Timing Closure Challenges in Xilinx Vivado
Documenting the iterative process of meeting setup and hold constraints across corner cases for an FPGA-based reliability monitor.
Timing closure on a non-trivial FPGA design is rarely a single-pass exercise. Each iteration of the reliability monitor introduced new observation paths, and each new path widened the timing report.
The first wins came from rethinking pipeline depth around the monitor's comparison logic - adding registers where fan-out exploded, and tightening clock-domain crossings with proper synchronizers.
What remained were the corner cases: slow-slow process corners at high temperature, where setup margins evaporated. Constraining false paths and applying multicycle exceptions only where physically justified turned a red report green without hiding real violations.
By Tal Moyal · Hardware, FPGA & RTL Design
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