LVS with a schematic containing variables

Discussion in 'Cadence' started by Ck seok, Dec 1, 2003.

  1. Ck seok

    Ck seok Guest

    I created a symbol for a certain schematic(A) containing variables
    by using pPar("Wp") and so on.

    In testing schematic, I did parametric sweep for the variable, "Wp".
    And I got the proper Wp.

    Do I have to replace pPar("Wp") with the obtained value of Wp manually
    in the schematic(A) to do LVS?

    When I didn't replace it, I got error in LVS because pPar("Wp") was in the
    netlist of the schematic.

    I am using the cadence tool.

    Thank you in advance.
     
    Ck seok, Dec 1, 2003
    #1
  2. Ck seok

    S. Badel Guest

    hmmm,
    layouts cannot cantain variables, the dimensions are
    fixed.
    so, LVS will recognize there is a transistor but
    will issue an error when comparing the device
    parameters.
    You may accept the error, knowing that the
    transistor you drawn is of the right size but
    if you want a successful LVS run you must
    introduce a numerical value in the schematic.

    one trick may help : if you do another schematic
    in which you place a instance of your cell
    and give the parameters a numerical value,
    then LVS will not complain.
    then you can have for instance a generic
    inverter cell, with parameters (and no layout)
    and multiple inverter layouts like inv1 inv2...

    hope this helps.
    stephane
     
    S. Badel, Dec 1, 2003
    #2
  3. I suspect you're doing a parametric simulation first, and then when you do an
    LVS, it needs to know the default value for the parameter Wp. You would need to
    set the default value of the parameter Wp in the CDF for the cell which contains
    the reference pPar("Wp") - or it needs to be specified on the instance at the
    level above.

    There should be no need to change your pPar("Wp") references in the schematic
    design for you to do LVS, provided that you define Wp somewhere...

    Regards,

    Andrew.
     
    Andrew Beckett, Dec 1, 2003
    #3
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