A ceramic resonator is an
electronic component
An electronic component is any basic discrete electronic device or physical entity part of an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singula ...
consisting of a piece of a
piezoelectric
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied stress (mechanics), mechanical s ...
ceramic
A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...
material with two or more metal electrodes attached. When connected in an
electronic oscillator
An electronic oscillator is an electronic circuit that produces a periodic, oscillating or alternating current (AC) signal, usually a sine wave, square wave or a triangle wave, powered by a direct current (DC) source. Oscillators are found ...
circuit,
resonant mechanical vibrations in the device generate an
oscillating signal of a specific
frequency
Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...
. Like the similar
quartz crystal
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical fo ...
, they are used in
oscillator
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...
s for purposes such as generating the
clock signal
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and ...
used to control timing in computers and other digital logic devices, or generating the carrier signal in analog radio transmitters and receivers.
Ceramic resonators are made of high-stability
piezoelectric
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied stress (mechanics), mechanical s ...
ceramics, generally
lead zirconate titanate
Lead zirconate titanate, also called lead zirconium titanate and commonly abbreviated as PZT, is an inorganic compound with the chemical formula . It is a ceramic perovskite material that shows a marked piezoelectric effect, meaning that the comp ...
(PZT) which functions as a mechanical
resonator
A resonator is a device or system that exhibits resonance or resonant behavior. That is, it naturally oscillates with greater amplitude at some frequencies, called resonant frequencies, than at other frequencies. The oscillations in a reso ...
. In operation, mechanical vibrations induce an oscillating voltage in the attached electrodes due to the
piezoelectricity
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress.
The piezoel ...
of the material. The thickness of the ceramic substrate determines the
resonant frequency
Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...
of the device.
Packages
A typical ceramic resonator package has either two or three
connections. The two pin devices are typically just the resonators themselves, while three and sometimes four pin devices are filters, often used in AM and FM broadcast radios as well as many other RF applications. They come in both
surface-mount
Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred ...
and
through-hole varieties with a number of different footprints. The oscillation takes place across two of the pins (connections). The third pin (if present; typically the center pin) is connected to
ground.
Applications
Ceramic resonators can be used as the source of the
clock signal
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and ...
for
digital circuits
Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. It deals with the relationship between binary inputs and outputs by passing electrical signals through ...
such as
microprocessors
A microprocessor is a computer processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, and control circuitry r ...
where the frequency accuracy is not critical. Quartz has a 0.001% frequency tolerance, while PZT has a 0.5% tolerance.
They are used in timing circuitry for a wide array of applications such as TVs, VCRs, automotive electronic devices, telephones, copiers, cameras, voice synthesizers, communication equipment, remote controls and toys. A ceramic resonator is often used in place of quartz crystals as a
reference clock or
signal generator
A signal generator is one of a class of Electronics, electronic devices that generates electrical signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typ ...
in electronic circuitry due to its low cost and smaller size.
The lower Q and higher frequency range achievable can be beneficial in use of
TCXOs, temperature-compensated crystal oscillators. The frequency of the oscillator can be "pulled" in wider range than with high-Q crystal. This allows wider range of adjustments, which may be critical in devices operating in extreme (especially low) temperatures where the crystal's own temperature-frequency dependence could take it outside of the pullable range for the desired frequency.
Ceramic filters
Ceramic resonators look similar to ceramic filters. Ceramic filters are frequently used in the
IF stages of
superheterodyne receivers. Originally ceramic filters were used as very low cost filters for broadcast radio receivers, both medium wave sets with typical IFs of 455 kHz and FM broadcast sets with IF stages at around 10.7 MHz. However, as the performance has significantly improved, they are used in many other RF applications as well.
Quartz resonators and filters
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See also
* Electronic oscillator
An electronic oscillator is an electronic circuit that produces a periodic, oscillating or alternating current (AC) signal, usually a sine wave, square wave or a triangle wave, powered by a direct current (DC) source. Oscillators are found ...
* Crystal oscillator
A crystal oscillator is an electronic oscillator Electrical circuit, circuit that uses a piezoelectricity, piezoelectric crystal as a frequency selective surface, frequency-selective element. The oscillator frequency is often used to keep trac ...
* Crystal filter
References
{{Electronic component
Resonators