Line driver

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In telecommunication, a line driver is an amplifier used to improve the transmission reliability of a usually digital intrafacility metallic transmission line, over extended distances, by driving the input to the transmission line with a higher than normal signal level.

An example of a line driver is an amplifier used to extend the range of an RS-232C digital signal beyond 50 feet (~15 m) while maintaining a specified bit-error ratio.

In Mobile Audio, a line driver is a small amplifier used to bolster the strength of the audio signal coming from the source unit.

The newly strengthened signal is then fed to its appropriate amplifier.

Gain on an amplifier needs to be set with regard to the input voltage the amplifier sees - the lower the input voltage, the greater the gain to produce a given loudness. When amplifying a very low-voltage signal, the noise-floor of the system raises, meaning that the amplifier is not only amplifying the low-voltage audio signal, but also the low-voltage noises picked up in the line along the way. By using a line driver, the amplifier's gains need not be set so high, thereby amplifying the audio signal with less of the low-level noise.

This can be useful especially in long runs of signal cable, which are more prone to picking up noise.