To provide the multiple mode surface acoustic wave filter which is made suitable for a board-frequency band and where attenuation of a blocked band is high.
Let the number of electrode fingers of an interdigital electrode 4 in the middle of a transducer adopting an electrode configuration of 1st, 2nd and 3rd interdigital electrodes 3, 4, 5 be N, and the left-right interdigital electrodes 3, 5 whose number of electrode fingers is nearly equal to each other and N/2 or below, are arranged symmetrically to the left and right of the 2nd interdigital electrode 4, reflectors 2, 6 whose number of electrode fingers is smaller than that of the left and right interdigital electrodes 3, 5 are arranged to both sides of the transducer of the three-interdigital electrode configuration, and a distance D2 between the reflector 2 and the interdigital electrode 3 and a distance D3 between the reflector 6 and the interdigital electrode 5 are differentiated from a distance D1 between the interdigital electrodes 3, 4 and between the interdigital electrodes 4, 5, so as to configure the surface acoustic wave filter having two block frequency bands.
| WO/2004/107571 | SURFACE WAVE DEVICE WITH WEIGHTED TRANSDUCER |
| JPH1056353 | SURFACE ACOUSTIC WAVE FILTER |
WATANABE KAZUSHI
HOSAKA NORIO
