Low-noise device and circuit characterization at cryogenic temperatures for high sensitivity microwave receivers

The present paper focuses on the small-signal and noise characterization of microwave transistors and circuits at temperatures ranging from 290 to 90 K, in the 6-18 GHz frequency band. We here report on the measurement procedure adopted and the relevant experimental results, including also detailed linear circuit modeling to determine the temperature dependence of basic physical parameters of the tested pseudomorphic HEMT's. We have already worked at moderately low temperatures (down to 220 K) on either packaged and on wafer microwave transistors and present results at lower temperatures confirm what has been previously found.