Frequency dependence of source access resistance of heterojunction field-effect transistor

The source resistance of a heterojunction field-effect transistor (FET) has been investigated using classical methods and published zero drain-source impedance measurements. The channel configuration under the gate of the FET is described by a distributed RC dipole and expressed in terms of the intrinsic impedance parameters Z(ij). It is shown that the frequency dependence of the equivalent access resistance of the FET can be represented as a distributed circuit with equivalent resistance in the GaAlAs layer and the two-dimensional electron gas. The effect of source resistance on the noise factor is considered, and the influences of technological parameters on the structure of the FET is discussed. The frequency evolution of access resistance is given for different technological data.