Design of Cryogenic LNAs for High Linearity in Space Applications

This paper presents a 2 GHz low noise amplifier (LNA) implemented in 180 nm complementary metal oxide semiconductor (CMOS) technology designed for cryogenic temperatures as well as its measurement results at both room temperature and 77 K. A modified approach to classical LNA design has been adopted. The matching of the LNA has been performed by external discrete components such that $S_{11}$ and $S_{22}$ of the LNA between 2.025 and 2.12 GHz (designated for space communications) are below -10 dB at both 77 K and 297 K. At 77 K, the designed LNA achieves 18 dB gain, 35.4 K noise temperature, and 3 dBm IIP3. IIP3 performance of the LNA at cryogenic temperatures has been analyzed in particular, and the linearity improvement by using the proposed approach has been demonstrated. Moreover, the designed LNA was irradiated with 650 krad gamma radiation. Even though the LNA is not specifically radiation-hardened, no degradation on its performance has been observed.