| 摘要 |
A superconducting quantum interference device (SQUID) is direct current biased through physical connections asymmetric to, and preferably maximally asymmetric to, the two Josephson junctions. The asymmetric SQUID so created is, responsively to such physical asymmetry, biased for operation in the linear region of the input magnetic flux/output (voltage or current) device response curve. A resistance of specified value is connected in parallel, or shunt, to the parasitic bridge capacitance of the asymmetric SQUID in order to minimize hysteresis. Two asymmetric SQUIDS of opposite asymmetry are serially connected as a push-pull linear amplifier stage which exhibits zero output (voltage or current) at zero input magnetic flux, and which is specifiable in parameters of construction so as to exhibit optimum linearity of response about such point. Plural successive such linear amplifier stages are connected by an LC filter, which filter is lowpass to the Josephson oscillation frequency, in order to form a linear amplifier entirely with the cyrogenic environment and with a bandwidth of the order to D.C. to 109 Hertz.
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