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Unable to plot phase noise

sebastion

Hi,

After running pnoise: jitter analysis, I wanted to plot the phase noise by choosing:

Direct Plot Form => pnoise jitter => Phase Noise => dBc => Plot

I got some error messages shown as follow:

*Error* flip: can't handle flip(nil)
*Error* flip: can't handle flip(nil)
*Error* flip: can't handle flip(nil)
*Error*   Evaluating expression (_drplPmNoise(?modifier "dBc" ?dsb
          t)).
*Error* ("abs" 0 t nil ("*Error* abs: can't handle abs(nil)"))
*Error*   Trying to plot expression <_drplPmNoise(?modifier "dBc"
          ?dsb t)>, which does not evaluate to an object that can be
          plotted, like waveform or parametric wave. Please refer to
          the Wavescan User Guide to see what all types of objects
          can be plotted in Wavescan. Expression which evaluates to
          only those type(s) of objects can be plotted.

I could get the plot when I choose:

 Direct Plot Form => pnoise => Phase Noise => Plot

May I know what is the problem?

 Thanks.

  •  What subversion of virtuoso or icms are you using?  This looks suspiciously like a known issue that was fixed about 18 months ago in IC 5.10.41.500.6.130 and 6.1.3.500.5 .   I recommend upgrading to the latest ISR available on downloads.cadence.com .  You may need to contact Cadence Customer Support if upgrading your software doesn't resolve your issue.

     Also, if you have your nets named Vout+ or Vout-, try renaming them to VoutPlus and VoutMinus.  There is similar issue where that was causing issues (and is fixed in the latest ISR on downloads.cadence.com).

     

    best regrds,

    Tawna

     

  • Hi Tawna,

    Was just about to reply to this when I saw your post. Looks like CCR 602731 which was fixed in 5.10.41.500.6.142 . I think there have been other related issues (so some similar problems were fixed in an earlier CCR which you found) - and there's some dependency on the simulator subversion too. The key though is in non-alphabetic/numeric characters in the output names as you pointed out though.

    Regards,

    Andrew.

  • Thanks for the quick reply, Tawna & Andrew.

    Tawna: I am currently using 5.10.41.500.6.138 and I did not use any + or - sign for the nets.

    My setup is shown as follow:

    simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=65.0 \
        tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
        digits=5 cols=80 pivrel=1e-3 sensfile="../psf/sens.output" \
        checklimitdest=psf
    pss  (  IVCOTOP.cko\<9\>  0  )  pss  fund=2e9  harms=20
    +    errpreset=conservative  tstab=15n  saveinit=no  annotate=status
    +    tstabenvlp=no
    jitter1  (  net23\<5\>  0  )  pnoise  sweeptype=relative
    +       relharmnum=1  start=100k  stop=10M  dec=10  maxsideband=7
    +       annotate=status
    jitter2  (  net23\<5\>  0  )  pnoise  sweeptype=relative
    +       relharmnum=1  start=-(100k)  stop=-(10M)  dec=10  maxsideband=7
    +       noisetype=correlations  cycles=[0  -2]  annotate=status
    modelParameter info what=models where=rawfile
    element info what=inst where=rawfile
    outputParameter info what=output where=rawfile
    designParamVals info what=parameters where=rawfile
    primitives info what=primitives where=rawfile
    subckts info what=subckts  where=rawfile
    saveOptions options save=allpub

    So is it something fixable by upgrading the ISR? Thanks.

  • I think the problem in this case is caused by any signal name which needs mapping. Bus signals (such as what you have here) are being mapped too. If I remember rightly, the problem was caused by the mapping not being applied properly in the results post-processing.

    So I believe the ISR should fix it.

    Best Regards,

    Andrew.

  •  Hi Andrew,

    We upgraded the subversion to 5.10.41.500.6.143 and we are able to plot the phase noise (from pnoise jitter option). Thanks.

    However, we ran into another problem. In this subversion, we could not run the simulation in GUI mode.The simulation can be carried out by running runSimulation in netlist directory.

    The error messages are shown as follow:

    *Error* Errors encountered during simulation. The simulator run log has not been generated.
    Possible cause could be an invalid command line option for the version of the simulator
    you are running. Choose Setup->Environment and verify that the command line options
    specified in the userCmdLineOption field are supported for the simulator.
    Alternatively, run the simulator standalone using the runSimulation file in the netlist
    directory to know the exact cause of the error.
     

    And the runSimulation file is shown as below:

    spectre  -env artist5.1.0 +escchars +log ../psf/spectre.out -format sst2 -raw ../psf   +lqtimeout 900 -maxw 5 -maxn 5 input.scs
     

    May I know what is the cause of the problem? Thanks.

  • My guess is that something in the UNIX environment as inherited by the shell that runSimulation is running is messing things up. You might want to try using:

    system("/path/to/runSimulation")

    in the CIW, and then looking in the terminal window that you launched icfb from to see if there are any messages appearing which give any clues?

    Otherwise go to http://support.cadence.com and log a service request. That's what customer support is for ;-)

    Regards,

    Andrew.

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