Before generating the CDC report, make sure your design is fully constrained and
all clocks are defined. The report_cdc command only analyzes paths
where both the source and destination clocks are defined.
What Report CDC Analyzes
- All paths between asynchronous clocks
- Only paths between synchronous clocks that include one of the following timing
exceptions:
-
set_clock_groups -
set_false_path -
set_max_delay -datapath_only
-
If a synchronous clock pair does not have one of these exceptions, the tool assumes the path is safely timed and skips CDC analysis for that path.
Important: The CDC engine performs structural checks
only. It does not consider net or cell delays in the analysis.