Noise Performance of a Cryogenically Cooled 94 GHz InP MMIC Amplifier and Radiometer

We have developed an ultra-low noise 94 GHz MMIC amplifier using InGaAsfInAlAsfInP transistor technology. The MMIC designs incorporate a single transistor stage with input and output matching networks as well as gate and drain bias networks. Two MMICs have been incorporated into a single housing providing 10 dB of gain. At room temperature, the integrated amplifier has a measured noise of 365 K (3.5 dB) at 94 GHz. Cryogenic measurements have been performed using a direct detection total power radiometer with all amplification provided by MMIC amplifiers. The noise figure for the entire radiometer has been measured to be 78 K (1.01 dB). The noise figure for the cryogenic InP MMIC 2-stage amplifier unit has been measured to be 5 1 K (0.69 dB) with a low power consumption of 0.84 mW per stage. The stability of the radiometer with a 4 GHz bandwidth, is characterized by a power spectrum with a "1/fknee" frequency of 45 Hz.