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 crude example is a typical inverting op-amp configuration with a light-dependent resistor (LDR) in the feedback loop. The gain of the amplifier then depends on the light falling on the LDR, that can be provided by an LED (an optocouple). The gain of the amplifier is then controllable by the current through the LED. This is similar to the circuits used in optical audio compressors.

A voltage-controlled amplifier can be realised by first creating a voltage-controlled resistor (VCR), which is used to set the amplifier gain. The VCR is one of the numerous interesting circuit elements that can be produced by using a JFET (junction field-effect transistor) with simple biasing. VCRs manufactured in this way can be obtained as discrete devices, e.g. VCR2N.

A further type of circuit uses operational transconductance amplifiers.