A single QFP timing discriminator

A root-mean-square (RMS) time jitter of 380 fs has been demonstrated in a single quantum flux parametron (QFP) race arbiter circuit with approximately 60-ps-risetime signal inputs. Because of the simple relationship between the QFP current comparator and the race arbiter, it is possible to make direct comparison of the time jitter and current noise results. The measured current noise in a QFP current comparator implies that, for a signal risetime of 10 ps, a time jitter of approximately 200 fs is expected for this race arbiter circuit. Circuit modeling suggests that an optimized design can achieve approximately 100-fs time jitter.<>