A crystaloscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystalof piezoelectricmaterial to create an electrical signal with aprecise frequency. This frequency is often used to keep track of time, asin quartz wristwatches, to provide a stable clocksignal for digital integratedcircuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used isthe quartz crystal, so oscillator circuits incorporating them becameknown as crystal oscillators,^[1] butother piezoelectric materials including polycrystalline ceramics are used insimilar circuits.

A crystal oscillator, particularly one made of quartz crystal, works by being distorted by an electric field when voltage is applied to an electrode near or on the crystal. This property is known as electrostriction or inverse piezoelectricity. When the field is removed,the quartz - which oscillates in a precise frequency - generates an electricfield as it returns to its previous shape, and this can generate a voltage. Theresult is that a quartz crystal behaves like an RLC circuit.

Quartz crystals are manufactured for frequencies from a few tensof kilohertz to hundreds of megahertz. More than two billion crystalsare manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cell phones.Quartz crystals are also found inside test and measurement equipment, such ascounters, signalgenerators, and oscilloscopes.