High-frequency MESFET noise modeling including distributed effects

A microwave field-effect transistor (FET) noise analysis is presented including distributed effects caused by the wave propagation along the width of the gate. Using this model the noise characteristics of submicron gate MESFETs at frequencies beyond 20 GHz are evaluated. It is ascertained that in the case of well-designed quarter-micron low-noise MESFETs, distributed effects may be neglected. Common lumped approximations, on the other hand, are shown to produce noticeable deviations. An improved lumped model is proposed. The analysis presented can also be used with high-electron-mobility transistor (HEMT) devices after introducing adequate geometry and small-signal parameters.<
>