Complementary Cumulative Distribution Function (CCDF) at the output of Crest Factor Reduction (CFR) should ideally display a steep fall.
When Peak Cancellation Crest Factor Reduction (PC-CFR) v6.0 is used in WCFR Standalone mode, the CCDF sometimes shows flaring.
This might be seen in some types of signal especially if the signals are oversampled. This happens due to limited precision of peak detection circuitry in the WCFR module.
In rare cases, when a signal is oversampled some peaks might go undetected.
This behavior can be seen in PC-CFR v6.0 rev3 and earlier revisions.
This is a known issue and will be fixed in PC-CFR v6.0 rev4 in Vivado 2016.1.
A patch for Vivado 2015.4 for this issue is available in the PC CFR evaluation lounge.