What Is a Varactor?
A varactor, or variable capacitance diode, is a type of semiconductor that changes its capacitance as the voltage applied to it is varied. Unlike standard diodes that primarily facilitate current flow in one direction, varactors are designed to store and manage charge.
The operation of a varactor revolves around its pn junction—a boundary between two types of semiconductor materials, p-type and n-type. Applying a reverse voltage across this junction expands the depletion zone, an area devoid of free charge carriers, effectively increasing the diode’s capacitance.
This unique capability to adjust capacitance through voltage makes varactors invaluable in electronics, particularly in frequency modulation and tuning circuits where precise control over capacitance is required to regulate oscillation frequencies.