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AR# 8948

Virtex-E, LVPECL and LVDS - The negative (N-side) differential signal input does not show up in the design


A design is done using the differential inputs (LVPECL or LVDS). However, when I view the implemented files, the N-side input does not exist (pad report, FPGA Editor, Floorplanner, etc).


When using differential signaling (LVDS or LVPECL), only the P-side of the signal is analyzed by the Xilinx tools. If the tools see that the P-side is configured, the Placer and BitGen will automatically account for this and correctly configure the device. 


However, the N-side IOB cannot be viewed in tools such as FPGA Editor.

AR# 8948
Date Created 08/21/2007
Last Updated 05/14/2014
Status Archive
Type General Article