A Noise-Temperature Measurement System Using a Cryogenic Attenuator

Accurate and rapid noise-temperature measurements are critical to the modeling and development of high electron mobility transistor (HEMT) cryogenically cooled amplifiers. Four different techniques have been used in the laboratory to make noise-temperature measurements of cryogenically cooled amplifiers, and each of these is described below. Following this, the cryogenic pad method, the method most often used by the Cryogenics–Electronics Front-End Equipment Group at JPL, is described. Although the cryogenic pad and noise-figure meter are not in and of themselves new, combining them provides an elegant, simple, and quick solution to equivalent input noise-temperature and gain measurements.