Cryogenic Broadband Ultra-Low-Noise MMIC LNAs for Radio Astronomy Applications

0.5-13- and 24-40-GHz broadband cryogenic monolithic-microwave integrated-circuit low-noise amplifiers (LNAs) have been designed and fabricated using a 130-nm InP HEMT process. Packaged LNAs have been measured at both 300 and 15 K. At 300 K, the measured minimum noise temperature of the 0.5-13-GHz LNA was 48 K at 7 GHz with a gain between 34-40 dB. At 15 K, the measured minimum noise temperature was 3 K at 7 GHz and below 7 K within the entire 0.5-13-GHz band with a gain between 38-44 dB. The 24-40-GHz LNA exhibited a lowest noise temperature of 110 K and an average of 125 K with a gain of more than 27.5 dB at 300 K. When cooled down to 15 K, the noise temperature dropped to a minimum of 10 K and average of 13.2 K with a gain of 28 dB. The results are of large interest for radio astronomy applications where large bandwidth and low noise figure in the receivers are key figures in the system design.