- In application, where the high level of stability is required, crystal oscillators is the obvious choice.
- So not only this crystal provide high level stability, but it also provide good selectivity. Because the crystal which is used in this oscillator has a very high quality factor. Typically something like 10000 to 20000 and some crystals have an even higher quality factor.
- Because of these desired properties, these crystal oscillators are used in radio and telecommunications. As well as they are part of many digital circuit and they are used in smartphone and desktop computers for generating the stable clock frequency.
- Similarly they are essential part of the microcontrollers for generating the clock signals.
- So, this crystal can generate stable frequencies from 100s of kHz to even 100s of MHz.
Piezoelectric effect
So these crystal oscillator work on the principle of inverse piezo-electric effect and it is made up of piezo electric material. So whenever some external voltage is applied to certain materials then they produce the mechanical deformation. So suppose if apply the AC signal of particular frequency, then this material starts vibrating at the same frequency. And this effect is known as the piezoelectric effect.
Or in other end, whenever we apply the external force to this piezo-electric material, then they generate the voltage across the two terminals. If we mechanically force them to vibrate at the certain frequency, then they can generate the AC signal of the same frequency. And this effect is known as the piezoelectric effect. And the material which shows this effect is known as the piezoelectric material.
Rochelle salt, Quartz, and tourmaline are the few examples of naturally occurring which posses this piezoelectricity. Among these materials, the Rochelle salt has the maximum piezoelectric activity. That’s mean it generate maximum vibration in given applied voltage. But mechanically it is weakest and it can break very easily also were this tourmaline has a least piezoelectric activity but mechanically strong. Quartz is the come between the Rochelle salt and tourmaline as it give moderate piezoelectric activity and mechanical strength. Therefore it is widely used material.