A function generator is a piece of electronic test equipment or software used to generate different types of electrical waveforms over a wide range of frequencies. These waveforms can be either repetitive or single-shot, in which case some kind of triggering source is required (internal or external). Usually a function generator produces waveform that is produced by the repetitive charging and discharging of the capacitor to which a constant energy source is connected.
One of the most useful features of the function generator is that it can be phase locked to an external signal source or another function generator. Other important features of the function generator are continuous tuning over wide bands with max-min frequency ratios of 10 or more, wide range of frequencies from a few Hz to MHz, flat output amplitude and modulation capabilities like frequency sweeping, frequency modulation and amplitude modulation.
Function Generators are used in development, testing and repair of electronic equipment, e.g. as a signal source to test amplifiers, or to introduce an error signal into a control loop. Some of the most common waveforms produced by the function generator are the sine, square, triangular and saw tooth waveforms.