SAW Resonator In RF Remote Control Application

SAW resonators provides reliable, fundamental-mode, quartz frequency stabilization of fixed-frequency transmitters operating at many frequencies such as 315Mhz, 433.92Mhz, 868.35Mhz etc, and usually is designed specifically for remote-control and wireless security transmitters, SAW resonators are designed to be the frequency control element in transmitters and receiver local oscillators, they allows reduced receiver bandwidths, which results in improved sensitivity and immunity to interference, now tighter center frequency tolerances are becoming more and more popular in Europe, so our parts provider can provide as tight as +/-50 kHz currently and ensures most units falls within +/- 20 kHz range, also they are quartz stabilized to ensure maximum temperature performance in a variety of applications.

SAW resonator devices in remote control transmitter application

A surface acoustic wave (SAW) is a wave that occurs when energy concentrates near the surface of an elastic body, and electronic devices to which this wave is applied are called SAW devices, such as SAW resonators commonly seen in RF remote control and receiver application.

The SAW resonators widely used are high-Q resonators, that can be realized by generating a standing wave between comb electrodes and increasing the number of electrode teeth.

There are two types of SAW resonators, one-port resonator and two-port resonator, one-port resonator has a structure of comb electrodes placed at the center and reflectors on both sides, a surface wave that has been excited by the comb electrodes is reflected by the reflectors, which then generates a standing wave, therefore, this resonator uses high Q, and it is applied mainly to oscillators and narrowband filters, while two-port resonator, because of its structure, is a narrowband filter, but it does use a high Q, and is generally used for oscillators and narrowband filters with a higher frequency band than one-port resonators.

For ISM or sub-Ghz bands such as 315 / 433 / 915 bands, one port resonator is mainly used, and application for one-port resonators are typically in modified colpitts oscillator configurations where the resonator is connected between the base of a transistor and ground.

There are many package or footprint for SAW resonators, they are packaged in both the traditional TO39-3 and a variety of surface-mount packages, the TO39 parts are shipped in antistatic shipping tubes and the SMT parts are shipped in tape-and-reel packages.

SAW resonators have been widely used in applications such as automotive keyless entry, tire pressure monitoring, door and gate openers, personal and home security, automated meter readers, wireless point of sale terminals, bar code readers, identification tags and computer peripherals.