AR# 12667


Virtex-II/-II FPGA Pro, Virtex-4 FPGA DCM - What is the output jitter for the CLKFX? (Jitter Calculator)


What is the output jitter for the CLKFX? The parameter CLKOUT_PER_JITT_FX is listed in the Data Sheet under DC and Switching Characteristics -> DCM Timing Parameters (or Output Clock Jitter). However, the value is not listed.

NOTE: You can access the data sheets at:


The CLKFX jitter value depends on the frequency, the CLKFX_MULTIPLY (M) value, and the CLKFX_DIVIDE (D) value.

To obtain the value for Virtex-II FPGA, Virtex-II Pro FPGA, or Virtex-4 FPGA, use the CLKFX Jitter Calculator which is available in the Architecture Wizard.

NOTE: Generally, using CLKDV or CLK2X allows better output jitter than using CLKFX.
AR# 12667
Date 12/15/2012
Status Active
Type General Article
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