The role of crystal oscillator, the role of crystal oscillator circuit

1. General-purpose crystal oscillator, used in various circuits, to generate oscillation frequency.

2. Quartz crystal resonator for clock pulse is used to generate standard pulse signals with other components, which is widely used in digital circuits.

3. Quartz crystal resonator for microprocessor.

4. Quartz crystal resonator for CTVVTR.

5. Quartz crystal oscillator for clocks and watches.

Crystal oscillatorThe role is to provide the basic clock signal for the system. Often, a system shares a single crystal oscillator, making it easy for all parts to stay in sync. Some communication systems use different crystal oscillators for their fundamental frequency and radio frequency, which are kept synchronized by electronically adjusting the frequency.

Crystal oscillator, the whole process is called crystal **, in the single-chip microcomputer.

The role of the crystal oscillator in the system is very large, it combines the internal circuit of the single-chip microcomputer to generate the necessary clock frequency of the single-chip microcomputer.

The execution of all instructions of the single-chip microcomputer is based on this, the higher the clock frequency provided by the crystal oscillator, the faster the running speed of the single-chip microcomputer.

How it works Crystal oscillators have a piezoelectric effect.

That is, the crystal will be deformed after the voltage is applied to the two poles of the wafer, and if the external force deforms the wafer, the metal sheet on the two poles will generate voltage. If an appropriate alternating voltage is applied to the wafer, the wafer will resonate (the resonant frequency is related to the inclination angle of the quartz bevel, etc., and the frequency is constant).

Crystal oscillators use a type of energy that combines electrical and mechanical energy.

Interconverted crystals that operate in a resonant state can provide stable, accurate single-frequency oscillations. Under normal operating conditions, the absolute accuracy of ordinary crystal frequency can reach 50 parts per million. Taking advantage of this feature, the crystal oscillator can provide relatively stable pulses, which are widely used in the clock circuit of microchips.

The wafers are mostly quartz semiconductor materials.

The housing is encapsulated in metal.

1.Crystal oscillator function: provide a stable clock signal for the normal operation of the single-chip microcomputer.

Principle: If an electric field is added to the two plates of the quartz crystal, the wafer will produce mechanical deformation, and the mechanical force applied to the plate will deform it, and the corresponding charge will be generated on the plate, which is called the piezoelectric effect. If an alternating voltage is applied to two plates, the wafer will be mechanically deformed**, and this machinery** will also produce an alternating electric field (relatively small), but when the frequency of the applied alternating voltage is equal to the intrinsic frequency of the wafer (determined by its shape and size), the amplitude of the mechanical vibration will intensify and the alternating electric field will be increased.

It's called piezoelectric harmonics.

2.Even if the crystal oscillator is removed, the circuit can still oscillate, and if you change the two capacitors to adjustable capacitors, you can get a certain frequency you want, so what else does the crystal oscillator do: crystal oscillator, ceramic resonant groove, RC oscillator and silicon oscillator are the four clock sources suitable for microcontrollers.

Optimizing a clock source design for a specific application relies on the following factors: cost, accuracy, and environmental parameters. RC oscillators are quick to start up and low cost, but are typically inaccurate over the entire temperature and operating supply voltage range, varying from 5% to 50% of the nominal output frequency; However, oscillators based on crystal and ceramic resonant grooves typically provide very high initial accuracy and low temperature coefficients compared to RC oscillators.

The crystal oscillator is used to produce a fixed oscillation frequency, the full name is the crystal oscillator, which provides a clock signal for the CPU, the higher the frequency of the crystal oscillator, the faster the CPU runs, and the CPU cannot run without the crystal oscillator, its role is equivalent to the human heart, which cannot be missing! Without the crystal oscillator, the system would not work.

Crystal oscillatorIt can be a "crystal resonator" or a "crystal oscillator".

There are two kinds of functions.

Provide system oscillation pulse, stabilize frequency, select frequency,

The role of the crystal circuit is to provide the basic clock signal to the system. Usually a system shares a crystal oscillator, which is convenient for all parts to keep in sync, and some communication systems use different crystal oscillators for the fundamental frequency and radio frequency, and the frequency is electronically adjusted to keep them synchronized.

The crystal oscillator is used in conjunction with a phase-locked loop circuit to provide the clock frequency required by the system. If different subsystems require clock signals of different frequencies, they can be provided with different phase-locked loops connected to the same crystal oscillator.

How it works

Electrically, it can be equivalent to a two-terminal network of capacitors and a resistor connected in parallel and a capacitor in series. Electrically, this network has two resonance points, which are divided into high and low frequencies, where the lower frequency is series resonance and the higher frequency is parallel resonance.

Due to the characteristics of the crystal itself, the distance between these two frequencies is quite close, in this extremely narrow frequency range, the crystal oscillator is equivalent to an inductance, so as long as the two ends of the crystal oscillator are connected in parallel with a suitable capacitor, it will form a parallel resonant circuit.

This parallel resonant circuit can be added to a negative feedback circuit to form a sine wave oscillation circuit, because the frequency range of the crystal oscillator equivalent to the inductance is very narrow, so even if the parameters of other components change greatly, the frequency of this oscillator will not change greatly.