Vector measurements of microwave devices at cryogenic temperatures

A real-time method to de-embed S-parameter measurements of MIC (microwave integrated circuit) devices operated at 77 K is presented. An apparatus to immerse the devices into liquid nitrogen and microstrip jigs that survive the extreme temperature drop were constructed in order to apply the through-reflect-line calibration technique to measurements over a frequency band from 2.5 GHz to 20 GHz. Measurements of both an interdigitated capacitor and a GaAs MESFET cooled in the liquid nitrogen bath are shown for these frequencies.<<ETX>>