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What is a crystal oscillator

:2022-08-12 :ICKU

Crystal oscillator is a crystal [trade_no](quartz) piezoelectric effect that causes oscillation accuracy by using high frequency when using one of the passive components. Sometimes abbreviated as XTAL. Quartz watches, wireless communications, computers and other essential components of modern electronic equipment.


Some electronic devices require AC signals with highly stable frequency, while LC oscillators are less stable and prone to frequency drift (that is, the frequency of the generated AC signal is easy to change). Using a special element quartz crystal in the oscillator can produce a highly stable signal. This kind of quartz crystal oscillator [trade_no]is also called crystal oscillator.



Cut a slice on the quartz crystal according to a certain direction, Polish both ends of the slice and coat it with a conductive silver layer, and then connect two electrodes from the silver layer and package it. The component formed in this way is called quartz crystal resonator, which is called quartz crystal for short.


Quartz crystal has two resonant frequencies, FS and FP, FP is slightly larger than FS. When the frequency of the signal added to both ends of the quartz crystal is different, it will show different characteristics.


The crystal oscillator has piezoelectric effect, that is, the crystal will deform after applying voltage at the two poles of the chip. On the contrary, if the chip is deformed by external force, the metal sheet on the two poles will generate voltage. If an appropriate alternating voltage is applied to the wafer, the wafer will produce resonance (the resonance frequency is related to the inclination angle of the quartz slope, and the frequency is certain).


Crystal oscillator uses a kind of crystal that can transform electrical energy and mechanical energy into each other. It can provide stable and accurate single frequency oscillation when it works in resonance state. Under normal working conditions, the absolute accuracy of ordinary crystal oscillator frequency can reach 50 parts per million. Using this characteristic, the crystal oscillator can provide relatively stable pulses, which is widely used in the clock circuit of microchips. The wafer is mostly made of quartz semiconductor material, and the shell is sealed with metal.