A voltage-controlled amplifier is an electronic amplifier that varies its gain depending on a control voltage (often abbreviated CV).
They have many applications, including audio level compression, synthesizers, and amplitude modulation.
A very simple example is a typical inverting op-amp configuration with an optocoupled light-dependent resistor in the feedback loop. The gain of the amplifier then depends on the light hitting the resistor, which is provided by an LED. This is the type of circuit used in "optical" audio compressors.
External links
