SAW oscillator

SAW (Surface Acoustic Wave) can obtain a high quality factor like crystal. The principle of SAW is that when a metal plate is hit with a hammer, a specific vibration is generated depending on the thickness, material, and surface area of the metal plate, and the vibration is transmitted to the surface. A comb-shaped electrode IDT (Inter Digital Transducer) resonates at a specific frequency, reflects it with the DBR, and amplifies the energy of the resonance frequency. The wavelength λ is determined by the distance between the IDT electrodes. The electrodes are constructed on the Piezoelectric Substrate, and the waveform is transmitted through the surface of the Substrate by the piezoelectric effect.

If the number of comb-shaped electrodes increases, the value of Quality Factor can be increased. Unlike crystal, it can directly oscillate high frequency, so it has good phase noise characteristics and there is no noise factor such as PLL circuit.

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