  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.
