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Got Stuck in Harmonic Balance Analysis

MarcoL

Hi all,

       Recently I needed to run a lot of hb analyses but always got stuck in the processing.  

      Not saying hb would not work, but it generally takes much more time than I expected. So I looked into the output log while monitoring the CPU utilization of spectre. Here is the problem I found.

     DC and AC analyses were run before HB, and both seemed to work well with a CPU utilization of around 400%. So I thought computing resources were abundant and thus expected HB analysis to utilize more computing resources to move faster. However, it turned out HB got stuck between "Important HB parameters" and "initial residual" for plenty of hours, while the CPU utilization fell down to 100% or less. It's like:

   Important HB parameters:

   RelTol = 1.00e-3

   abstol(I) = 1.00e-12 A

  abstol(V) = 1.00e-6 V

  residualtol =1.00e+00

  lteration = 3.50e+00

  steadyration =1.00e+00

 maxperiods =100

( Here spectre got stuck for plenty of hours, not even bother to move! )

**initial residue**

     I am not sure whether or not it's common; Worse, no idea attained after I consulted the local Cadence AE. She checked my settings and said there was nothing wrong. "Maybe it has something to do with the host machine", she said.

  So does anyone know what spectre is doing where it gets stuck in my case? Any solutions?

  By the way, I am using IC6.1.6-64b.500.10 and spectre 15.1.0.345.isr2.

Thanks a lot!

Marco

2016.12.02

  • Andrew Beckett

    Hi Marco,

    I don't think there's really enough information to work on here. Please contact customer support so that we can follow this through formally - we need to see the log files, and may well need access to the testcase, and probably get an RF specialist looking at this. Without knowing far more about the circuit, I doubt I could answer this via the forums - the same would be true of other AEs who work in this space.

    Kind Regards,

    Andrew.

  • MarcoL
    Hi Andrew,

    Thanks for your reply.
    I guess that's all we can do here. As long as the analysis can finally disgorge some results, no matter how long it would take, we would choose to put up with it and then forget it. Involvement of different guys from two companies may be a much larger project than a single simulation.
    I posted out the issue just hoping to see whether or not you guys may have a clue, since you guys look sooooooo erudite, not really depending on a direct solution. You have done much more than I expected and sincerely thank you sir.
    Maybe sometime later I would somehow resolve the problem, in which case I would post it here.

    Regards,
    Marco.
  • Andrew Beckett

    Marco,

    Not necessarily - it may just be having a webex with an expert in this area can pinpoint a setup problem which is exacerbating the problem - it's very hard to know without seeing at least the log file and the analysis statements in the log file. It may not be a big project to figure this out...

    Regards,

    Andrew.

  • MarcoL
    Andrew,

    The thing is the company where I am working has stringent information security polices. Just imagine that even download of results files from the servers to the local need permission from your manager, and some guys are always watching you. So I seriously doubt they would permit me to do what you kindly proposed.

    Regards,
    Marco.

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