CLOCK_DELAY_GROUP - 2023.2 English

Vivado Design Suite Properties Reference Guide (UG912)

Document ID
Release Date
2023.2 English

The CLOCK_DELAY_GROUP property identifies related clocks that have the same MMCM, PLL, GT source, or common driver that should be balanced during placement and routing to reduce clock skew on timing paths between the clocks.

Tip: Clock matching (via the CLOCK_DELAY_GROUP property) is intended for use with clocks from the same MMCM, PLL, or GT source.
Architecture Support
UltraScale, UltraScale+, and Versal adaptive SoCs architectures.
Applicable Objects
UltraScale, UltraScale+, and Versal adaptive SoCs architectures.
<name>: A unique string identifier used by the Vivado placer to match the delays on specified clock nets.


Verilog Syntax

Not applicable

VHDL Syntax

Not applicable

XDC Syntax
set_property CLOCK_DELAY_GROUP <name> [get_nets <clk_nets>]
set_property CLOCK_DELAY_GROUP <name> [get_nets -of_objects [get_pins <clock_buffer>/O]

Where <name> is the unique name to associate with the specified clock nets and <clk_nets> is a list of clock nets directly connected to the output of global clock buffers, that are driven by a common cell, such as an MMCM for example.

XDC Syntax Example:

# Define a clock group to reduce skew between the nets. 
set_property CLOCK_DELAY_GROUP grp12 [get_nets {clk1_net clk2_net}]

Affected Steps

  • Place Design
  • report_drc