Noise-Parameter Measurements of Very-Low-Noise Amplifiers at Ambient and Cryogenic Temperatures

Radio-telescope receivers are developed to sense very weak astronomical signals. The sensitivity of a radio telescope is inversely proportional to its noise temperature, which is largely dependent on the amount of noise generated in the receiver low-noise amplifier (LNA). In addition, a radio telescope sensitivity is also proportional to its collecting area; however, it is very costly to enhance sensitivity by increasing the collecting area. Given the high costs associated with increasing the collecting area, the development of methods of reducing LNA noise becomes critical to optimizing the operation of radio telescopes. Such LNA-noise reduction techniques must first be verified via laboratory measurements and then subsequently verified using field measurements on the telescope.