Single bit CDC

What this clock-domain-crossing interview question tests

This is a foundational digital design question about clock-domain crossing (CDC)—a core concern in any system that synchronizes signals between asynchronous clock domains. It tests whether you understand the metastability problem and can choose the right synchronization strategy given real-world constraints.

The question gives you a practical constraint: the signal changes infrequently and you have multiple destination-domain clock cycles before the next transition. This setup is designed to probe whether you can match the synchronization technique to the actual timing guarantee, rather than over-engineering or under-protecting the design. Strong answers address both the hazard and the trade-offs between latency, logic cost, and reliability.

• Metastability and settling time
• Synchronizer architectures (flip-flop chains, handshake protocols)
• Setup and hold violations across clock boundaries
• Latency vs. robustness in CDC design