DESIGN AND PERFORMANCE OF LOW-NOISE HYBRID SUPERCONDUCTOR SEMICONDUCTOR 7.4 GHZ RECEIVER DOWNCONVERTER

Low noise receivers play critical role in space applications. Thin fil m high-crtical -temperature-superconducting (HTS) passive circuits wer e combined with GaAs microwave devices to achieve ultra low noise and small size receiver downconverter at 77 K. HTS pre-select filter, a cr yogenic mixer, and a hybrid oscillator with an HTS resonator were desi gned, fabricated and interconnected to produce a low-noise hybrid supe rconductor/semiconductor 7.4 Ghz microwave reciever. When cooled to 77 K, the downconverter plus cables inside a cryogenic refrigerator had a noise figure of approximately 0.7dB with convdersion gain of 18 dB. I n addition to reduce noise figure, advantages of small size and low po wer consumption are obsereved due to the use of HTS circuits in the do wnconverter.