An 8-bit FLUX-1 RSFQ microprocessor built in 1.75-μm technology

This paper presents the first single-chip superconductor FLUX-1 microprocessor designed in the rapid single flux quantum logic and fabricated using 4 kA/cm², 1.75-μm Nb/AlO_x/Nb Josephson junction (JJ) technology as a result of the collaboration between SUNY Stony Brook and TRW, Inc. A FLUX-1 chip represents an 8-bit microprocessor with a parallel architecture and a target clock frequency of 17-20 GHz. It includes the pipelined instruction memory, 8 integer arithmetic-logic units interleaved with eight registers, the branch unit, and I/O ports for 5-GHz chip-to-chip communication over Nb microstrip lines on a multi-chip module carrier. The FLUX-1 instruction set consists of ∼25 arithmetic, logical, and control instructions. A FLUX-1 microprocessor chip contains 65,759 JJs on a 10.6×13.2mm² die with flip-chip packaging. First FLUX-1 chips fabricated in August 2001 are currently under testing at TRW, Inc.