Trw Limited

Robert D Sandell

Arnold H Silver

Hugo W Chan

Richard R Phillips

Gregory Steven Lee

Andrew Donovan Smith

Randy Wayne Simon

James M Murduck

Michael Leung

A multi-state Josephson memory in a superconductor integrated circuit includes a plurality of superconductive quantum interference device (SQUID) memory cells 2 each having a SQUID 4 characterized by a SQUID loop inductance L and a junction critical current I.sub.c, which determine the number of memory states that can be stored in the SQUID 4. A gate current I.sub.g is transmitted to the superconductive inductors 6 and 8 of the SQUID 4 to perform a read operation by crossing a designated number of current threshold boundaries corresponding to the memory state stored in the SQUID, so that the Josephson junction 12 of the SQUID 4 generates a number of pulses corresponding to the memory state. A control current I.sub.con writes data to the SQUID 4 through a control current input 16, and is preferably magnetically coupled to the SQUID 4 through superconductive inductor pairs 18, 6 and 20, 8. In a preferred embodiment, a plurality of SQUID memory cells 70a, 70b, . . . 70f are arranged in a plurality of columns and rows with column select inputs 72, 74 and row select inputs 76, 78 and 80. Digital-to-analog converters 86 and 88 are preferably provided to convert a binary digital input into the analog control current I.sub.con, the magnitude of which is designed to cross a number of current threshold boundaries corresponding to the digital input. A plurality of single flux quantum counters 112 and 114 are preferably connected to count the number of Josephson pulses from the SQUID memory cells 70a, 70b, . . . 70f to generate a count of the pulses as the memory output. In a preferred embodiment, the memory outputs from the single flux quantum counters 112 and 114 are fed back into the input digital-to-analog converters 86 and 88, respectively, to form a non-destructive readout.

Multi-state Josephson memory

A multi-layer microstrip structure includes a substrate and a first superconducting layer deposited on the substrate. A first dielectric layer, made at least partially of benzocyclobutene (BCB), is deposited on the first superconducting layer. Additional superconducting dielectric and superconducting layers can be employed. Preferably the superconducting layers are made from niobium. The multilayer microstrip structure is ideally suited for use in passive circuit components of microwave circuits and in multi-chip modules.

Superconducting multi-layer microstrip structure for multi-chip modules

A high-performance superconducting digital-to-analog (D/A) converter providing asynchronous high-speed, low-power D/A conversion. The high-performance superconducting D/A converter includes a double-junction superconducting quantum interference device (SQUID) voltage divider circuit, which generates a series of discrete binary voltages, and a double-junction SQUID voltage selector circuit, which selects the binary voltages in accordance with a digital input signal. The currents generated by the selected binary voltages are added together to produce an analog output current that represents the digital input.

High-performance superconducting digital-to-analog converter employing

A superconducting infrared photodetector employing SQUID (Superconducting Quantum Interference Device) measurement of fluxon flow in thin superconducting granular films to provide sensitive, low-noise detection of infrared radiation. The superconducting infrared photodetector includes a plurality of superconducting detector elements connected in parallel or series, means for supplying a bias current to the detector elements, and a digital or analog SQUID readout circuit. Each detector element includes a thin granular film of superconducting material which forms a randomly connected array of weakly coupled superconductors. The weakly coupled superconductors promote the formation of oppositely-polarized fluxons, which are driven to opposite sides of the film when subjected to the bias current. Incident radiation causes an increase in this fluxon flow, generating a voltage change. The voltage change is measured by the SQUID readout circuit to provide a sensitive, low-noise measurement of the amount of radiation incident on the detector elements.

Sensitive, low-noise superconducting infrared photodetector

A Josephson junction and a method for its fabrication in which a laminated junction layer is formed in situ on the side edge of a base electrode contact. The laminated junction layer forms the Josephson junction of the present invention and includes an insulating or barrier layer sandwiched between a superconducting base electrode and a superconducting counter electrode. The Josephson junction is formed on the side edge of the base electrode contact to allow very small junction areas to be fabricated using conventional optical lithographic techniques, such as photolithography. The laminated junction layer is formed in situ, with the three layers of the laminated junction layer being formed successively without removing the device from the controlled atmosphere of the deposition system, to prevent contamination of the junction region.

Submicron Josephson junction and method for its fabrication

An analog-to-digital converter quantizer and bidirectional counter using superconducting quantum interference devices (SQUD's) as the principal elements. A double-junction non-latching SQUID is used as a quantizer to produce unipolar output pulses on two different output lines, indicative of positive and negative increments of change in an analog signal current. The unipolar pulses are then counted in a bidirectional counter that employs double-junction non-latching SQUID's as counter stages and as logic gates for the propagation of carry and borrow signals from stage to stage.

Superconducting analog-to-digital converter with bidirectional counter

An analog-to-digital converter quantizer and bidirectional counter using superconducting quantum interference devices (SQUID's) as the principal elements. A double-junction non-latching SQUID is used as a quantizer to produce unipolar output pulses on two different output lines, indicative of positive and negative increments of change in an analog signal current. The unipolar pulses are then counted in a bidirectional counter that employs double-junction non-latching SQUID's as counter stages and as logic gates for the propagation of carry and borrow signals from stage to stage.

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Manhattan Beach, CA, United States of America

Robert D Sandell