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Design >> Analog Design >> Monte carlo analysis in spectre
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Message started by kayathi on Oct 18^th, 2004, 11:53pm

Title: Monte carlo analysis in spectre
Post by kayathi on Oct 18^th, 2004, 11:53pm

I have done wafer level characterization for transistor mismatches. I want to put these numbers into spectre for circuit evaluation purposes.The problem is I am having hard time figuring out how to use monte carlo analysis in spectre. I have gone through the document on this in designer's guide, but still the procedure for doing this is a little obscure. THe documentation in spectre's user guide isn't that helpful.

Can somebody tell me where i can find a better documentation or a tutorial of some sort.

Thanks
Kayathi

Title: Re: Monte carlo analysis in spectre
Post by ywguo on Oct 19^th, 2004, 5:53am

Hi,

If you know anything about monte carlo analysis with model parameter distribution using SPICE, please put light on me, too. I always wonder how to analyze the offset voltage accurately using SPICE. :)

Thanks
Yawei

Title: Re: Monte carlo analysis in spectre
Post by Andre on Nov 15^th, 2004, 4:34pm

This should be very straightforward. You might want to specify the output in the Analog Artist first (e.g. for a current mirror with a gain of 1 you can specify current_mismatch = Iout - Iin).
Then you open the MC tool and you should see your output right there. Specify the number of runs and the mismatch / process / both.
Then run the simulation.
The MC tools is only a wrapper around the artist simulation that you already specified. Spectre requires an initial run in Artist to get the mean values right. The deviation (process / mismatch) should be specified in the model files.
Run the simulation and look at the results (e.g. histogram for the current_mismatch).

Andre

Title: Re: Monte carlo analysis in spectre
Post by kayathi on Nov 16^th, 2004, 3:31pm

Thanks Andre
The problem I have is specifing the deviation in the model files.
If you have a sample deviation file that would be a lot helpful.
Thanks
Kayathi

Title: Re: Monte carlo analysis in spectre
Post by Andrew Beckett on Nov 21^st, 2004, 10:13pm

Did you read this:

http://www.designers.guide.com/Modeling/montecarlo.pdf

That would probably answer your questions.

Regards,

Andrew.