Applied Superconductivity

Single flux quantum one-decimal-digit RNS adder

Nada Vukovic, M. J. Feldman

Published Oct 1, 1999• 1 citation

Abstract

Residue number system (RNS) arithmetic has a promising role for fault-tolerant high throughput superconducting single flux quantum (SFQ) circuits for digital signal processing (DSP) applications. We have designed one of the basic computational blocks used in DSP circuits, one-decimal-digit RNS adder. A new design for its main component, the single-modulus adder, has been developed. It combines simple and robust RSFQ elementary cells, both combinational and sequential. The central units are a circular shift register, a code converter, and the clock control circuitry. Our mod5 adder employs 195 Josephson junctions, consumes 50 μW of power, and occupies an area of less than 2 mm2. Chips were fabricated at HYPRES, Inc. using 1 kA/cm2 low-Tc Niobium technology. The mod5 adder was successfully tested at low speed, and gave experimental bias margins of ±26%.

DOI: 10.1016/s0964-1807(99)00018-6

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