AC analysis for a brokaw's cell BGR required. I have done the AC Analysis for the opamp used in the BGR and it is stable. So is it still necessary for me to do AC Analysis for my entire BGR also. If it is required, then can someone tell me how to do the setup for AC analysis.

Thanx in advance

 

[flushrat]

Break the loop, add a ac source at one node, then moniter the other node to see if the phase marigin is enough.

 

[huojinsi]

Inject a ac source in the feedback loop, then do ac analysis! Plot the difference of signal source two terminal, check the PM is enough or not !

 

[kumi]

Did you mean that we should do AC analysis for the opa for the load of the opa is changed?

 

[xwcwc1234]

Can someone provide a Spice nelist file for explanation ?

 

[bsrivastava]

I think that time domain (transient response) analysis should be enough for stability, bacause we know that the bandgap sees both negative and positive feedback but the amount of negative feedback is always greater than amount of positive feedback. This should confirm stability.

-Bharat

 

[dasong]

simulation the PSRR need the AC analysis,if use the OPA in bandgap reference ,the GB is also very important.