Balanced: Encyclopedia - Balanced

Balanced

See also balance, equilibrium.

In electronics, a balanced signal is one that is expressed as the difference between two conductors, as opposed to an unbalanced signal that is expressed as the difference between one conductor and a reference earth.

Low voltage differential signaling, twin-lead and standard low-impedance microphone cables are all examples of balanced signals. In all three of these applications, noise in a cable run is reduced by the fact that most of the noise is picked up equally by both conductors, and so the signal expressed as the difference between them is unaffected, with the noise cancelling out.

A push-pull amplifier stage is another example of a balanced circuit. In the traditional push-pull power amplifier circuit, the unbalanced signal is converted to balanced by a phase-splitter stage between the driver and power stages. The balanced signal may then be converted back to unbalanced by an output transformer (common in valve amplifiers) or may be used directly (common in transistor amplifiers).

A device that converts a balanced signal to unbalanced or vice versa is known as a balun.

Adapted from the Wikipedia article "Balanced", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki