Date of Award

Spring 1994

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical and Computer Engineering

First Advisor

Katz, Allen

Second Advisor

Whitman, Gerald Martin

Third Advisor

Niver, Edip

Abstract

A multi-dimensional model which accurately predicts device non-linearities over frequency and power has been developed for MESFETs used in a passive configuration in microwave signal processing applications.

Historically, MESFETs have been used in linear control applications as passive microwave switches and attenuators. More recently, MESFETs operated as passive elements have been employed as power-sensitive non-linear transfer function generators to produce limiters, phase shifters, and linearizers. These devices offer simplicity, high performance, and the opportunity for application in MMIC technology.

This thesis deals with a mapping of passive MESFET non-linear characteristics, and provides insight into the causes of non-linearity in MESFETs when operated as control elements at near zero drain voltage. Five unique operating modes are identified, and discussed in terms of their equivalent circuit models.

This work also deals with computer aided model extraction and non-linear simulation of MESFET characteristics, and presents a multi-dimensional lumped element model which accurately predicts device non-linearity over a wide range of power (-35 to > 10 dBm) and frequency (.1 to > 18 GHz). The application of this model to the design of a traveling wave tube amplifier (TWTA) linearizer is demonstrated. The model allows linearized TWTA transfer characteristics and two-tone carrier-to-intermodulation (C/I) performance to be predicted using standard CAD software.

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