Architecture and Design of an 8-bit Flux-1 Superconductor Rsfq Microprocessor

The first single-chip superconductor FLUX-1 microprocessor has been designed in the Rapid Single Flux Quantum (RSFQ) logic and fabricated using 4 kA/cm, 1.75μm Nb/AlOx/Nb Josephson junction technology as a result of the collaboration between SUNY Stony Brook and TRW, Inc. A FLUX-1 chip represents an 8-bit deeply pipelined microprocessor prototype with a target clock frequency of 17-20 GHz. A new parallel partitioned architecture has been developed in order to tolerate interconnect delays and fill long FLUX-1 processor pipelines with useful instructions. The processor includes the 16 x 32-bit pipelined instruction memory, 8 integer arithmetic-logic units interleaved with 8 registers, the branch unit, and I/O ports for 5-GHz chip-to-chip communication over Nb microstrip lines on a chip carrier. The FLUX-1 instruction set consists of ~25 arithmetic, logical, and control instructions. A FLUX-1 microprocessor chip contains 65,759 Josephson junctions on a 10.6 mm x 13.2 mm die with flip-chip packaging. First FLUX-1 chips fabricated in August 2001 are currently under testing at TRW, Inc.