Quartz itself is not able to produce frequency, but in the circuit, it can play its own effect, Xiaobian will analyze the reasons for you.



An electric field is applied to the two electrodes of the quartz crystal, and the corresponding wafer is mechanically deformed. If mechanical pressure is applied to both sides of the wafer, an electric field will be generated in the corresponding direction of the wafer, which is the piezoelectric effect. If an alternating voltage is applied to the two poles of the wafer, the wafer will vibrate accordingly, and the mechanical vibration of the wafer will result in an alternating electric field. Usually the amplitude of the mechanical vibration of the wafer and the amplitude of the alternating electric field are relatively small, but when the frequency of the external alternating voltage is a certain value, the amplitude will be increased, thus forming a piezoelectric resonance, which is very similar to the resonance phenomenon of the LC circuit.



Crystal oscillator in the circuit can be equivalent to a capacitor and a resistor in parallel and then series a capacitor two-terminal network, usually this network has two resonance points, in the frequency of high and low points, the lower frequency is a series resonance, the higher frequency is a parallel resonance. The crystal itself has certain characteristics, resulting in the distance between the two frequencies is relatively close, in a certain frequency range, the crystal oscillator can be called an inductor, so as long as the two ends of the crystal oscillator in parallel on the appropriate capacitance it will form a parallel resonant circuit.