Two correctly synchronised signals can still fail together: if they come from the same source event, cross through separate synchronisers, and recombine in the destination domain, the two paths can arrive a cycle apart and the destination briefly acts on a combination that never existed. These four lessons define that failure, show how it arises with a simulated waveform, explain what structural analysis reports, and give the standard fixes.
Lesson | After it you can... |
|---|---|
Define reconvergence and separate it from metastability. | |
Recognise the RTL patterns and read the glitch waveform. | |
Say what a structural report means and what the reviewer must answer. | |
Pick the right fix and name its trade-off. |
Study in order: the definition, then the patterns and waveform, then the report meaning, then the fixes.
Yes. The synchronisers guarantee each bit settles, not that the two bits arrive together. If the paths sample the source change on different destination edges, the destination sees the new value of one with the old value of the other for a cycle.