Drain Temperature Dependence on Ambient Temperature for a Cryogenic Low Noise C-Band Amplifier

A comparison between predicted and measured noise temperatures for cryogenic HEMT amplifiers is presented by using the Pospieszalski's noise model. A good agreement between predicted and measured amplifier's noise performance is obtained both at room and cryogenic temperatures. However, the predicted values overestimate noise temperature in the center part of the measured temperature range (50K - 230K). A parabolic dependence for the drain temperature with ambient temperature is proposed to obtain a better fitting to the experimental results.