What Is a Function Generator?

A function generator is a test equipment for electronic or electrical devices. It ranges in size from half a shoebox to the size of several shoeboxes. While plugged in to power from the electric power outlet or energized from batteries, a function generator produces either repeating electrical signal or a one-shot electrical signal. The output signal from a function generator, usually a repeating electrical signal also known as periodic signal, can be generated by the electronic components or in combination with software. A function generator may provide several typical waveforms, which include the sine, square, triangular, and sawtooth waves.

Sine waves are naturally occurring waveform outputs of electrical power generators that supply home electricity, and these waves can be imagined as smoothly rising, dropping, and reversing waveforms. Square waves remain in one of two states most of the time. For instance, a square wave may periodically shift between “plus” 1 volt (V) and “minus” 1 V. Triangular and sawtooth waves similarly rise or ramp up. Unlike triangular waveforms, which drop slowly, sawtooth waveforms drop rapidly.

The output of function generators is usually connected to a device under test or study. For instance, the performance of a public address system (PAS) can be measured by injecting an audio signal into the PAS input and then measuring levels of signal and distortion at the output. A function generator that generates a sine wave is used for this purpose.

Common parameters of a function generator are frequency and output level. Frequency is the cycle per second of the wave output. For example, if a function generator produces a sine wave that repeats 1,000 times per second, it is referred to as 1,000 cycles per second or 1,000 Hertz (Hz). Output level is typically in electrical volts or electrical power in watts (W) or milliwatts (mW). Some special purpose function generators indicate output level in decibel relative to 1/1,000 W (dBm).

Function generators are used for the testing, troubleshooting, and quality assurance of products and systems in many industries, such as broadcast, telecommunications, manufacturing, research, and energy production. Sophisticated function generators have very accurate frequency references and level settings. Special purpose function generators are available for special testing needs. A television (TV) test pattern generator, for example, is a function generator designed to make sure that the major circuitry of a TV set is working even before it receives a standard TV signal. Other special purpose function generators are used by various industries in sites and laboratories worldwide.