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

ID 683068
Date 2/21/2024
Document Table of Contents

1.1.5. Multicycle Path Analysis

Multicycle paths are data paths that require either a non-default setup or hold relationship, for proper analysis.

For example, a register may be required to capture data on every second or third rising clock edge. An example of a multicycle path between the input registers of a multiplier and an output register where the destination latches data on every other clock edge.

Figure 19. Multicycle Path

A register-to-register path used for the default setup and hold relationship, the respective timing diagrams for the source and destination clocks, and the default setup and hold relationships, when the source clock, src_clk, has a period of 10 ns and the destination clock, dst_clk, has a period of 5 ns. The default setup relationship is 5 ns; the default hold relationship is 0 ns.

Figure 20. Register-to-Register Path and Default Setup and Hold Timing Diagram

To accommodate the system requirements you can modify the default setup and hold relationships by specifying a multicycle timing constraint to a register-to-register path.

Figure 21. Register-to-Register Path

The exception has a multicycle setup assignment of two to use the second occurring latch edge; in this example, to 10 ns from the default value of 5 ns.

Figure 22. Modified Setup Diagram