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AR# 17819

6.1i, Virtex-II/Pro DCM - The CLKFX jitter calculator result differs between the Architecture Clocking Wizard and the Web


Keyword: ARWZ, DCM, Wizard, online, Virtex-II, Virtex-II Pro, calculation, calculate, 6.1i, service, pack, Service Pack 2

Urgency: Hot

General Description:
With certain input parameters, the CLKFX jitter calculation result differs between the Architecture Wizard calculator and the online calculator.

The online calculator is available at:

and at:

2vp7-6 input100MHz, M=32, D=25, DFS mode=LOW
CLKIN Input Period 10.00 nS
CLKFX Output Period 7.81 nS
CLKFX Output Frequency 128.00 MHz

Online Calculator V1.1.0
- Period Jitter (pk-to-pk) 1.00 nS
- Period Jitter (unit intervals) 0.13 UI

DCM Architecture Wizard in ISE 5.2.03i
- Period Jitter (unit interval) = 0.09 UI
- Period Jitter (Peak-to-Peak) = 0.68 nS


This problem has been fixed in the latest 6.1i Service Pack, available at:
The first service pack containing the fix is 6.1i Service Pack 2.

The Architecture Wizard calculator will also be fixed in the 6.1i Service Pack 2.

NOTE: For earlier software versions, please use the results from the online calculator.
AR# 17819
Date Created 08/18/2003
Last Updated 03/28/2006
Status Archive
Type General Article