Title :
SQUID operational amplifier
Author :
Irwin, K.D. ; Huber, M.E.
Author_Institution :
Nat. Inst. of Stand. & Technol., Boulder, CO, USA
fDate :
3/1/2001 12:00:00 AM
Abstract :
The nonlinear response of Superconducting Quantum Interference Devices (SQUIDs) has limited their usefulness. We describe 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, and differentiators. We present experimental results with a ×10 current amplifier as well as a 750 Ω current-to-voltage amplifier which can couple directly to a room-temperature amplifier without a transformer or a feedback line
Keywords :
DC amplifiers; SQUIDs; convertors; feedback amplifiers; operational amplifiers; superconducting integrated circuits; 750 ohm; SQUID operational amplifier; current amplifiers; current-to-voltage amplifier; current-to-voltage converters; differentiators; direct coupling; feedback coil; high open-loop current gain; linearized response; negative-feedback configuration; output current; room-temperature amplifier; Bandwidth; Circuits; Costs; Feedback; Inductance; Operational amplifiers; Resistors; SQUIDs; Superconducting coils; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
