Challenges In Verification Of Clock Domain Crossings

Insights into the three dimensions of complexity for making designs CDC-safe.


Emerging systems have three dimensions of complexity when it comes to making them CDC-safe. First, the number of asynchronous clock domains in designs can range from the tens to the hundreds for complex systems with many components. Second, the master clock frequencies vary per component. It is not uncommon for the ratio between the fastest and the slowest clocks to be greater than 10. Third, the clock frequencies themselves can change dynamically during the course of chip operation to save power. As a result, CDC verification becomes critical to ensure that metastability is not introduced in the design.

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