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 XO simulation using HB/PSS method. Linear IC Fail 

Last post Fri, Mar 29 2013 7:57 AM by ChrisMc. 2 replies.
Started by ChrisMc 29 Mar 2013 03:41 AM. Topic has 2 replies and 585 views
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  • Fri, Mar 29 2013 3:41 AM

    • ChrisMc
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    • Joined on Fri, Mar 29 2013
    • Posts 2
    • Points 25
    XO simulation using HB/PSS method. Linear IC Fail Reply

    Hi everyone,

    I hope that some of you give me a solution to fix my issue.

    I simulate my XO (32MHz, pierce topology) in HB, using the application note:

    http://www.cadence.com/Community/blogs/rf/archive/2012/12/19/new-mmsim-12-1-harmonic-balance-features-auto-tstab-and-auto-harmonics.aspx?postID=1315074

    My issue is that sometime,(with the same Test bench and same artiste stat and settings) the linear IC fail to find out the initial frequency.
    The result is that the final frequency is right but the magnitude is wrong. I'd compare with transient simulation (much longer), and when the IC linear works, the magnitude is right.

    the rror message is the following:
    "INFO: Can't find linear initial value. Using twotier Newton"

    I'm using cds6:

    IC: 615ISR15

    SW: v09

    MMSI: 111

    I've the same trouble for jitter simulation with PSS. And my jitter is pretty bad because the SNR is low.

    How can I do to remove the issue everytime ? because I don't know the reason.

    Thanks in advance for your help.
    Chris

     

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    • Post Points: 20
  • Fri, Mar 29 2013 7:47 AM

    Re: XO simulation using HB/PSS method. Linear IC Fail Reply

    Hi Chris,

    Well, the blog was about MMSIM12.1 and you're using MMSIM11.1 (so an older version), although that may not be the issue - it's hard to tell without seeing either your analysis setup (the bottom part of the input.scs file) or your spectre output log. Can you post both? (ideally give it a try using MMSIM12.1 using the auto modes that Tawna describes in her blog too).

    I don't know what "SW: v09" is, either, by the way.

    Regards,

    Andrew.

    • Post Points: 20
  • Fri, Mar 29 2013 7:57 AM

    • ChrisMc
    • Not Ranked
    • Joined on Fri, Mar 29 2013
    • Posts 2
    • Points 25
    Re: XO simulation using HB/PSS method. Linear IC Fail Reply

     Hi Andrew,

    Yes i know that my version is older than this used in application note the field are the same.
    The support has fix my issue. It seems that my error came from the initial condition which I set for the simulation. I'v removed it and know It works well.

    • Post Points: 5
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Started by ChrisMc at 29 Mar 2013 03:41 AM. Topic has 2 replies.