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DC sweep using different sweep variables in corners

Mark McMorris

Hi,

I am trying to dc sweep different types of trim codes by putting them in corner runs.

For example I set "TRIM" as a DC design variable and use it in the dc analysis sweep variable name, with a range from VAR("STARTCODE) to VAR("ENDCODE"). I also have different types of trims: TRIM_A TRIM_B TRIMC.... and I set TRIM=TRIM_A, TRIM_B.... for different corners

This unfortunately did not work. I also tried to add parentheses ex. TRIM=(TRIM_A) based on a previous post but it still didn't work.

Please let me know if you have any suggestions.

  • ShawnLogan

    Dear Mark,

    Mark McMorris said:
    For example I set "TRIM" as a DC design variable and use it in the dc analysis sweep variable name, with a range from VAR("STARTCODE) to VAR("ENDCODE")

    I am not sure if more recent versions of the Cadence tools have changed, but from page 7 of the support article entitled "Virtuoso Analog Design EnvironmentXLVariables, Sweeps andCorners" at URL:

    support.cadence.com/.../ArticleAttachmentPortal

    it states: 

    "There are a few exceptionswhere  you don’t useVAR()

    –DC Sweep on a design variable

    –Frequency/tone settings in some  RFanalyses"

    Hence, unless things have changed since Virtuoso IC6.1.8 ISR5, your methodology may indeed not work as you desire. If I understand your objective correctly, you might consider running a corner analysis where you perform a DC operating point and vary design variable TRIM between STARTCODE and ENCODE in your corner setup. If your values of STARTCODE and ENCODE differ with the value of TRIM, you might consider making STARTCODE and ENCODE conditional expressions dependent on the value of TRIM.

    I do not have access to more recent Cadence tools and cannot verify that the VAR() behavior for DC sweeps of a design variable has changed (sorry!)- so you might consider checking with customer support.

    Shawn

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