SAW filter

SAW filter

(Surface Acoustic Wave filter) A semiconductor device that is used to filter out desired frequencies. Widely used in mobile phones to filter both RF and IF frequencies, a SAW filter uses the piezoelectric effect to turn the input signal into vibrations that are turned back into electrical signals in the desired frequency range.

Two sets of metal electrodes like teeth on a comb are adhered to a quartz crystal and spaced apart (in microns) based on the required frequencies. As few as five and as many as 5,000 electrodes are used. An intriguing analogy from Bruce Thomas at Sawtek, a subsidiary of TriQuint Semiconductor, is that the first set of electrodes is like throwing a large log into a pond, which makes huge waves that cause little sticks to bounce out at the other side (second set).

TC-SAW and BAW
SAW filters are sensitive to high temperatures, and temperature-compensated SAW (TC-SAW) filters were designed to retain their integrity under such conditions. However, TC-SAWs do not support the higher LTE frequencies, but bulk acoustic wave (BAW) filters do. As a result, SAW filters are often used for lower frequencies, while BAWs, which are twice as costly, are used for the high end. See RF filter.
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Satellite radio is just one of the many applications for our SAW filter products.
This SAW filter is designed for use in a global navigation satellite system.
The world SAW filter market is growing primarily due to the mobile devices market.
By using a balanced output SAW filter instead of a single output one, the RF designer can suppress the use of the transformer and impedance networks (see Figure 2).
New SAW Filter Doubles Passband From 50 MHz to 100 MHz With Breakthrough Design for 2-Way Set-Top Box, Modem Applications
The model VS-500 SAW stabilized, voltage-controlled oscillator operates at the fundamental frequency of the internal SAW filter.
TriQuint's New Ultra Low Loss, High Rejection GPS SAW Filter Adds To Company's Broad PND Portfolio
The signal is then upconverted to IF and the I and Q channels are combined and moved off chip to the external SAW filter.
With an estimated 66% GPS SAW filter share, TriQuint Semiconductor leads in supplying low-cost, high-performance devices for PNDs made by three of the top four(1) major manufacturers that include Garmin, Tom-Tom, Mio Technology and Magellan.
A transversal SAW filter generally consists of input and output transducers deposited on a highly polished piezoelectric substrate such as quartz, lithium tantalate or lithium niobate.
TriQuint's latest additions to its SAW filter product portfolio are designed to further support network infrastructure roll-outs and upgrades across both emerging, cost-sensitive markets as well as in mature, feature-rich networks," said TriQuint's Director for Networks Product Marketing, Paul Gilgallon.
Eigen functions for the SAW filter design (first used by DeVries[1]) were simple sinc functions in the frequency domain whose inverse Fourier transforms were cosine bursts of particular durations.