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 Captab parameter plotting across voltage 

Last post Mon, Sep 3 2012 5:08 PM by Eshar. 2 replies.
Started by Eshar 31 Aug 2012 02:48 PM. Topic has 2 replies and 966 views
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  • Fri, Aug 31 2012 2:48 PM

    • Eshar
    • Not Ranked
    • Joined on Sat, May 12 2012
    • Posts 14
    • Points 205
    Captab parameter plotting across voltage Reply

    Hello,

    I am trying to generate a plot of one of the capacitance values generated by captab. My approach is as follows:

    1. Use stimulusFile to include the instruction: Cap_dcInfo info what=captab detail=nodetonode sort=name threshold=0 where=logfile

    2. Set up captab analysis: Analysis( 'dc ?captab t ?detail "nodetonode")

    3. Run parameteric analysis across voltage to generate multiple cap. tables:

    paramAnalysis( "vdd" ?start vstart ?stop vstop ?step vstep)

    paramRun()

     

    This seems to work when I only run step 2 and 3 meaning I see the multiple cap. tables in the spectre.out file. However, I am having trouble figuring out how to plot a specific capacitance value from the generated tables with the independent variable being "vdd". Although an example exists in a previous post http://www.cadence.com/Community/forums/p/21764/1309486.aspx, it does not include the stimulus used and it did not attempt to plot multiple values but rather only print a single value.

     

    Any help will be greatly appreciated. 

     

    • Post Points: 20
  • Mon, Sep 3 2012 9:50 AM

    Re: Captab parameter plotting across voltage Reply

    A better discussion would be to look at http://www.cadence.com/Community/forums/t/20426.aspx?PageIndex=2
    (although that's more to do with seeing it over time)

    You don't really need to use stimulusFile to turn on captab. Just do steps 2 and 3, and then if you do:

    selectResult('captab)
    outputs()

    you'll see all the available outputs. You can also access it from the results browser and then send to the calculator to find the right expression. For example:

    pv("out : net9" "Total" ?result 'captab)  ; don't need the ?result bit if you've used selectResult first

    The second arg for pv could be "Variable", "Fixed", or "Total". Because it was a parametric sweep, you'll see the capacitance value versus your swept variable.

    Andrew.

    • Post Points: 20
  • Mon, Sep 3 2012 5:08 PM

    • Eshar
    • Not Ranked
    • Joined on Sat, May 12 2012
    • Posts 14
    • Points 205
    Re: Captab parameter plotting across voltage Reply
    Thanks for the help. I didn't realize that 'captab was a result name. I thought that the circuit info had to be set in the stimulus file.
    • Post Points: 5
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Started by Eshar at 31 Aug 2012 02:48 PM. Topic has 2 replies.