Diff Pairs

[peter408]

OKay, for the life of me I cannot remember how to set up differential pairs (getting old). I need to have different width/gap on different layers for each pair. I set up a constraint with the top layer width 12 and gap 5, then in the same constraint a width of 5 and gap of 7 on a different layer. Then I set the property to use that constraint. Not working too well. Am I supposed to assign the differential pair as well?

Peter

[may]

Originally posted by peter408
OKay, for the life of me I cannot remember how to set up differential pairs (getting old). I need to have different width/gap on different layers for each pair. I set up a constraint with the top layer width 12 and gap 5, then in the same constraint a width of 5 and gap of 7 on a different layer. Then I set the property to use that constraint. Not working too well. Am I supposed to assign the differential pair as well?

Peter

DIFFERENTIAL PAIRS CAN ROUTE WITH DIFFERENT WIDES/PITCH IN DIFFERENT LAYERS.

ATTENTION:
IN 41.2 AND 15.2,IT WORKS WELL, BUT NOT IN 15.0AND 15.1

[Skip Yutkus]

If You are using 15.2, then turn off diff-pair drc and play with the widths and gaps to get what you want by verifying on the cross-section spreadsheet, (new version in preferences), or using the calculator in electrical constraints.

Don't forget to set your plane layers as shields.

Skip

[madhusudhangk]

hi,

you can set automatically changing the width for perticular layers,using constraints.you should set the property for those signals net spacing type

Madhusudhan Kulkarni

Madhusudhan@sierra-etech.com

[mashak]

Hello everybody,


For setting different width on different layers for differential pairs is very simple in allegro, You need to just set the constraints in the "net physical type" & "net spacing type" and it provides a option for different layers .If you set there then whenever you change the layer the software takes care of the change in widths and spacing accordingly.

This is the right way to do this.