Cryogenic low-noise amplifiers of low power dissipation for space terahertz astronomy

Cryogenic low-noise amplifiers (CLNAs) are of particular interest for applications such as radio astronomy and quantum information science. Here we report on the design and characterization of low-power-dissipation wideband CLNAs for a terahertz spectrometer onboard China’s Space Station Telescope (CSST). A simple small-signal and noise model is established based on the DC and RF characteristics of SiGe heterojunction-bipolar-transistors (HBTs) adopted for this development. The developed SiGe HBT CLNAs at 4 K demonstrate an average noise temperature of 4.5 K and a gain of exceeding 35 dB in the frequency range of 0.1 GHz–1.1 GHz. With the power dissipation as low as 3 mW, the average noise temperature is still as low as 6.8 K. The combination of low power dissipation and low noise temperature is rather beneficial to applications in space instruments and complex systems.