ceramic resonator circuit
Ceramic resonators are made of high-stability piezoelectric ceramics, generally lead zirconium titanate (PZT) which functions as a mechanical resonator. When voltage is applied, its piezoelectric "vibration behavior" causes an oscillating signal. The thickness of the ceramic substrate determines the resonance frequency of the device.
A ceramic resonator is often used in place of quartz crystals as a reference clock or signal generator in electronic circuitry because of its lower cost and smaller size. It is used on circuits where frequency specifications aren't highly critical (quartz has a 0.001% frequency tolerance, while PZT has a 0.5% tolerance).