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 Differential pair width in allegro PCB editor 

Last post Fri, Sep 26 2008 11:05 AM by Javinder. 3 replies.
Started by rinj 25 Sep 2008 08:32 PM. Topic has 3 replies and 2978 views
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  • Thu, Sep 25 2008 8:32 PM

    • rinj
    • Top 500 Contributor
    • Joined on Thu, Sep 18 2008
    • Blr, Karnataka
    • Posts 23
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    Differential pair width in allegro PCB editor Reply

    Tool: Allegro PCB Performance option L Ver16.1

    Dear all,

    eg:I set net width for a differential net +X to 15mil, and maintain width for net -X as 8 mil in the constraint manager. But while routing the  -X net's with is automatically changing to 15 mil, same as +X and the change is not showing in the constraint manager.

    Is it bcz the tool is automatically default set to maintain same with for diff nets?

    thanks

    rinj

    • Post Points: 20
  • Thu, Sep 25 2008 9:51 PM

    • redwire
    • Top 10 Contributor
    • Joined on Wed, Jul 16 2008
    • Allen, TX
    • Posts 878
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    Re: Differential pair width in allegro PCB editor Reply

     Yes, the diff pair engine expects like widths.

    I am very curious to know why you want to do line widths like this for diff pairs?

    You can remove the diff pair prop and instead route as a matched pair and then it doesn't care about width.

    • Post Points: 20
  • Thu, Sep 25 2008 10:12 PM

    • rinj
    • Top 500 Contributor
    • Joined on Thu, Sep 18 2008
    • Blr, Karnataka
    • Posts 23
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    Re: Differential pair width in allegro PCB editor Reply

    Thank you redwire, for your comments for both of my posts. I was trying to help my colleague.

    we were just trying "width changes". Then we noticed that particular property, that's all.

    rinj

    • Post Points: 20
  • Fri, Sep 26 2008 11:05 AM

    • Javinder
    • Top 200 Contributor
    • Joined on Tue, Aug 12 2008
    • Goeteborg, 00-SE
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    Re: Differential pair width in allegro PCB editor Reply

     Idon't know if you have solved this. but one way to solve this,is to set MAX LINE WIDTH on each net and then route it as a group. Then it behaves like a diff pair. You can change the isolation by right click.

    Johan Javinder SAAB AB Electronic Defence Systems
    • Post Points: 5
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Started by rinj at 25 Sep 2008 08:32 PM. Topic has 3 replies.