Phase Shift in Clock Reports - 2025.2 English - UG906

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)

Document ID
UG906
Release Date
2025-12-10
Version
2025.2 English
You can find clock phase shift information in the Clock Report, which you generate using the report_clocks command. When an MMCM/PLL clock is phase-shifted with PHASESHIFT_MODE set to LATENCY, the tool marks the auto-derived clock with attribute S.

In the Generated Clocks section of the clock report, you see the pin phase shift the tool accounts for in the MMCM/PLL insertion delay.

Note: The report only includes the delay from the auto-derived clock phase shift. It doesn’t include the phase shift the tool includes in the MMCM/PLL insertion delay.

In the following example below, the MMCM has PHASESHIFT_MODE set to LATENCY. The auto-derived clock clk_out1_clk_wiz_0 has no phase shift defined for the MMCM pin CLKOUT0, while clk_out2_clk_wiz_0 includes a –90 degree phase shift defined for CLKOUT2.

Attributes
  P: Propagated
  G: Generated
  A: Auto-derived
  R: Renamed
  V: Virtual
  I: Inverted
  S: Pin phase-shifted with Latency mode


Clock               Period(ns)  Waveform(ns)    Attributes  Sources
clk_in1             10.000      {0.000 5.000}   P           {clk_in1}
clk_out1_clk_wiz_0  10.000      {0.000 5.000}   P,G,A       {clknetwork/inst/mmcme3_adv_inst/CLKOUT0}
clk_out2_clk_wiz_0  10.000      {0.000 5.000}   P,G,A,S     {clknetwork/inst/mmcme3_adv_inst/CLKOUT2}


====================================================
Generated Clocks
====================================================

Generated Clock     : clk_out1_clk_wiz_0
Master Source       : clknetwork/inst/mmcme3_adv_inst/CLKIN1
Master Clock        : clk_in1
Multiply By         : 1
Generated Sources   : {clknetwork/inst/mmcme3_adv_inst/CLKOUT0}

Generated Clock     : clk_out2_clk_wiz_0
Master Source       : clknetwork/inst/mmcme3_adv_inst/CLKIN1
Master Clock        : clk_in1
Multiply By         : 1
Pin Phase Shift(ns) : -2.5  (-90 degrees)
Generated Sources   : {clknetwork/inst/mmcme3_adv_inst/CLKOUT2}