The Noise Temperature Analysis on a Space‐Grade Cryogenic Low Noise Amplifier Using Two Measurement Methods

Abstract The noise of a cryogenic low‐noise amplifier (cryo‐LNA) directly impacts the sensitivity of a terahertz superconducting heterodyne receiver. This paper aims to evaluate the noise temperature of a cryo‐LNA and its suitability as the first stage IF amplifier for the heterodyne receiver, specifically the high‐sensitivity terahertz detection module for the China Space Station Survey Telescope. Both the Cold Attenuator (CA) Method and the Variable Temperature Load (VTL) Method are employed to ensure confidence in the measured values. The maximum difference in results is 1K within the frequency range of 0.1–2 GHz, contributing to an uncertainty of 4K in the receiver's noise temperature. The measurement accuracy of the noise temperature is analyzed in detail, with particular emphasis on the influence of the cryogenic attenuator and the noise contribution from the connecting cable with a temperature gradient. Additionally, the dependence of the cryo‐LNA's noise temperature on physical temperature and radiation hardness are verified to assess suitability for space applications.