A 16–50GHz Cryogenic LNA MMIC With 11.2K Average Noise Temperature for Radio Astronomy

This paper presents the design and characterization of a cryogenic broadband 16–50 GHz low-noise amplifier (LNA) microwave monolithic integrated circuit (MMIC) in 50nm metamorphic high-electron-mobility-transistor (mHEMT) technology for radio astronomical three-band receivers. The design targets the coverage of K-, Ka, and Q-band with low noise figure, high gain, and broadband power matching. The proposed four stage MMIC achieves more than 100% relative bandwidth with input and output port matching better than -10 dB. The effective input noise temperature is between 8–16.6K (11.2K in-band average) in the 16–50 GHz frequency range when cooled to 10K with a small-signal gain of 39.8–46.4 dB between 16–50 GHz (43.7 dB in-band average). To the best of the authors’ knowledge, this is the first demonstration of an LNA that achieves more than 100% bandwidth in the K- to Q-band frequency range at cryogenic temperatures with compatible noise temperatures to most banded cryogenic LNAs.