This sample calculation uses a 50 MHz clock, a 10 MHz average incoming data rate, and the available extra settling time is the independent parameter. Later, we'll be adding calculation done for other types of flip-flops from other device manufacturers. This will allow a comparison of metastable state resolution performance. Also, we'll be adding a program to calculate MTBF's for all the flip-flops we have parameters for as well as a custom setting. Since the flip-flops in a synchronizer will be physically close, this is probably very conservative.
Metastability is unavoidable in asynchronous systems.
However, using the formulas and test measurements supplied here, designers can calculate the probability of failure. Design techniques for minimizing metastability are also provided. Description of metastable states, measurement techniques, tables of metastable parameters, and a summary graph. After a definition of a metastable state, a test circuit is provided, its responses analyzed, and test results given. Examples show the influence of metastability on the response of asynchronous circuits and measures for improving reliability are assessed.