In the Floorplan Editor/PACE, the following standards can be placed on a low cap (LC) IOB site:
(LVDS_25, LVDSEXT_25, LVDS_25_DCI, LVDSEXT_25_DCI, ULVDS_25, and LDT_25)
This breaks the rules for Differential Termination in the Virtex-4 User Guide. Which one is correct?
There should be DRC errors in Floorplan Editor/PACE. This problem has been fixed in PlanAhead. Please use PlanAhead to have a correct DRC.
For more information about Differential Termination, refer to Chapter 6 of the Virtex-4 User Guide :