Logic Operation of SFQ Circuit Elements Made of YBCO Junctions
YBa2Cu3O7-x(YBCO) ramp-edge junction technologies have been developed for fabricating high-operating-temperature SFQ(Single Flux Quantum) circuits. The Ic(critical current) spread that is the key parameter for integrating junctions could be decreased to 8% for a 1000-junction array that was formed on a groundplane. The background technologies that enabled this uniform junction characteristic are precise control of the counter-electrode deposition-conditions and deposition of the extremely smooth multiplayer that showed the roughness as small as 2 nm. Based upon these ramp-edge junction technologies, oxide SFQ-circuit-elements were fabricated and their logic operations were investigated. SFQ circuit elements such as a confluence buffer, a set-reset flipflop, and a toggle flipflop have been fabricated and their logic operations were measured by using an SFQ-dc converter. Both toggle flipflops that have one output and two outputs have been fabricated. These circuits could be operated up to the temperature of near 60 K under finite operating margins. These experimental results enable us to further develop fuctional and much more integrated SFQ circuits.
P. VINCENZINI and A. RIGAMONTI
Y. Tarutani et al., "Logic Operation of SFQ Circuit Elements Made of YBCO Junctions", Advances in Science and Technology, Vol. 47, pp. 170-179, 2006