Understanding SAW Duplexers: Basics, Working, and Manufacturers

SAW duplexers play a critical role in RF communication by enabling simultaneous transmission and reception. This guide covers their basics, working principles, and key manufacturers. A duplexer is a device that separates two frequency bands that are close to each other. It utilizes narrow band filters to perform the filtering of respective bands.

It’s a 3-port device. The major application of a duplexer is to share the same RF antenna between a transmitter and receiver, as illustrated in Figure 1 below.

Figure 1: SAW Duplexer

Since it can be used for simultaneous transmission and reception of frequency bands, it is especially used in FDD (Frequency Division Duplexing) wireless systems like LTE, UMTS, etc.

SAW Duplexer Working Principle

SAW duplexers operate based on the generation of acoustic waves from electrical signals. The generation of mechanical energy (e.g., SAW) from electrical energy and vice versa is accomplished by the use of a piezoelectric substrate material. Its construction involves inter-digital transducers (IDTs) and gratings.

Figure 2: SAW Generation

SAW devices use the piezoelectric effect of materials such as quartz, lithium tantalate, lithium niobate, and lanthanum gallium silicate for the conversion of acoustic waves to electrical signals and vice versa. Figure 2 depicts the generation of Surface Acoustic Waves.

Figure 3: SAW Duplexer Frequency Response

Figure 3 shows the frequency response of the duplexer. There are two frequency bands displayed. As illustrated, when there’s low attenuation in one band’s curve, there is very high attenuation for the other curve. This facilitates easy separation of two frequency bands using a SAW duplexer.

The SAW duplexer operates based on the surface acoustic wave propagation principle. It allows bidirectional communication over a single path, as explained above.

Conclusion

SAW duplexers are indispensable in modern RF systems. Choosing reliable manufacturers ensures optimal performance and durability for communication systems.