Applications of synchronized switching in series-parallel-connected Josephson junctions

It was found that series-parallel-connected Josephson junctions exhibit synchronized switching. The structure used makes possible a Josephson device with an output voltage equal to a multiple of the gap voltage. As a result one of the structures becomes almost the same as a direct-coupled-logic gate. However, multiple junctions are required and circuit parameters in the gate must be optimized for synchronized switching. In experiments, the synchronized switching of all junctions connected in series and parallel were demonstrated. A high-voltage gate was constructed using synchronized switching and was applied to a cell driver in a Josephson memory circuit. The output voltage was four times the gap voltage, and a fast access of 590 ps was obtained. Experimental results are described for three applications: a memory cell driver, a regulator, and an interface circuit