IEEE Transactions on Applied Superconductivity

Signal resolution of RSFQ comparators

Timur V. Filippov, Y.A. Polyakov, Vasili K. Semenov, K. K. Likharev

Published Jun 1, 1995• 73 citations

Abstract

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

DOI: 10.1109/77.403031

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