Sperry Corporation

Tsing-Chow Wang

Richard M Josephs

Peter L Young

Barry F Stein

William E Flannery

A high gain Josephson junction logic circuit is provided. The novel circuit comprises a high gain non-linear threshold input Josephson junction logic circuit which is coupled to a high gain Josephson junction amplifier. The high gain input circuit provides the capability of driving a larger number of output circuits or employing a larger number of input signals.

High gain non-linear threshold input Josephson junction logic circuit

A superconductive Josephson junction high density memory array is provided. Each memory cell in the array comprises a two branch superconducting interferometer storage loop which has only a single Josephson junction device in one of the branches. The Josephson junction devices are mounted on a substrate having a patterned ground plane. The ground plane pattern is provided with holes or apertures which surround the Josephson junction devices so that the control current of the control lines couple with the tunnel junctions of the Josephson junction devices but not with the ground plane. This structural arrangement provides a threshold characteristic for the single Josephson junction device which is symmetrical to the gate current, thus, may be easily switched to two current states indicative of two logic states.

High density Josephson junction memory circuit

A Josephson junction latch circuit is provided which has an AND gate having plural inputs and a single output. The output of the single AND gate is directly coupled to a Josephson junction flux storage loop capable of storing flux indicative of the output of the AND gate. A Josephson junction sense line is provided capable of sensing the flux condition of the flux storage loop. The sense line is directly coupled to amplifying gates which produce amplified true and complement quantities whenever the sense line is actuated.

Josephson junction latch circuit

A single Josephson junction device is arranged in a single branch which comprises an external source resistor connected in series with an output resistor and a Josephson junction device. An input node and an input resistor are in series and connected to the node between the output resistor and the Josephson junction device. Voltage signals applied to the input voltage node are amplified by connecting a high gain voltage output in parallel with the output resistor and providing sensing means for sensing the voltage output across the output resistor only when the Josephson junction device is switching from its low impedance state to its high impedance state.

High gain Josephson junction voltage amplifier

During the manufacture of Josephson superconducting devices, it is necessary to provide on a substrate a base electrode, a counter electrode and a small tunnel barrier area therebetween. A novel method of making all three of these active elements in the same vacuum chamber without having to remove the substrate from the vacuum chamber is provided so that the tunnel barrier area is accurately made to a predetermined size and without the danger of contamination. The novel structure is made as a substantially planarized laminate in the vacuum chamber and the tunnel barrier area is defined in a supplemental step.

Method of making improved tunnel barriers for superconducting Josephson

A Josephson junction AND gate logic circuit is provided which has an enhanced and improved operating window area. The circuit comprises two parallel branches one for the input and one for the output connected between a biasing current source and a ground or reference voltage. The input branch is provided with a first branch resistor, a third Josephson junction and an interferometer in series between the current source and ground. A plurality of input gate signal lines connects to the interferometer and a sink resistor is connected in parallel with the interferometer. When the input current signals collectively exceed a predetermined level, the two Josephson junctions in the interferometer switch ON and assume the high impedance state. The input current and biasing current is diverted into the output branch causing the second Josephson junction in the output branch to switch ON. The biasing current in the output branch creates a high-gain current to the load circuit connected in parallel with the second Josephson junction.

Four Josephson junction direct-coupled and gate circuit

A two branch, three Josephson junction gating circuit is provided with a plurality of inputs to enable the circuit to be operated as a high-gain logic OR gate. The circuit is arranged to provide a larger operating window area and to provide an improved and optimized gain characteristic by selectively switching ON the Josephson junctions in the circuit.

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Norristown, PA, United States of America

Tsing-Chow Wang