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 Differential Pair -Allegro Constraint managment 

Last post Wed, Nov 3 2010 10:23 PM by Prapz. 6 replies.
Started by Prapz 31 Oct 2010 12:05 AM. Topic has 6 replies and 4720 views
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  • Sun, Oct 31 2010 12:05 AM

    • Prapz
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    Differential Pair -Allegro Constraint managment Reply

    Hi ,

    I am new to allegro tool ...


    I have a GB Ethernet connector to which I have to connect 4 pairs of differential pairs .Now I want to match the length of all the differential pairs (and individual nets) to same length .how do I set the constraint and Also how do I apply the trace tuning.

    Thanks for the help in advance
    Prapz

    Am using 16.3 version

    • Post Points: 20
  • Tue, Nov 2 2010 2:21 AM

    • Mashak
    • Top 500 Contributor
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    • Hyderabad, Andhra Pradesh
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    Re: Differential Pair -Allegro Constraint managment Reply

     The best way to do this will be in Constraint manager. Just open the constraint Manager in Allegro and browse thru the tool.

    Also constraint manager Help will be useful for better understanding.

    • Post Points: 20
  • Tue, Nov 2 2010 2:40 AM

    • Prapz
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    Re: Differential Pair -Allegro Constraint managment Reply

    Hi,

    Thanks for the reply.Well I am new to allegro and finding it dfficult to understand the constraint manager flow.I have set the 4 pairs as differential pairs ,but my issue is to match the length for all the 4 pairs.

     

     

    • Post Points: 20
  • Tue, Nov 2 2010 1:02 PM

    • Khurana
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    Re: Differential Pair -Allegro Constraint managment Reply

    You need to create a match group that consists of all the differential pair nets.  This is done in Relative Propagation Delay tab and then specify the different values - there should be a video on Sourcelink that shows how this is done.

    • Post Points: 20
  • Wed, Nov 3 2010 1:02 AM

    • Prapz
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    Re: Differential Pair -Allegro Constraint managment Reply

    Thanks for the help.

    In ECSet the relative propagation delay tab there are matched groups for which the delay is set for the longest pin pair in pin pair tab for some matched groups.but i cant set it for diff pairs.

    Did you mean to group all the diff pairs ( Diffpair 1,Diffpair 2,Diffpair 3...) into matched group (in ECset) and then set the delay in Relative Propagation Delay tab?

    I am not able to create a match group (in ECset /nets) by selecting  all the diff pairs.

     What is Sourcelink.If you dont mind can u send me the link of the video.?

    Thanks in advance..

     

     

    • Post Points: 20
  • Wed, Nov 3 2010 9:25 AM

    • Khurana
    • Top 25 Contributor
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    Re: Differential Pair -Allegro Constraint managment Reply

    Yes, select the nets that make up the differential pair(s) to create a match group - match group rule always resolves down to the pin pair level.

    • Post Points: 20
  • Wed, Nov 3 2010 10:23 PM

    • Prapz
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    • Posts 11
    • Points 250
    Re: Differential Pair -Allegro Constraint managment Reply

     Thank you for the help

    • Post Points: 5
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Started by Prapz at 31 Oct 2010 12:05 AM. Topic has 6 replies.