What's Good About ASA Differential Pair Swapping? - The Secret's in the SPB16.2 Release!

5 Feb 2009 • 1 minute read

And the new features list just keeps going on and on - it's terrific!

In the SPB16.2 release, the Allegro System Architect (ASA), and System Connectivity Manager (SCM) products have been enhanced to provide Differential Pair Swapping capabilities that interface with the Allegro PCB Editor product.

In today's PCB designs with high-speed interfaces the use of differential pairs has become very common. We have seen customer designs having over 1000 differential pair signals on a board. Depending on the interface and the application there are number of situations were differential pairs can be optimized on a board in much the same way as standard signals. This optimization is done using swap commands in the schematic or layout tool.

The System Connectivity Manager and Allegro PCB Editor now have a feature which will enable the designers to do differential pairs swaps in more efficient way. The two scenarios supported :

Support for swapping of the (+) and (-) legs of a defined diff pair (if allowed by chips definition).

Support for swapping of the (+) and (-) legs of one differential pair with the (+) and (-) legs of another differential pair if all are contained within the same standard pin group.

Differential Pairs for a device must be defined in the chips to take advantage of the Diff Pair Swap.

Configuration is Required using PCB Librarian Expert

Define Diff Pairs in Part Developer and add the Pin Group property.

Pins with same PIN_GROUP property can be swapped.

PIN_GROUP property maps to SWAP_GROUP in PCB Editor.

As always, I'm interested in hearing in how you're using Differential Pairs, swapping, etc. in the Allegro System Architect product.

Jerry GenPart