I am implementing a design which contains a Mixed-Mode Clock Manager (MMCM) generated in IP catalog.
During place_design and route_design, I receive the following critical warning:
What is the issue here and how can I correct it?
The reason for the critical warning is that there is no connection for the feedback net of the MMCM.
When generating an MMCM, the default option for the clocking feedback source is "Automatic Control On-Chip".
However, when you remove the BUF(BUFG/BUFH) of the output clock clk_out1, you need to connect the clocking feedback net by yourself.