Using Differential Pairs in Allegro PCB Editor
Learn more at Cadence Support Portal - https://support.cadence.com
© 2019 Cadence Design Systems, Inc. All rights reserved worldwide. Page 27
Example of pinuse on a net that will NOT consider the entire net a differential pair:
Pin Type
U1.12 TRI
C1.1 OUT
R1.1 OUT
Example of pinuse on a net that WILL consider the entire net a differential pair:
Pin Type
U1.14 TRI
C3.1 IN
R3.1 IN
Issue 2: How to Remove Electrical Differential Pair Objects from
Constraint Manager
I have deleted all differential pair properties from all nets in my design, but some
differential pair objects still show up in Constraint Manager. A right-click action on the
differential pair in Constraint Manager displays a pop-up menu where I would usually
delete the differential pair, but the Delete command is grayed out. How do I delete
these differential pair objects?
Solution
These differential pairs may have been electrically (or automatically) defined by a
component's signal model. To remove these differential pairs, you must first determine
the signal model that defines the differential pair and remove the differential pair
definition from the signal model.
To find the SIGNAL_MODEL
1. Right-click on the differential pair. The differential pair is highlighted in Allegro
PCB Editor.
2. Choose Display > Element (Find Filter set to Comps only).
3. Select a pin of each component that is connected to the differential pair.
4. Look for the SIGNAL_MODEL property assigned to a component.
