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diff pair settings for different layers

PhilH

I need different settings for my diffpairs on different layers. I have seen it done many years ago but can't remember how it was setup.

What I need is for my diffpairs to change width/spacing when I jump to a different layer while routing.

I have layer sets turned on in the Analysis>Electrical modes but do not see where to enter the values for individual layers.

Thanks

Phil

  • riklee

    You use the Physical Constraint set in CM to add the line widths and DP settings for layer based diff pairs

  • PhilH
    So you can't set a unique line width for the diffpair on individual layers, other than the default line width for that layer?
  • riklee
    If you have differential pair sets that need other values you would need to control them with a different PCS e.g.:

    PCSet DIFFPAIR_5_10 = 5 outer and 10 inner
    PCSet DIFFPAIR_5_8 = 5 outer and 8 inner
    .
    .
    PCSet DIFFPAIR_12_6 = 12 outer and 6 inner

    Then in the Net/All Layers section assign the PCSet you need to the pairs.
  • PhilH
    I don't think that is what I'm wanting to do. Those diffpair sets would route the same width/spacing no matter what layer you are routing on.
    I need any given diffpair to route with one set of rules on one layer (3/5 internal), and if I jump to the top layer, with same diffpair, I need it to route with different width/spacing (7/10 external).
  • fxffxf

    Login to Cadence customer (https://support.cadence.com support and search:

    How to set up Diff Pairs to route different line/neck widths on different layers

    This may help you.

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