You’ll Find Them In Electronics You Have in Your Home!
Crystal oscillators are utilized in a wide range of electronic applications. A high-stability, high-performance oscillator can be created inexpensively and easily using a crystal oscillator circuit.
Crystal oscillators can be utilized to create a low-cost clock signal for use in a digital or logic device. A crystal oscillator also can be utilized to offer a reliable and precise radio frequency (RF) signal source. As a result, radio hams or radio amateurs frequently use crystal oscillators in radio transmitter circuits, for example.
Why Do We Use Quartz Crystals?
Crystal oscillators are formed of quartz, a naturally occurring type of silicon. Most of the quartz utilized in electronics these days is synthesized. Quartz crystals have some unique properties highly valued in electronic circuits.
An electrical circuit’s “crystal” is not a whole, organically produced crystal. It’s a slab of quartz cut from a whole crystal. The slab will vibrate in different modes depending on how it is sliced in relation to the crystal’s axis. The frequency of oscillation is determined by the crystal thickness, the mass of the electrodes plated onto it, and the cutting axis.
Crystals, when used in an electrical circuit, work as a very high-quality-tuned circuit. Furthermore, they are extremely stable, with little variation in resonance frequency with temperature or time.
This makes quartz crystal oscillators an inexpensive and highly reliable time-keeping tool within electronic circuits. More than 2 billion quartz crystal oscillators are manufactured annually. Many are used in time-keeping devices like clocks and wristwatches, but they also play a huge part in virtually all testing and measurement equipment and a significant percentage of all electronic circuits.
Understanding the Piezoelectric Effect
The capacity of some materials to create an electric charge in response to mechanical stress is known as the piezoelectric effect, something which is utilized heavily in a crystal oscillator.
The direct piezoelectric effect (the creation of electricity when stress is applied) is reversible, which means that materials that show the direct piezoelectric effect (the generation of electricity when stress is applied) can also display the reverse piezoelectric effect (the generation of stress when an electric field is applied).
When a piezoelectric material is subjected to mechanical stress, the charge centers change in the material, resulting in an external electrical field. An outside electrical field compresses or stretches the piezoelectric material.
The Piezoelectric Effect in a Crystal Oscillator
The piezoelectric effect is required for a crystal oscillator to function. Mechanical stress in a crystal is converted to a voltage and vice versa through this phenomenon. The piezoelectric effect transforms electrical impulses to mechanical stress, which is then subjected to the crystal’s very high Q mechanical resonances and reflected back into the electrical circuit.
The piezoelectric effect is beneficial in a variety of applications, including sound creation and detection, high-voltage generation, electronic frequency generation, and ultra-fine optical assembly focusing. It also serves as the foundation for a variety of atomic-resolution scientific instruments, such as scanning probe microscopes. The piezoelectric effect is also used in more everyday applications, such as in cigarette lighters as an ignition source.
Crystal Oscillator Amplification
When a crystal is mechanically deformed, a voltage is created at its faces, thanks to the piezoelectric effect. When a voltage is applied to the crystal’s faces, it mechanically distorts.
To keep the oscillation going, the quartz resonator’s electrical signal is amplified and supplied back to the crystal. The specifics of how this feedback is provided result in a variety of oscillator circuits. With crystals, the Armstrong, Colpitts, and Hartley and oscillator topologies can all be employed. The Colpitts topology is the most popular since it does not require inductors.
Crystal Oscillators are Useful in Many Ways
A crystal oscillator is a frequency-selective electronic oscillator circuit. The oscillator frequency keeps time and stabilizes frequencies. Crystal oscillators employ quartz crystals or piezoelectric materials like polycrystalline ceramics as piezoelectric resonators.
A crystal oscillator uses electrostriction (inverse piezoelectricity), which is the shape change of a quartz crystal under an electric field. When a voltage is supplied to the crystal’s electrodes, it changes form. It creates a little voltage as it returns to its previous shape.
Quartz oscillates at a consistent resonant frequency. Once a quartz crystal’s frequency is set (by the mass of electrodes linked to the crystal, its orientation, temperature, and other parameters), it retains it with remarkable stability. This is what makes crystal oscillators so useful in so many applications, as they can stably and reliably release a voltage on a timer.
