Introduction

Waveform generators make up a group of instruments which are essential to the electronic circuit designer. At the simplest level, the sine wave, square wave and triangle waveform generator, covering the frequency range from a few hertz to several megahertz, is used to measure the gain and frequency response of amplifier circuits, and as a basic timing or input signal to the kind of experimental circuits that have been discussed so far in this book. Pulse generators are also of great value for circuit testing, providing both positive and negative going pulses with very fast rise and fall times, together with the facility of a separate trigger pulse from the instrument which precedes the main output pulse by some time which may be varied. A recent book by Chiang [1] covers many of these classical topics in detail and also deals with quite advanced instrumentation and signal processing techniques that rely heavily upon waveform generation.

In recent years, laboratory instruments using digital techniques for very complex waveform generation have been introduced. In these instruments, a microprocessor is used to generate the required waveform as a continuously changing digital output of eight, or more, bits, and this digital output is then converted into the required analog output by a digital to analog converter (DAC).