TABLE OF CONTENTS The superior physical properties of gallium arsenide over those of silicon have led researchers worldwide to use the material as a semiconducting and semi-insulating substrate for both high frequency analog and high-speed digital integrated circuits. Much activity is now concentrating on the ability to integrate large numbers of FETs into chip areas of less than 4 mm 2 to perform sophisticated functions such as code generation and random access memories at speeds of up to 4 GBits/sec. Analogue ICs which contain complete receiver front-ends, phase and amplitude coded transmitters, analogue to digital converters and synthesizers, for example, are presently being developed following the encouraging results produced during the last five years with single function circuits such as low-noise amplifiers and oscillators.
In parallel with the utilization of both silicon IC circuit techniques at the lower frequencies (i.e. up to approximately 4 GHz) and the ingenious use of FETs in circuits up to 35 GHz or so, sophisticated technologies are emerging to cope with the demands of the circuit designers.
This chapter is divided into four main sections. The first section deals with the philosophy behind and design approaches of analogue circuits. This is followed by an equivalent account for digital GaAs ICs. A review is presented of the various approaches and technologies that have been developed including the use of ion implantation and planar IC processing. A considerable number of circuit examples are included to indicate to the reader the range of activities being pursued in this...
