AR# 45952

14.x Timing - Excessive delay arise from IODELAY block when it is used as Route-Thru

Description

In reviewing the timing report for the input paths, I noticed excessive delay on the input path. This excessive delay is due to the usage of the IODELAY component as a "Route-Thru".

If I change the input path to instantiate the IODELAY, the component delay is much less than when used as a "Route-Thru".

Why is there a difference?

Solution

Under specific clocking and data topology, the IODELAY is inferred and a default tap setting to ensure that this input data path has a zero hold time.

The work-around is to instantiate the IODELAY and set the tap value to a setting that helps your interface.

AR# 45952
Date 11/15/2012
Status Active
Type General Article
Tools More Less