A three Josephson junction direct coupled isolation device

A new type of current switching logic device using three Josephson junctions is described. This device allows the simultaneous optimization of both the gain and the operating margin. It shows an enhanced threshold curve compared with that of the Direct Coupled Logic (DCL) isolation device and the Josephson Atto-Weber Switch (JAWS). Design optimization and simulation results are presented. The device shows an almost square current transfer curve indicating good input and output isolation. The dependence of delay on fan-out is also discussed. For a fan-in of 1 and a fan-out of 3, the switching delay is 38 ps with a power dissipation of 3.6 µW.