What is a crystal oscillator? Basic knowledge introduction

In every single-chip system, there is a component called a crystal oscillator. So, what is a crystal oscillator? How much do you know about crystal oscillators? This article will introduce it to you.

I. What is a crystal oscillator?

A crystal oscillator mainly refers to a crystal oscillator, and a crystal oscillator is a thin sheet cut from a quartz crystal according to a certain angular orientation. We simply call it a crystal chip, and it is the most important component in the clock circuit. The quartz crystal resonator, simply called quartz crystal or crystal, crystal oscillator; while the crystal element added inside the package to form an oscillation circuit is called a crystal oscillator.

II. What is the working principle of a crystal oscillator?

A crystal oscillator is mainly a resonant device made by utilizing the piezoelectric effect of a quartz crystal. If an electric field is applied to the two electrodes of the quartz crystal, the crystal chip will undergo mechanical deformation. Conversely, if mechanical pressure is applied to the two sides of the crystal chip, an electric field will be generated in the corresponding direction of the crystal chip, and this physical phenomenon is called the piezoelectric effect. If an alternating voltage is applied to the two poles of the crystal chip, the crystal chip will undergo mechanical vibration, and at the same time, the mechanical vibration of the crystal chip will generate an alternating electric field.

In general, the amplitude of the mechanical vibration of the crystal chip and the amplitude of the alternating electric field are very small. However, when the alternating voltage applied externally has a certain specific frequency, the amplitude significantly increases, much larger than that at other frequencies. This phenomenon is called piezoelectric resonance, which is very similar to the resonance phenomenon of an LC circuit. Its resonant frequency is related to the cutting method, geometric shape, and size of the crystal chip.

III. What are the functions of a crystal oscillator?

1. Provide basic clock signals: Usually, a system will share one crystal oscillator, mainly to facilitate each part to maintain synchronization. For example, some communication systems use different crystal oscillators for base frequency and radio frequency, and the frequency is adjusted electronically to ensure synchronization.

2. Provide the required clock frequency for the system: The crystal oscillator is usually used in conjunction with a phase-locked loop circuit to provide the required clock frequency for the system. If different subsystems require different frequencies of clock signals, different phase-locked loops connected to the same crystal oscillator can be used to provide them.