Studies on small- and large-signal noise in solid-state amplifiers

The paper reports a summary of results concerning the study of noise in solid-state amplifiers, operating under smalland large-signal conditions. Starting from the standard Noise Figure (NF), we go through the effective NF which provides a measure of the white noise contribution as carrier power drives the amplifier into compression. This effective NF is derived from the white noise portion of AM and PM spectra around the carrier. Amplifier flicker noise contribution is also subject of the work. The effect of input and output matching conditions on the amplifier AM and PM noise, as well as on effective NF, has also been investigated and results are presented demonstrating that, under large-signal conditions, the amplifier AM, PM, and effective NF levels depend on input and output matching impedances. On the other hand, we discuss about the correlation between the degradation of noise performances, as the amplifier is driven into compression, with the evolution of the derivatives of the AM-AM and AM-PM conversion curves. Finally, the amplifier noise in presence of an interfering signal is also addressed.