How to determine the dc PSR of bandgap

[tdy]

my op-amp in my band-gap is 100db dc

 

[PaloAlto]

You just have to do an ac analysis including the ac source in the supplies and check the gain to the output of the bandgap. The DC gain is the low freq part of it

BTW. Your opamp is 100dB??? That sounds huge, is it stable?

 

[tdy]

I use L=10 and cascode to push the open loop gain worst corner to 65dB of band gap to resist VDD and corner variation. It is strange that my simulation shows at tt corner the PSR is -100dB, is that reasonable? it seems my opamp has a 120 db gain, but when i do the open loop AC simulation of my bandgap, the op-amp gain is only 100db

Added after 1 hours 57 minutes:

it seems from op-amp output to input there is 20dB damp of noise besides the gain of the op-amp

 

[Tianbian365]

my op-amp in my band-gap is 100db dc

hi, the opa of your bg may get 100db by increase output risistance. i care the stable loop. Can you give me the result about positive & negtive bode sweep?

 

[tdy]

I do not quite understand Bode sweep, but you are right, I increase the output resistance, and compensation at op-amp output node. and when I do the open loop ac simulation, The loop is broken from the op-amp output use big inductor and I input ac source with big cap, by the way, how to bias cascode stage? is useing resistance for vdsat a good way ?

 

[tdy]

but it seems when i use res to bias cascode my system speed is limitted.