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 QRC runs for RC and C only av_extracted views report different values of net capacitance for a net 

Last post Wed, Oct 30 2013 10:09 AM by Meny Lea. 3 replies.
Started by bnugent 04 Apr 2013 09:31 AM. Topic has 3 replies and 2156 views
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  • Thu, Apr 4 2013 9:31 AM

    • bnugent
    • Top 500 Contributor
    • Joined on Thu, Jun 9 2011
    • Cambridge, MA
    • Posts 20
    • Points 280
    QRC runs for RC and C only av_extracted views report different values of net capacitance for a net Reply
    Hello all,

    To start things off I am using:

    IC6.1.4

    Assura 4.12.017

    QRC 9.14.002

    I’m trying to minimize parasitics in a circuit and I’ve encountered something weird.

    Upon completing a clean LVS, I run QRC and create two av_extracted views, one with “RC” Extraction Type and the other with “C Only” Extraction Type. I call them av_extracted_RCs and av_extracted_Cs accordingly.

    I'm trying to minimize parasitics in a circuit, and I’m using the Parasitics-> Report Parasitics ->Net Capacitors to view my progress.  I have encountered something weird when I look at the net capacitances. There is a difference in the total net capacitance whether I load av_extracted_RC or av_extracted_C! If I load my av_extracted_Cs it reports a total net capacitance X fF for a given net x, but if I load my av_extracted_RCs it reports more net capacitance (Y) fF for the same net x.

    Why does the extracted view with RCs show more net capacitance than the extracted view with only Cs? This is puzzling me and I hope someone has encountered this before. Thanks in advance.

    Cheers,

    Brian
    • Post Points: 20
  • Fri, Apr 5 2013 10:46 PM

    Re: QRC runs for RC and C only av_extracted views report different values of net capacitance for a net Reply

    Brian,

    Probably best to contact customer support over this so that we can investigate. I would expect them to be different (because the net is fractured into pieces when using RC), but I can't think (off the top of my head) why they should be significantly different.

    Regards,

    Andrew.

    • Post Points: 20
  • Thu, Apr 11 2013 2:01 PM

    • bnugent
    • Top 500 Contributor
    • Joined on Thu, Jun 9 2011
    • Cambridge, MA
    • Posts 20
    • Points 280
    Re: QRC runs for RC and C only av_extracted views report different values of net capacitance for a net Reply

    Andrew,

     

    I have contacted my local cadence support and resolved the issue.

     

     Cheers,

    Brian 

    • Post Points: 20
  • Wed, Oct 30 2013 10:09 AM

    • Meny Lea
    • Not Ranked
    • Joined on Sun, Sep 4 2011
    • Posts 12
    • Points 165
    Re: QRC runs for RC and C only av_extracted views report different values of net capacitance for a net Reply

    Hi,

     

    im having the same issue. what was the solution ?

    do you have CCR number ?

     

    thx

     

    meny 

    • Post Points: 5
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Started by bnugent at 04 Apr 2013 09:31 AM. Topic has 3 replies.