Noise limits of GaAs and InP microwave FETs determined by dynamic analysis

A dynamic one-dimensional analysis of electron transport from source to drain in GaAs and InP short-channel FETs is used to determine the effects of device cooling and channel length on both gain-bandwidth product and optimum noise figure of these devices. The analysis models intervalley scattering using a Monte Carlo calculation method. It is shown that both GaAs and InP FETs should exhibit excellent noise performance, virtually limited only by the values of such parasitic elements as source and drain resistances and feedback capacitances. InP is shown to be marginally superior to GaAs in terms of independence of optimum noise figure on channel field.