Class-B cable-driving SQUID amplifier.

We suggest a SQUID amplifier configuration with improved power efficiency, for applications where cooling budgets are limited, in particular superconducting detector array readouts in space observatories. The suggested two-SQUID configuration keeps one SQUID in a zero-voltage state during a half-cycle of the input while the other SQUID generates voltage. For the other half-cycle the roles of the SQUIDs are reversed. The circuit is an electrostatic dual of a transistor-based amplifier operating in class-B. A proof-of principle demonstration at T = 4.2 K is presented.