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SQUID Operational Amplifier



Kent D. Irwin, Martin Huber


The nonlinear response of Superconducting Quantum Interface Devices (SQUIDs) has limited their usefulness. We propose the SQUID Operational Amplifier, which consists of several stages of SQUIDs with high open-loop current gain. When connected in a negative-feedback configuration by passing some of the output current through a feedback coil connected to the first stage, the response is linearized. An analog of the semiconductor op-amp, the SQUID op-amp can be used in superconducting equivalents of op-amp circuits such as current amplifiers, current-to-voltage converters, differentiators, and integrators. We present experimental results with a x 10 current amplifier as well as a 750 ohm} current-to-voltage amplifier which can couple directly to a room-temperature amplifier without a transformer or a feedback line.
IEEE Transactions on Applied Superconductivity


feedback circuts, SQUIDS, superconducting devices


Irwin, K. and Huber, M. (2001), SQUID Operational Amplifier, IEEE Transactions on Applied Superconductivity, [online], (Accessed July 15, 2024)


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Created February 28, 2001, Updated October 12, 2021