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Simulators >> Circuit Simulators >> using pnoise analysis. Slow.
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Message started by basem on Sep 11th, 2014, 7:44pm

Title: using pnoise analysis. Slow.
Post by basem on Sep 11th, 2014, 7:44pm
Hello,

I have a mixed-signal circuit. I use pss successfully (Cadence) and attain a periodic steady state.

The PSS run uses multiple threading and about 10GB+ of memory.

When the pnoise start (which is set for wide frequency range), the simulation time is at least one order of magnitude longer (in fact, after a very long wait, the sim is still running at 80% completion). I checked and found out that pnoise uses single processor to run the circuit whereas pss uses 8 of them and lots of memory.

I think I am using the latest of the old Cadence software (IC5141) and I think I am running mmsim with APS option in the ADE activated.

The sim is running the 64 bit binary.

I am puzzled on why Cadence settled with non-parallel processing for pnoise?! It is not always the case that we need period noise analysis at a narrow band of operation!!

I have to now compromise on what I want to measure in the simulator to have a reasonable overall simulation time when I need to run a large number of these sims across corners and mismatch.

Any ideas? experiences? feedback? is highly appreciated.

And I can't use some other tool. I am stuck with this tool for this circuit.

Thank you  :)

Basem

Title: Re: using pnoise analysis. Slow.
Post by sheldon on Oct 17th, 2014, 6:23am
Basem,

 How did you setup the PNOISE analysis? How many sidebands are
you using? The point of the question is that the pnoise algorithm
was updated significantly several years ago in the MMSIM release
stream. If you are just running the existing netlist with a more
recent release, then it is likely the issue is your analysis setup.
If have not tried it, use the pnoise full spectrum option. It should
accelerate the simulation time significantly.

                                                                  Sheldon

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