Intensive studies have been done in superconducting digital devices research based on rapid single flux quantum (RSFQ) logic circuits in recent years. The RS flip-flop and shift register are the key components of some important RSFQ circuits such as acquisition memories, synchronizers, and digital filters. Although some works on RTS shift registers have been reported, error-free transport of single flux quantum from one stage to another has not been clearly demonstrated. In this study, we have fabricated RS flip-flop and 4 stage shift register circuits using YBCO/Co-YBCO/YBCO ramp-edge junctions and YBCO bicrystal junctions, respectively. In order to reduce the loop inductance, we also fabricated the circuits with a ground plane placed under the junctions.
展开▼
