Cryogenically Coolable HEMT Amplifiers in the Frequency Range 2-45 GHz

The design and performance of cryogenically coolable HEMT amplifiers in the frequency range from 2 GHz to 45 GHz is presented. Noise temperatures of 15 K at 15 GHz, 30 K at 32 GHz and 35 K at 43 GHz have been achieved. A semi-empirical approach based on the work of Pucel [5], Rhode [4] and Pospieszalski [3] is used for the derivation of the cyogenically cooled HEMT´s noise parameters. An empirially developed formula for the equivalent temperature Td at 20 K is given. Good agreement is obtained between measurements and the model.