The behaviour of flip-flops used as synchronizers and prediction of their failure rate

Abstract

Deals with the behavior of flip-flops, used as input synchronizers, in particular when they operate in the metastable region. It is shown first, theoretically as well as experimentally, that the average rate of system failures, due to the occurrence of metastable states (MSSs), is independent of circuit noise. A formula which describes the probability of occurrence of a metastable state has been derived. To verify the theory, measurements have been made on a flip-flop made in n-channel MOS technology. Also a method is given for predicting the average number of system failures, for a given flip-flop, occurring over a year. This method is applied to predict this average failure rate for the designed synchronizer.