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Design >> Analog Design >> How to perform stability analysis
https://designers-guide.org/forum/YaBB.pl?num=1156429424

Message started by chviswanadh on Aug 24^th, 2006, 7:23am

Title: How to perform stability analysis
Post by chviswanadh on Aug 24^th, 2006, 7:23am

Hello,

I am designning a Switching regulator of continuous current mode constant off time topology. I am using spectre simulator for simulations. How can I perform STb analysis for this?

I tried the method of breaking the loop and inserting a probe but it is not giving the right results.

please help me with this

Title: Re: How to perform stability analysis
Post by Frank Wiedmann on Aug 24^th, 2006, 9:01am

Take a look at http://www.designers-guide.org/Forum/YaBB.pl?num=1133514560 and the links given there.

Title: Re: How to perform stability analysis
Post by fantusox on Sep 8^th, 2006, 8:16pm

Hi,
I am am doing the same project as you , I have difficulties in obtaining stability too. Did anyone manage to know how to break the stability? I have read the link but tried but fail.

Title: Re: How to perform stability analysis
Post by jbdavid on Sep 12^th, 2006, 11:51pm

are you looking at stability during ON time or OFF time?
or do you have a model linear model that considers both?
Jonathan

Title: Re: How to perform stability analysis
Post by chviswanadh on Sep 13^th, 2006, 12:30am

I need to find the stability for both on time and off time.

Title: Re: How to perform stability analysis
Post by fantusox on Sep 21^st, 2006, 6:51am

I need to find the stability of off time only. Some of the papers I read do not teach how to do the simulation of open loop response of the circuit .

Title: Re: How to perform stability analysis
Post by sheldon on Sep 21^st, 2006, 8:14am

Chviswanadh,

If you have access to SpectreRF, periodic stability analysis, pstab, was added in MMSIM61.
It performs stability analysis on circuits with periodic operating points. I have used it on similar
circuits and the results seem reasonable. That is the predicted phase margin seems to track the
phase margin predicted by the pulse response. BTW, you could also use periodic ac analysis and
back out the stability from the open loop gain and phase.

Best Regards,

Sheldon