A 20-GHz FLUX-1 superconductor RSFQ microprocessor

The first single-chip superconductor FLUX-1 microprocessor prototype with a target clock frequency of 17-20 GHz has been designed in the Rapid Single Flux Quantum (RSFQ) logic and fabricated using lowtemperature 4 kA/cm$^2$, 1.75-$\mu$m Nb/AlOx/Nb Josephson junction technology. A FLUX-1 chip represents an 8-bit deeply pipelined microprocessor with a new parallel partitioned architecture that has been developed to tolerate interconnect delays and fill long FLUX-1 pipelines with operations. A FLUX-1 chip contains 65,759 Josephson junctions on a ${\rm 10.6\,mm \times 13.2\,mm}$ die with flip-chip packaging. First FLUX-1 chips fabricated in 2001 are currently under testing at TRW