Intel® Quartus® Prime Pro Edition User Guide: Timing Analyzer

ID 683243
Date 10/02/2023
Document Table of Contents Specifying I/O Interface Uncertainty

Virtual clocks are recommended for I/O constraints because they most accurately represent the clocking topology of the design. An additional benefit is that you can specify different uncertainty values on clocks that interface with external I/O ports and clocks that feed register-to-register paths inside the FPGA.