Using Differential Pairs in Allegro PCB Editor
February 9, 2012 4 Product Version 16.5
Primary Gap Specifies the ideal edge-to-edge spacing between a pair of
nets in the differential pair that should be maintained for the
entire length of the pair.
Primary Width
Specifies the minimum width of each line of the
differential pair.
Neck Gap
Specifies the edge-to-edge spacing between nets of a
differential pair as it goes through tight areas.
Neck Width
Specifies the minimum allowable width for a line in a
differential pair as it goes through tight areas.
Coupled Tolerance (+) Specifies the allowable positive deviation from the Primary
Gap for a differential pair to still be considered edge-
coupled.
Coupled Tolerance (-) Specifies the allowable negative deviation from the Primary
Gap for a differential pair to still be considered edge-
coupled.
Minimum Line Spacing A line-to-line check to make sure that the other settings are not
violated.
Creating a Differential Pair
This section covers the following two methods to create a differential pair.
▪ Creating Differential Pairs in Constraint Manager
▪ Auto Creation of Differential Pairs
Creating Differential Pairs in Constraint Manager
To create a differential pair in Constraint Manager, do the following:
1. Open the Net > Routing > Differential Pair worksheet.
2. Right-click on the Net/Xnet object.
3. Select Create > Differential Pair from the pop-up menu.
