Study of flicker phase modulation and amplitude modulation noise in field effect transistor amplifiers

We present theoretical and experimental results on up-conversion of 1/f low-frequency noise into amplitude modulation (AM) noise and phase modulation (PM) noise in linear field-effect transistor (FET) amplifiers. Two types of transistors, used in a common source (CS) configuration, were studied: junction field-effect transistors (JFETs) and metal-semiconductor field-effect transistors (MESFETs). AM and PM sensitivities to baseband current and voltage noise are computed from theory and experimentally measured. A negative feedback technique that reduces the baseband noise is also investigated.