A SMALL-SIGNAL HIGH FREQUENCY EQUIVALENT OIRCUIT FOR THE FIELD-EFFECT TRANSISTOR

Abstract

The field effect transistor is considered as an active, distributed non-uni.form transmission line and a differential equation for the small-signal a.c. case is derived. The short-circuit admittance parameters of the device are determined from the solution of the differential equation. A high frequency equivalent circuit for the intrinsic device is then obtained from the first-order approximation of the analysis and the expressions for the elements of this circuit are derived for both the saturated and the non-saturated conditions. The normalized values of these elements are computed as functions of the gate and drain bias voltages and the results of these computations are presented graphically.