CRYSTAL OSCILLATOR THEORY

figure shows Circuit diagram Of Crystal Oscillator

It is a type of Oscillator in which the usual electrical Resonating circuit is replaced by a mechanical vibrating crystal.

It is used whenever,High stability is required under High frequency.
The crystal oscillator having the main advantage that, it produce stable output even in high frequency of operation.

The crystal commonly used as a tank Circuit for an Oscillator is QUARTZ.

The operational frequency of the crystal is determined by the way in which it is cut.

Quartz exhibits an important property, PEIZO ELECTRIC EFFECT.

Peizo Electric Effect is a phenomenon by which,

If we are applying a mechanical stress to the surface of a crystal it produces an output voltage

Corresponding to the stress applied to it.
Conversely, if we applying a voltage across the surface of crystal, it will distorted by an amount equal to the applied voltage.


This property is used in crystal oscillators, that a sinusoidally varing input voltage is applied to the crystal it will vibrate at a frequency equal to the input voltage. This makes the Tank circuit Resonating.