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.