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How do I access the real value of a resistor used in a transient simulation at a given PVT?

CADcasualty

I have a schematic that contains a "smart note" that evaluates a SKILL expression and displays the result on the schematic. The basis of this comes from Andrew Beckett's code that uses dynamic scoping to temporarily set ilInstPath which allows me to access information about instances via their cdsParams.

My schematic depicts a simple resistively loaded, differential amplifier whose gain is just gm*R and I want the smart note to display that gain after a transient sim completes. At the completion of the sim the skill code in the note interrogates the transistor and extracts it's gm (via transient operating point annotations) but I can't similarly extract the value of the resistor because TSMC annoyingly didn't provide transient operating point capability for resistors (or capacitors, but they did for transistors). The actual resistor value is a function of temperature and what process corner I'm in, but I don't know how to get the actual value so that I can calculate gm*R. I know R=V/I but the resistors don't appear to be enabled to provide transient current annotations either. Is there an alternative way access the value of a resistor used in a transient simulation?

  • Andrew Beckett
    in reply to CADcasualty

    With a bit of a recursive function and some pattern matching, it's not too bad - with this code:

    procedure(abCopyAndReplaceOpParamExprList(l1 @key pat (from "OP\\(") (to "OPT("))
  unless(pat
    pat=pcreCompile(from)
  )
  foreach(mapcar elem l1
    case(type(elem)
      (list abCopyAndReplaceOpParamExprList(elem ?pat pat ?to to))
      (string pcreReplace(pat elem to 0))
      (t elem)
    )
  )
)

    You can then do:

    userCdf->simInfo->spectre->optParamExprList=abCopyAndReplaceOpParamExprList(userCdf->simInfo->spectre->opParamExprList)

    I don't know whether there is indeed some case where OPT is needed over OP, but at least the above code should do the mapping for you.

    Regards,

    Andrew.

  • CADcasualty
    in reply to Andrew Beckett

    That code is just way beyond my pay grade...

    Speaking on behalf of this forum, you do know you're not allowed to ever retire, right? ;-)

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