Using Differential Pairs in Allegro PCB Editor
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Resizing a Differential Pair
If a differential pair is already routed with specified gap, is there a way to change the
differential pair spacing?
Use the unsupported command Resize/Respace Diff Pairs to resize the differential
pairs. This command is available under Route > Unsupported Prototypes. This
command is useful when differential pair constraint changes are required after
differential pair routing is complete.
Gap changes are typically accomplished by maintaining the existing (imaginary) center-
line between coupled segments. When modifying any differential pairs, neighboring
elements are ignored, so DRCs are likely to appear after the command is run.
Constraints are not modified and will need to be changed to match the Resize/Respace
values applied.
Note: An important step is to run the Resize/Respace Diff Pairs command before (and
not after) changing the constraints. You should not run this command again on the
same differential pairs until after having updated the constraints to match the applied
Resize/Respace values. Else, the command will not recognize the modified differential
pair clines accurately.
