1. A SUPERCONDUCTING AMPLIFIER COMPRISING A PLURALITY OF CRYOTRON STAGES, A FIRST OF SAID STAGES BEING AN INPUT STAGE AND EACH OF SAID STAGES INCLUDING A PAIR OF CRYOTRONS, EACH CRYOTRON INCLUDING A GATE AND A CONTROL GRID WHEREIN THE SAID GATES ARE CONNECTED IN SERIES IN EACH STAGE, MEANS COUPLING GRIDS OF EACH SUCCESSIVE STAGE IN SERIES ACROSS THE PAIR OF CRYOTRON GATES OF THE PREVIOUS STAGE, CURRENT GENERATING MEANS COUPLED TO THE CONTROL GRID OF EACH OF SAID CRYOTRONS FOR BIASING THE GATE OF EACH OF SAID CRYOTRONG TO A REGION WHERE RESISTANCE OF SAID GATE VARIES LINEARLY WITH CONTROL GRID CURRENT, AND A PAIR OF INDUCTANCES FOR COUPLING FLOW FREQUENCY OUTPUT SIGNALS OF SAID AMPLIFIER AS OBTAINED ACROSS A PAIR OF SAID CRYOTRON GATES TO CRYOTRON CONTROL GRIDS OF A PRIOR STAGE IN SAID AMPLIFIER IN ORDER TO SUPPRESS LOW FREQUENCY NOISE AND THEREBY MAINTAIN SAID AMPLIFIER IN ITS HIGH GAIN REGION.