Design, realisation and test of GaAs-based monolithic integrated X-band high-power amplifiers

Abstract

A phased-array antenna can consist of a few to several thousands of TR modules [1.1].This large amount of TR modules requires the use of cheap highly integrated components to make the realisation of phased-array antennas economically feasible.The use of Monolithic Microwave Integrated Circuits (MMIC) is of vital importance for the realisation of this objective.In figure 1.2, the nowadays most commonly used components in a TR module are shown.The indicated phase shifter () and amplitude regulator (ATT) control the direction and the shape of the antenna pattern.The output power required to achieve a specified detection range is generated with the help of the depicted high-power amplifier (HPA).In the receive channel a low noise amplifier (LNA) is used to amplify the incoming radar signal.The TR module depicted in figure 1.2, shows the situation commonly encountered at the start of the work in 1992.The TR module topology foreseen for the near future is shown in figure 1.3.Most of the functions are integrated into one multi-function chip (MFC).Examples of such multi-function chips are described in literature [1.2, 1.3].Probably the LNA and limiter will be integrated into one single chip. Problem, goal and organisation Problem and goalThe design of integrated microwave high-power amplifiers at X-band (8.0 -12.4 GHz), that have both a broad bandwidth and a high efficiency, is the problem investigated in this thesis.These high-power amplifiers will be realised on GaAs wafers in two different transistor technologies, namely a MEtal Semiconductor Field Effect Transistor (MESFET) technology and a pseudomorphic Heterojunction Field Effect Transistor (HFET) technology.At the start of the work described in this thesis: No procedure for the design of microwave integrated high-power amplifiers was available. No models for the transistors were available. The models for the passive components were inaccurate or even unavailable. No measurement systems were available for both the characterisation of high-power amplifiers and active and passive components including transistors, capacitors etc.The primary goal pursued in this thesis therefore is, to give a systematic overview of all design steps that are necessary to realise a successful wideband high-efficiency microwave high-power amplifier.In addition, the component models and the measurement methods, developed in the scope of this thesis, which form an integral part of the design Components 15 Components 2.1 IntroductionTo choose for the right technology is of vital importance for obtaining a good high-power amplifier performance.In this thesis, technology will be used interchangeably with process.The term technology covers the substrate material, the