Noise figure of HTS JJ MMIC downconverter at 12 GHz

A YBa/sub 2/Cu/sub 3/O/sub 7- delta / (YBCO) step-edge microbridge JJ (Josephson junction), two 12-GHz YBCO microstrip bandpass filters, a 1-GHz YBCO filter, and current bias and voltage monitor circuits were successfully combined on a 20-mm*20-mm MgO substrate and integrated into a frequency downconverter for receiving DBS (direct broadcast satellite) signals. The YBCO downconverter and the GaAs low-noise IF (intermediate frequency) amplifier were combined in a microwave cryostat. The dependence of mixing signals on temperature and LO (local oscillator) input power was measured. The conversion gain and the noise figure corresponding to the YBCO downconverter package were -14.5 dB and 12.2 dB, respectively, at 15 K and low LO power (-25 dBm). The first demonstration of the HTS (high-temperature superconductive) subsystem, i.e. the monolithic YBCO downconverter, shows potential for applications in mobile radio communications and satellite broadcasting.<>