Studies on AM and PM noise in microwave amplifiers working under linear and non-linear operating conditions

A summary of results is reported concerning the study of noise in solid-state amplifiers operated under small- and large-signal conditions. Amplitude (AM) and phase (PM) noise spectra, including flicker and white amplifier noise contributions, are measured using heterodyne techniques. An effective NF is also derived from the amplifier white noise portion of AM and PM spectra around the carrier, as carrier power drives the amplifier into compression. Specific setting and calibration procedures of the AM and PM noise measurement setups are discussed. Different measurement results are reported illustrating the dependence of flicker and white AM and PM noise with carrier power, the role of matching conditions and the effect of an interference signal on amplifier carrier noise.