Title :
Signal resolution of RSFQ comparators
Author :
Filippov, T.V. ; Polyakov, Y.A. ; Semenov, V.K. ; Likharev, K.K.
Author_Institution :
State Univ. of New York, Stony Brook, NY, USA
fDate :
6/1/1995 12:00:00 AM
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.<>
Keywords :
Josephson effect; analogue-digital conversion; current comparators; signal resolution; superconducting device noise; superconducting logic circuits; superconducting switches; 1.7 to 4.2 K; Josephson junction switching dynamics; Nb; RSFQ comparators; RSFQ logic devices; analog-to-digital converters; digital SQUIDs; externally-overdamped Nb-trilayer Josephson junctions; fluctuation-induced threshold uncertainty; quantum fluctuations; rapid single-flux-quantum circuit; signal resolution; single-shot current resolution; switching event statistical density; thermal fluctuations; time-dependent harmonic-oscillator model; Analog-digital conversion; Circuit testing; Current measurement; Josephson junctions; Logic devices; Logic testing; Noise measurement; SQUIDs; Signal resolution; Switching circuits;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
