What is a function generator

Function generator

When measurements are taken on electronic devices, predominantly on analog ones, it is often necessary to generate signals that serve as input signals for the device under test. This signal generation can be taken over by function generators.


A function generator is an electronic device that generates signals in various waveforms, frequencies, and amplitudes. The basic waveforms of function generators are the sine, the square and the triangle. Further waveforms such as the pulse and the sawtooth can be derived from these basic signal forms.

From a technical point of view, the heart of a function generator is a square wave generator. By integrating the output voltage, a triangular signal is generated and, through slow amplitude limitation using shaping, the sinusoidal signal is generated. The frequency range of function generators can be set in stages or continuously and ranges from ultra-low frequencies in the microhertz range (µHz) up to the double-digit megahertz range (MHz). The output voltage can also be set in steps or continuously, typically between a few millivolts (mV) and two-digit volts (V). In addition, function generators can generate single oscillations and bursts and can be triggered and wobbled.

There is of course a wide range of function generators that differ in a few important parameters. There are the signal forms. In addition to the basic signal forms mentioned, some function generators can also generate white noise, others also work as a DC voltage source and still others fulfill the functions of a modulator or wobbler.

Important criteria are the setting and accuracy of frequency and voltage, the duty cycle, the rise time, the overshoot, the signal symmetry and the pitch of the square wave signal, the duty cycle and the linearity of the triangular signal and the distortion factor of the sinusoidal signal. In the case of tunable function generators, the amplitude response over the tunable frequency range should also be mentioned. Since some function generators work with direct digital synthesis (DDS), they achieve accuracy values ​​of 10exp-6 and higher.

In addition to the function generators mentioned, there are also those that can generate any signal shape. These function generators are called arbitrary waveform generators or Arb function generators for short.