An elementary logic circuit employing superconducting Josephson tunneling gates

The design and experimental investigation of a simple logic circuit employing Josephson tunnel junctions as the switching elements is described. The design utilized matched transmission lines as signal carriers. The physical layout was simulated on a computer with a model consisting of 3 Josephson gates and 28 transmission line segments. Results of both quasi-static and high speed testing were found to be in essential agreement with theoretical expectations; only dynamic results are presented here in detail. The experimental circuit had gates with 165 ps risetimes, and in the high speed investigation, was operated with bursts of 700 ps risetime pulses tightly spaced so as to simulate a repetition rate of ∼1 GHz.