Noise Measurements for Microwave Electron Device Characterization and Modelling Under Non-Linear Operating Conditions

The experimental procedures and laboratory set-ups aimed at the characterisation and empirical modelling of noise phenomena in microwave electron devices classically involve noise measurement under quiescent or small-signal transistor operation. However, low-noise circuit applications increasingly demand a deeper investigation also on the noise frequency conversion and modulation mechanisms, which arise in the presence of large-signal, non-linear operation of the device. In this talk, the inherent limitations of noise characterization carried out under linear operating conditions will be discussed, and some practical solutions will be described, for the experimental characterization of both LF noise (i.e., flicker, G-R) and RF noise (i.e., diffusion) in autonomous (oscillators) and forced (mixers, amplifiers) large-signal operation. These measurement set-ups are not only capable of assessing the device noise performance in non-linear regime, but they also provide essential information for the extraction of the cyclostationary equivalent sources defined by recently proposed non-linear empirical noise modelling approaches.