Large-signal circuit-based time domain analysis of high frequency devices including distributed effects

A fully distributed equivalent circuit model for MESFET is presented in this paper. The distributed circuit model incorporates sufficient number of segments to account for accurately wave propagation effects along device width. For the first time, distributed model having several segments is analyzed in time domain, which has the capability to evaluate large signal behavior. For a given MESFET, passive equivalent circuit elements are extracted from full wave simulation of the passive part as coplanar-coupled transmission lines using finite difference time domain technique. Active equivalent circuit elements are obtained from full hydrodynamic simulation with Curtice large signal model. The two equivalent circuits are combined together to form the basic unit segment. Several high frequency and high power characteristics of transistors are investigated and compared with previously published results.

I. Introduction

At high frequency when device dimension becomes comparable to wavelength, the wave propagation effect needs to be considered in device modeling. Full wave global modeling approach can be used to describe wave device interaction [1]. But full wave technique is time consuming and needs extensive computer memory. On the other hand distributed equivalent circuit model [2]–[4] can well accounts the wave propagation effect and it is very suitable for CAD applications.