SIGNAL RESOLUTION OF RSFQ COMPARATORS

We have designed and tested a Rapid Single-Flux-Quantum (RSFQ) circuit for experimental measurement of the fluctuation-induced threshold unc ertainty of switching of SFQ comparators, which are the most essential single components of the RSFQ logic devices, analog-to-digital conver ters, and digital SQUIDs. Statistical density of the switching events in comparators using externally-overdamped Nb-trilayer Josephson junct ions has been found to be in a nice agreement with the distribution wh ich follows from a simple theory based on a time-dependent harmonic-os cillator model of the device. Width of the distribution (i.e., the sin gle-shot current resolution of the comparator) measured as a function of temperature in the range 1.7-4.2 K corresponds to fundamental (ther mal/quantum) fluctuations, with no evidence of excess noise sources.