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AR# 7775

2.1i Foundation - LOCKED signal does not go high on CLKDLL during Timing Simulation

Description

Keywords: dll, lock, simulation, high, Virtex, fndtn

Urgency: Standard

General Description: During Timing Simulation of the CLKDLL, the LOCKED output signal never goes high. This limitation is the result of simulation resolution in the Foundation Logical Simulator . Currently the resolution is limited to 100ps. In order for the CLKDLL to lock the resolution must be set to 1ps.

Solution

There are two workarounds:

1- Manually apply stimulus to the CLKDLL LOCKED signal to
drive it high at 300ns. This will allow more than enough time
to model the LOCKED signal on the board.

2- Use a third party simulator such as Modelsim where the
resolution can be set to 1ps.
AR# 7775
Date Created 09/27/1999
Last Updated 03/12/2002
Status Archive
Type General Article