What type of semiconductor device is designed for use as a voltage-controlled capacitor?

Explicación

The depletion region of a reverse-biased junction acts as the dielectric of a capacitor, and its width — and therefore the capacitance — changes with the applied reverse voltage; a varactor is a diode optimized for that behavior and is used to tune oscillators and filters electrically. A tunnel diode is a negative-resistance device, an SCR is a switch, and a Zener is a voltage reference.