PROPAGATION EFFECTS ON Z PARAMETERS IN AN FET EQUIVALENT CIRCUIT

Abstract

The design of microwave circuits needs a good analysis of the performances of the field-effect transistor equivalent circuit. Indeed the small signal equivalent circuit of the field-effect transistors makes it possible to easily determine their performances such as the gain and the noise figure. A field-effect transistor constitutes a propagation structure along its gate width. Telegraphists’ equations are solved for this structure. One deduces from this the effect of the propagation on the transistor Z-parameters which can be taken into account in electric simulations and which may improve the use of long transistors at lower frequencies and of short transistors at higher frequencies.