Gain (electronics)

In electronics, gain is the ratio of signal output from a system to signal input to the system. Signal is usually measured in units of power, since a power gain is considered more meaningful than a voltage gain.

The ratio is often expressed in decibels (dB).

For example, if output=500mW and input=5mW then

gain=500/5 = 100 = 2Bel or 20dB