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bison

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PSS on VCO and divider
Apr 06^th, 2005, 1:44pm

I'm doing a PSS+PNoise simulation on a VCO and divide-by-4. The VCO is at 4GHz, and I'm expecting 1GHz at the output of the divider. But PSS gives me a frequency of about 500MHz, which leads to a failure in converge. even tstab is set long enough. If I run the simulation individually for the two blocks, there's no problem. The error message is like:

Error found by spectre at time = 50.943 ns during periodic steady state analysis 'pss'.
After the dynamic adjustment of pstab, PSS still failed.

During all simulation, I set:
Number of harmonics = 10
method = gear2only
steadyratio = 1

Thank you very much for help!

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Andrew Beckett Senior Fellow Offline Life, don't talk to me about Life... Posts: 1742 Bracknell, UK	Re: PSS on VCO and divider Reply #1 - Apr 7^th, 2005, 1:03pm What version are you using? There have been a few fixes recently to improve the convergence and handling of autonomous PSS. So if you're using IC5033 or IC5141, and are not using a recent ISR, then I'd recommend that. Regards, Andrew.
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bison New Member Offline Posts: 2	Re: PSS on VCO and divider Reply #2 - Apr 11^th, 2005, 7:39am I'm using 5033... ???
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Andrew Beckett

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Life, don't talk to
me about Life...

Posts: 1742
Bracknell, UK

Re: PSS on VCO and divider
Reply #3 - Apr 11^th, 2005, 11:07pm

Is a recent subversion though? Help->About in the CIW should tell you the subversion and build date (I think), or you can do "icms -W" and "icms -V" from the UNIX prompt to tell you.

I assume you've ticked the oscillator option on the PSS form, and have set the nodes for the oscillator mode to be the output of the divider?

Have you tried setting liberal, moderate, or conservative
errpreset, and leaving everything else at default (hit the defaults button on the PSS options and the Simulator->Options->Analog form).

Regards,

Andrew.

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