TEMPERATURE-DEPENDENCE OF A HIGH-T-C SINGLE-FLUX-QUANTUM LOGIC GATE UP TO 50 K

Basic characteristics of a simple single-flux-quantum (SFQ) logic gate using high-T-c material and Josephson junction (NdBa(2)Cn(3)O(7-delta ) and focused ion beam junction) have been investigated. The logic gat e consists or an rf-superconducting quantum interference device (rf-SQ UID) and a de-SQUID. In the logic gate, elementary SFQ logic operation s, Such as generating SFQ (dc/SFQ) and providing simultaneous readout (SFQ/dc), have been confirmed up to 50 K. The temperature dependencies of the output voltage level and the critical current-normal resistanc e (IcRn) product were compared, and the decreasing tendency of the out put voltage level for increasing temperature was found to be more rapi d than that of the IcRn, product. (C) 1998 American Institute of Physi cs.