A 16 – 50 GHz Cryogenic LNA MMIC With 11.2 K 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 50 nm 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 8–16.6 K (11.2K 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 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.