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Setting Diff Pair gap spacing vs. spacing to adjacent trace

RWest
I'm having trouble trying to set up diff pair spacing. The problem is I want to route diff pairs with 20 width, 22 pair gap, 110 space to adjacent traces. When I set the gap to 22 in the Physical Rule Set and the line-to-line to 110 in the Spacing Rule set, then I get a DRC for the GAP routing. When I set both of above to 22, the DRC is gone, but now adjacnt routing is allowed at 22. How can I set the gap to 22um and the default spacing to 110um? Thanks!
  • redwire

    Hopefully this post will clear it up.  Lots of posts in here with the same question.

     

    http://www.cadence.com/community/forums/T/13203.aspx

  • RWest

     

    Thanks, I following the procedure, but I'm using version 15.7.

    I've also tried assigning an eletrical Cset on the diff pair, still not able to account for both the gap and the adjacent space at the same time. I've spent alot of time trying every combo of settings, still not finding a solution. It can't be this hard can it?

  • mcatramb91

    Hello,

    Sounds like you are doing things correctly but you may of missed a step, let me summarize:

    1. Define your Diff Pairs using Logic > Assign Differential Pairs or inside of Constraint Manager.
    2. Define the trace width and diff pair gap in the Physical Rule Set (Preferred method is to define these in Constraint Manager but if you have different trace widths and diff pair gaps per layer you are forced to use the Physical Rule Set - 15.7 limitation)
    3. Add Net_Spacing_Type property to all of your Diff Pairs.
    4. Create a Spacing Rule Set for the clearance between the adjacent traces.
    5. Modify the Spacing Assignment Table to reference the Spacing Rule set created above when any other Net Spacing Type properties, including NO_TYPE, comes in contact with your diff pairs Net Spacing Type group.
    6. In Constraints Manager specify the Min Line Spacing for all your defined Diff Pairs the same or below your diff pair gap of 22.

    This should work and I think you must of missed a step above which is causing you to have mixed results.

    Hope this helps,
    Mike Catrambone

  • redwire

    RWest said:

    It can't be this hard can it?

     

    Nope.  It's not.  Search the forums.  The previous link I sent applies to your version as well.  The answer is clearly stated in this link.

    http://www.cadence.com/Community/forums/p/11141/13253.aspx#13253

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