| 摘要 |
A surface acoustic wave device, and a duplexer and a communication device using the same are provided to implement good communication quality with low interference with other communication standard by preparing an attenuation electrode at a high frequency side around pass band. A first surface acoustic wave filter(1) forms a ladder type filter circuit. A second surface acoustic wave filter(2) has a pass band with frequency higher than a pass band of the first surface acoustic wave filter. The first surface acoustic wave filter includes a serial arm surface acoustic wave resonator(7a,7b,7c,7d), at least one parallel arm surface acoustic wave resonator(8a,8b,8c) and an additional surface acoustic wave resonator(15a). The serial arm surface acoustic wave resonator includes an IDT electrode connected to a serial arm of the ladder type filter circuit. The parallel arm surface acoustic wave resonator includes an IDT electrode connected to a parallel arm of the ladder type filter circuit. The additional surface acoustic wave resonator includes an IDT electrode connected in parallel with the serial arm surface acoustic wave resonator as having a resonant frequency higher than the pass band of the second surface acoustic wave filter. |
