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We present a new design of a Rapid Single-Flux-Quantum (RSFQ) all-digital one-bit autocorrelator for submillimeter spectrometry applications, featuring 4 GHz input signal bandwidth, double oversampling quantizer, and 16 Mbps-per-channel output rate. The delay line of the autocorrelator is based on a circular shift register with XOR gates performing multiplication of the delayed and undelayed single-bit signals at every stage. The multiplication results are accumulated by room-temperature electronics after being prescaled in on-chip binary counters consisting of 10 T flip-flops per stage. We report results of experimental testing of a 16-stage autocorrelator delay line with multiplication and for a linear array of 8 low-power T flip-flop binary counters, all fabricated in HYPRES' standard 3.5 /spl mu/m 1000 A/cm/sup 2/ Nb-trilayer process. We also discuss physical and technical limits of the minimal power dissipation in RSFQ circuits.