Development of a Low-power Consumption Cryogenic MMIC LNA for Immediate Connection with an SIS Mixer

We have been developing a 3-5 GHz, low-power consumption, and cryogenic low noise amplifier based on GaAs monolithic integrated circuit for multibeam radiometry applications. The low thermal dissipation also allows the MMIC LNAs being directly connected to superconductor-insulatorsuperconductor (SIS) mixers, which results in much improved compactness of the receiver frontend. The power consumption of the MMIC LNA, which is as low as 1.25 mW at ambient temperature of 4 K, is achieved by means of compromising the power consumption and the noise performance based on a cryogenic transistor model. A mixer enclosure is designed for direct connection between the SIS mixer and the LNA and the performance of the SIS/LNA combination is measured at 3 mm wavelength. Stable operation has been verified with reasonable receiver noise temperature.