A Superconducting Compact C-Band Low Noise Front End With an Integral Cooler

We report a superconducting RF front-end operating in C-band, which includes a narrow band filter (pre-selector) and an amplifier on a 10×10×0.5 mm3 MgO substrate. The amplifier is a hybrid structure incorporating two Fujitsu HEMTs, and exhibits gain of 23db and 26db and minimum noise figure of 0.9db and 0.25db at room temperature and at 77 degrees Kelvin, respectively. The filter is a 3 section end-coupled microstrip design made of YBCO film on MgO substrate and exhibits less than 0.5 db insertion loss at 77 degrees K. The device is incorporated in a cryogenic mini-dewar designed for operation at microwave frequencies and cooled by a closed cycle refrigerator.