Ultra-low-noise cooled microwave PHEMT amplifiers for radio astronomy applications

The main aim of this work was to design octave-band amplifiers on commercially available transistors over the frequency range from 0.5 to 4 GHz with emphasis on noise and stability performances at cryogenic temperatures. The major area of application for such devices is microwave and mm-wave high-sensitive receivers, where these ones are usable either as input or IF amplifiers. Performance obtained is the best among devices on commercially available transistors. When incorporated in radioastronomy superheterodyne receivers as IF-amplifiers, they have largely determined implementation of record characteristics of high-sensitive mm-wave receiving systems.