Skew Enhancements

Skew Groups

The definitions of skew groups have been enhanced. In earlier versions of the product, skew groups were simply a collection of pin-pairs. A skew group can now contain an arbitrary collection of the following items:

• Electrical nets
• Differential pairs
• Buses
• Sub-buses
• Skew groups
• Pin-pairs

Constraints and Results

New constraints and results have been added for:

• Min relative length
• Max relative length
• Min relative delay
• Max relative delay

These constraints allow the length or delay of the items in a skew group to be constrained relative to a given electrical net or differential pair which has been specified to be the base item, using the new tree view context menu option Set/Unset As Base.

General

The Constraints, Constraint hierarchy sections have been updated to show how the constraint hierarchies have changed for changes to busses and skew.

A new Skew tab has been added to the spreadsheet to set skew and relative length/delay constraints, and to view the corresponding results.

Relative delay pairs are no longer used. Relative delay pairs in existing designs will be automatically upgraded into skew groups.

Skew groups are no longer displayed within bus items in the Busses branch in the tree view. All skew groups displayed in this location in earlier versions of SI Verify/PREditor XR HS have been moved to be within the Skew Groups branch.

The lengthening options in the Physical Editor have been enhanced to handle the new relative length and delay results. A full description is given in the P.R.Editor User Manual.