Patent ID: 7482895

Claim:
A surface acoustic wave filter, comprising: a piezoelectric substrate; a first electrode pattern having at least four interdigital transducer electrodes and at least one inner reflector electrode arranged on a surface of the piezoelectric substrate and on a first surface acoustic wave propagation path; reflector electrodes arranged at least at both ends of the first electrode pattern including the at least four interdigital transducer electrodes; a second electrode pattern having a plurality of interdigital transducer electrodes arranged on the surface of the piezoelectric substrate and on a second surface acoustic wave propagation path which is different from the first surface acoustic wave propagation path; and reflector electrodes arranged at least at both ends of the second electrode pattern including the plurality of interdigital transducer electrodes, wherein the at least four interdigital transducer electrodes on the first surface acoustic wave propagation path are electrically connected in series by connecting wirings, each of the plurality of interdigital transducer electrodes on the second surface acoustic wave propagation path is connected between the connecting wirings and ground, and at least some of the connecting wirings are arranged between the first electrode pattern and the second electrode pattern, wherein the at least one inner reflector electrode has a fewer number of electrode fingers than the reflector electrodes arranged at both ends of the first electrode pattern, and at least one adjacent pair of the interdigital transducer electrodes of the first electrode pattern has no reflector electrode therebetween, and wherein some terminals of the plurality of interdigital transducer electrodes arranged on the second surface acoustic wave propagation path are connected to ground, and the other terminals of the plurality of interdigital transducer electrodes are connected to different connecting wirings respectively.