how to simulate the AC performance of the bandgap circuit

[qlk]

i want to simulate the AC performance ( DC gain ,phase margin or gain margin) of the bandgap circuit. Who can tell me how to add the AC voltage source in the BG circuit? The circuit is as in the picture.
thanks in advance

 

[tyanata]

Re: how to simulate the AC performance of the bandgap circui

Why do you want to simulate AC performance of the bandgap?

I think that AC analysis is needed only for simultaneus noise analysis!

 

[nxing]

For Bandgap, the input is VDD, so you just set the AC value to 1 and do the AC analysis.

 

[Btrend]

Re: how to simulate the AC performance of the bandgap circui

break loops at the input terminal + and - of OP, and insert 10G resistor series with 10F capacitors to GND before + and -, and AC noise at either one node, then check the node at the return path.
this is a reference
https://www.spectrum-soft.com/news/winter2001/loopgain.shtm