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Design >> Analog Design >> Remove the compensation cap, the opamp still stable?
https://designers-guide.org/forum/YaBB.pl?num=1467761832

Message started by ludake on Jul 5^th, 2016, 4:37pm

Title: Remove the compensation cap, the opamp still stable?
Post by ludake on Jul 5^th, 2016, 4:37pm

I built a regular 2-stage opamp with one compensation cap..... when i remove this cap, i see in the ac simulation that the phase margin is not enough, but in the transient simulation, i can't see the opamp is oscillating ?
what't happening???
[img][/img]

Title: Re: Remove the compensation cap, the opamp still stable?
Post by buddypoor on Jul 6^th, 2016, 12:52am

ludake wrote on Jul 5^th, 2016, 4:37pm:

Oscillation will occur in case of a closed feedback loop only. Did you apply feedback during TRAN simulations?

Title: Re: Remove the compensation cap, the opamp still stable?
Post by loose-electron on Jul 6^th, 2016, 7:55pm

That is not an Op-amp, that is an OTA.

That said buddy is right about the feedback