Dynamic CDC Verification: Efficient Approaches for in-house Flows

Verifying the functionality of a design running on different clock domains is a challenging task; Static CDC ensures that a viable synchronization scheme is used for a given design so that stable and coherent data is observed. But static CDC relies on constraints which might hide synchronization issues, and fails to catch functional bugs in cases where a design is not tolerant to differences in the timing of received data caused by metastable events inside a synchronizer. This is where Dynamic CDC comes into play. The presentation will cover what Dynamic CDC is, why it’s important, and the challenges in scaling the verification efforts with large designs. A (free) approach for a Dynamic CDC flow with a custom synchronization model will be presented and proposed as an alternative for proprietary flows, and the tradeoffs between the two flows will be covered. The presentation will focus on the considerations needed for modeling metastability in synchronizers - including optimizing for simulation speed, repeatable and unique randomization, and worst-case modeling - as well as the effects that even properly synchronized metastable events may have on the design.

Christian is a Digital Design engineer at semify, passionate about all things IC related. His professional experience includes RTL design for modules like multi-clock protocol bridges, peripherals for bus-based systems, and design and implementation of custom RISC-V extensions for hardware acceleration of compression algorithms as part of the European Union sponsored TRISTAN project. Christians current work includes SoC verification, where he primarily focuses on CDC verification and Gate Level Simulation.