Variable-gain amplifier

A voltage-controlled amplifier (English for voltage controlled amplifier ), short VCA is an electronic amplifier whose gain can be controlled by a control voltage. Core component is the Gilbert cell.

The same function can also have an algorithm in a digital audio system. The gain of a variable gain can be set to a voltage other than by an electrical current, or a digital output value.


  • In the electronic music VCAs are widely used in compressors ( Compressor ), limiters, gates and many other effects and electronic musical instruments. Mostly these are electronic components, such as those manufactured by other companies, such as dbx, or THAT Analog Devices. The term amplifier is somewhat misleading, since the input signal is lowered or maximum looped through unchanged, which corresponds to a " gain" by a factor of 1. Therefore VCAs are also sometimes referred to as Voltage Controlled Attenuators.
  • In the consumer electronics and radio VCAs are used for automatic uniform Auspegelung of signals or suppressing the background noise. Some of these applications are similar to those of electronic music; although used recently, especially in the professional field, much higher quality Pegelungsverfahren and components; see also squelch, squelch or gate.