INTEGRATED RF AMPLIFIER BASED ON DE SQUID

Integrated radio-frequency amplifiers comprising 4-loop de SQUID, seri esly connected input coil turns, resonant capacitor parallel to the in put coil, series capacitors at the input and output ports and bias res istors have been designed, fabricated and experimentally studied, Mult iloop de SQUID with parallel loops and seriesly connected single-turn input coils placed inside each loop and integration with the input res onant matching circuit elements and with elements of de bias circuit a llows to increase signal frequency and reduce the influence of externa l noise. The amplifiers with three different capacitors have resonant frequencies 560, 656, 758 MHz and bandwidth about 50 MHz The noise tem perature of such amplifiers below 1.5 K has been measured using cold a ttenuator and room-temperature noise source. The layout comprising thr ee pairs of such amplifiers placed on the same 15x24 mm substrate was designed to increase the bandwidth over the bandwidth of individual am plifier.