relationship between flopping and meta-stability

Question

While doing clock domain conversions (rate matched) we usually double flop the data to avoid meta-stable states. Double flopping just reduces the probability of meta-stability. Triple flopping will reduce it further.

How to calculate the probability/relationship between meta-stability and number of clock domain flops used?

Answer 1

The canonical answer to metastability queries always involves referring to articles written by the late, great, Peter Alfke. In particular, the XAPP094 appnote - don't worry about the age of it, the theory is still the same.

There are also numbers for some more recent families available - although I can't see anything for the 6 and 7 series as yet.