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Size a synchronizer from an MTBF target

MediumClock and Reset DomainsSystemVerilog

A stable one-bit asynchronous level enters a 500 MHz destination domain. The library MTBF calculation shows that a two-stage synchronizer misses the product reliability target. The source toggle rate and destination clock cannot change. Which design decision is technically justified?

Choose one

Answer choices

  1. A. Add exactly one third stage because every three-stage synchronizer has effectively infinite MTBF.
  2. B. Keep two stages because the two-flop pattern guarantees that metastability cannot reach downstream logic.
  3. C. Replace the stages with independent rising-edge and falling-edge samplers and OR their outputs.
  4. D. Add destination-domain synchronizer stages until the library MTBF equation meets the allocated target, then account for the added detection latency.
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