An integrated 11 GHz cryogenic downconverter

A cryogenic downconverter has been designed and built to demonstrate the integration of semiconducting and superconducting components in a complete subsystem cooled by a closed cycle Stirling cryocooler. The frequency selective receiver converts 11 GHz (X-band) signals to an IF of 1000 MHz using a high temperature superconducting (HTS) microstrip input filter with a 1% bandwidth, a silicon diode mixer and a local oscillator stabilized by means of a 10 GHz HTS cavity and driven by a GaAs HEMT. The components are packaged into a cryogenic unit cooled to 60 K. Details of the system integration are presented, together with microwave and thermal test results. >