 A 16 MHz ceramic resonator | |
| Component type | Electromechanical |
|---|---|
| Working principle | Piezoelectricity,Resonance |
Aceramic resonator is anelectronic component consisting of a piece of apiezoelectricceramic material with two or more metal electrodes attached. When connected in anelectronic oscillator circuit,resonant mechanical vibrations in the device generate anoscillating signal of a specificfrequency. Like the similarquartz crystal, they are used inoscillators for purposes such as generating theclock signal 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-stabilitypiezoelectric ceramics, generallylead zirconate titanate (PZT) which functions as a mechanicalresonator. In operation, mechanical vibrations induce an oscillating voltage in the attached electrodes due to thepiezoelectricity of the material. The thickness of the ceramic substrate determines theresonant frequency of the device.
A typical ceramic resonator package has either two or threeconnections. 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.[1] They come in bothsurface-mount andthrough-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 toground.[2][3]
Ceramic resonators can be used as the source of theclock signal fordigital circuits such asmicroprocessors where the frequency accuracy is not critical.[4] 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 areference clock orsignal generator in electronic circuitry due to its low cost and smaller size.
The lower Q and higher frequency range achievable can be beneficial in use ofTCXOs, 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.[5]
Ceramic resonators look similar to ceramic filters. Ceramic filters are frequently used in theIF stages ofsuperheterodyne 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.[6]