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Differential Pair -Allegro Constraint managment

Prapz

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

  • Mashak

     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.

  • Prapz

    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.

     

     

  • Khurana

    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.

  • Prapz

    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..

     

     

  • Khurana

    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.

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