Function Generator

Function generators are a form of signal generator that can generate waveforms with common shapes: sine, square, pulse, triangular, sawtooth, etc . . .

Function Generators includes:
Function generator     Types of function generator     Function generator specs    

Signal generator types:     Signal Generator Basics     RF signal generator basics     Arbitrary waveform generator    

A function generator is a specific form of signal generator that is able to generate waveforms with common shapes. Unlike RF generators and some others that only create sine waves, the function generator is able to create repetitive waveforms with a number of common shapes.

Typically a function generator may be able to vary the characteristics of the waveforms, changing the length of the pulse, i.e. the mark space ratio, or the ramps of the different edges of a sawtooth waveform, but it will only be able to create the waveforms that are built in to the function generator.

Another capability is that the function generator may be able to add a DC offset to the signal.

Typically function generators are only able to operate at relatively low frequencies, some only operating to frequencies of around 100kHz, although more costly models can operate at higher frequencies, up to 20 or 30MHz. Despite this the need for function generators is often, but not always in the lower frequency end of the frequency spectrum.

Typical function generator form of signal generator

Function generator capabilities

Function generators are capable of producing a variety of repetitive waveforms, generally from the list below:

  • Sine wave:   A function generator will normally have the capability to produce a standard sine wave output. This is the standard waveform that oscillates between two levels with a standard sinusoidal shape.

    Sine wave signal as synthesized in a function generator
  • Square wave:   A square wave is normally relatively easy for a function generator to produce. It consists of a signal moving directly between high and low levels.

    Square wave signal as synthesized in a function generator
  • Pulse:   A pulse waveform is another type that can be produced by a function generator. It is effectively the same as a square wave, but with the mark space ratio very different to 1:1.

    Pulsed wave signal as synthesized in a function generator
  • Triangular wave:   This form of signal produced by the function generator linearly moves between a high and low point.

    Triangular wave signal as synthesized in a function generator
  • Sawtooth wave:   Again, this is a triangular waveform, but with the rise edge of the waveform faster or slower than the fall, making a form of shape similar to a sawtooth.

    Sawtooth wave signal as synthesized in a function generator

Function generator controls

In addition to a selection of the basic waveforms that are available, other controls on the function generator may include:

  • Frequency:   As would be expected, this control alters the basic frequency at which the waveform repeats. It is independent of the waveform type.
  • Waveform type :   This enables the different basic waveform types to be selected:
    • Sine wave
    • Square wave
    • Triangular wave
  • DC offset:   This alters the average voltage of a signal relative to 0V or ground.
  • Duty cycle:   This control on the function generator changes the ratio of high voltage to low voltage time in a square wave signal, i.e. changing the waveform from a square wave with a 1:1 duty cycle to a pulse waveform, or a triangular waveform with equal rise and fall times to a sawtooth.

Function generators are normally very easy to operate. With modern processing technology often included this gives the possibility of many additional features including ease of operation, and remote control via one or more of the many standards available.

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