1. Crystal Oscillator Circuit and Its Working

2. Crystal Oscillator Circuit and Working
Introduction:
A crystal oscillator is an electronic oscillator circuit which is used for the mechanical resonance of a vibrating crystal of piezoelectric material. It will create an electrical signal with a given frequency. This frequency is commonly used to keep track of time. Crystal oscillators must be designed to provide a load capacitance.

3. Crystal Oscillator Circuit and Working
Different Types of Oscillator
Linear oscillators – Hartley oscillator, Phase-shift oscillator, Armstrong oscillator, Clapp oscillator, Colpitts oscillator.
Relaxation oscillators – Royer oscillator, Ring oscillator, Multivibrator Oscillator and Voltage Controlled Oscillator (VCO).

4. Crystal Oscillator Circuit and Working
What is a Quartz Crystal?
A quartz crystal exhibits a very important property known as the piezoelectric effect.
When a mechanical pressure is applied across the faces of the crystal.
A voltage which is proportional to mechanical pressure appears across the crystal.
That voltage causes distortion in the crystal.

5. Crystal Oscillator Circuit and Working
What is a Quartz Crystal?
Distorted amount will be proportional to the applied voltage.
An alternate voltage applied to a crystal it causes to vibrate at its natural frequency.
Quartz crystal in an electronic oscillator that consists of resistor, inductor, and capacitors.

6. Crystal Oscillator Circuit and Working
Quartz Crystal Circuit

7. Crystal Oscillator Circuit and Working
Crystal Oscillator Circuit Diagram

8. Crystal Oscillator Circuit and Working
Crystal Oscillator Circuit Diagram
Bipolar transistors or FETs are used in construction of Crystal oscillator circuits.
Because operational amplifiers can be used in different low frequency oscillator circuit.
It is below 100KHz but operational amplifiers do not have the bandwidth to operate.
It will be a problem at the higher frequencies that are matched to crystals which are above 1MHz.

9. Crystal Oscillator Circuit and Working
Crystal Oscillator Circuit Diagram
To overcome this problem Colpitts crystal oscillator is designed.
It will work at higher Frequencies.
In this Oscillator, the LC tank circuit that provides the feedback oscillations has been replaced by a quartz crystal.
Crystal Oscillators, that works with 16MHz frequency.

10. Crystal Oscillator Circuit and Working
Crystal Oscillator Working
Crystal oscillator circuit usually works on the principle of the inverse piezoelectric effect.
The applied electric field will produce a mechanical deformation across some materials.
It utilizes the vibrating crystal’s mechanical resonance.
It is made with a piezoelectric material for generating an electrical signal of a particular frequency.
Quartz crystal oscillators are highly stable.

11. Crystal Oscillator Circuit and Working
Crystal Oscillator Working
They consists of good quality factor(Q), they are small in size, and are economically related.
Quartz crystal oscillator circuits are more superior compared to other resonators like LC circuits, turning forks.
Generally in Microprocessors and Micro controllers we are using an 8MHz crystal oscillator.
The equivalent electrical circuit is also describes the crystal action of the crystal.

12. Crystal Oscillator Circuit and Working
Crystal Oscillator Working
The basic components used in the circuit are....
Inductance L represents crystal mass
Capacitance C2 represents compliance.
C1 is used to represent the capacitance that is formed because of crystal’s mechanical moulding.
Resistance R represents the crystal’s internal structure friction.
The quartz crystal oscillator circuit diagram consists of two resonances such as series and parallel resonance.

13. Crystal Oscillator Circuit and Working
Crystal Oscillator Working

14. Crystal Oscillator Circuit and Working
Crystal Oscillator Working
The series resonance occurs when the reactance produced by capacitance C1is equal and opposite to the reactance produced by inductance L.
The fr and fp represents series and parallel resonant frequencies respectively.
The values of ‘fr’ and ‘fp’ can be determined by using the following equations.

15. Crystal Oscillator Circuit and Working
Uses of Crystal Oscillator
In the design of microprocessors and microcontrollers, crystal oscillators are used for the sake of providing the clock signals.
In microcontroller an external crystal oscillator circuit will work with 12MHz that is essential.
This particular crystal oscillator which is having cycle rate at 1MHz to 3.33MHz is used to generate clock pulses.
It is required for the synchronization of all the internal operations.

16. Crystal Oscillator Circuit and Working
Application of Crystal Oscillator
There are various applications for crystal oscillator in various fields and some of crystal oscillator applications are given below.
Colpitts Crystal Oscillator Application
Applications of Armstrong Crystal Oscillator
Industrial Applications of Crystal Oscillator

17. Crystal Oscillator Circuit and Working
Colpitts Crystal Oscillator Application
Colpitts Oscillator is used to generate a sinusoidal output signal at very high frequencies.
Colpitts oscillator can be used as the different types of sensors such as temperature sensor.
Using of SAW device in Colpitts circuit it senses directly from its surface.

18. Crystal Oscillator Circuit and Working
Colpitts Crystal Oscillator Application

19. Crystal Oscillator Circuit and Working
Colpitts Crystal Oscillator Application
The applications of the Colpitts oscillators mainly involve where the wide range of frequencies is used.
It is used in undamped and continuous oscillation condition.
Using some devices in Colpitts circuit, we can achieve greater temperature stability and high frequency.
Colpitts used for the development of mobile communications and radio communications.

20. Crystal Oscillator Circuit and Working
Applications of Armstrong Crystal Oscillator
These are widely used in the regenerative radio receivers.
In that input, radio frequency signal from the antenna is coupled magnetically into the tank circuit through an additional winding.
Feedback is reduced to gain control in the feedback loop.
It produces a narrow-band radio-frequency filter and amplifier.
In this Crystal oscillator LC resonant circuit is replaced with feedback loops.

21. Crystal Oscillator Circuit and Working
Applications of Armstrong Crystal Oscillator

22. Crystal Oscillator Circuit and Working
Applications of Armstrong Crystal Oscillator
In Military and Aerospace
Used for the efficient communication system.
Crystal Oscillators are used in military and aerospace.
The communication system is to establish and for the navigation purpose and electronic warfare in the guidance systems

23. Crystal Oscillator Circuit and Working
Applications of Armstrong Crystal Oscillator
In Research and Measurement
The crystal oscillators are used in research and measurement for the celestial navigation and the space tracking purpose
The crystal oscillators are used in medical devices and in the measuring instruments.

24. Crystal Oscillator Circuit and Working
Industrial Applications of Crystal Oscillator
There are many industrial applications of the crystal oscillator.
They are widely used in computers.
Used in Instrumentation.
Used in digital systems.
Used in phase locked loop systems.
Used in Modems and marine
Used in telecommunications.

25. Crystal Oscillator Circuit and Working
Industrial Applications of Crystal Oscillator
Used in sensors.
Used in disk drives.
Used in engine controlling.
Used in clock and to trip computer.
Used in Stereo.
Used in GPS systems.

26. Crystal Oscillator Circuit and Working
Industrial Applications of Crystal Oscillator
Crystal oscillators are used in many consumer goods.
Used In cable television systems.
Used In video cameras.
Used In personal computers.
Used In toys and video games.
Used In cellular phones.
Used In radio systems.

27. Crystal Oscillator Circuit and Working
Conclusion
This is all about what is a Crystal Oscillator, its working and Applications. Quartz crystal is mainly used in radio-frequency (RF) oscillators. We have seen the circuit diagram working of crystal oscillator. Quartz crystal is the most common type of piezoelectric resonator, in oscillator circuits we are using them so it became known as crystal oscillators.