| 摘要 |
<p>A 5-IDT type longitudinally-coupled resonator type elastic wave filter device with narrowly-pitched electrode finger sections improves steepness of the filter characteristics. It is a 5-IDT type longitudinally-coupled resonator type elastic wave filter device (1) having first through a fifth IDTs (11a-11e) wherein, when the total numbers of the electrode fingers provided at the narrowly-pitched electrode finger sections in a first region (R1) and a fourth region (R4) are denoted respectively as Nx, and the total numbers of the electrode fingers provided at the narrowly-pitched electrode finger sections in a second region (R2) and a third region (R3) are denoted respectively as Ny, the average value of the cycles of the electrode fingers is set greater for the narrowly-pitched electrode finger sections in the regions with the greater total numbers between the total numbers Nx of the electrode fingers and the total numbers Ny of the electrode fingers than the narrowly-pitched electrode finger sections in the regions with the smaller total numbers, and cycles of the electrode fingers are set narrower for the IDT electrodes that are included in the regions with the greater total numbers out of the first, the third, and the fifth IDT electrodes (11a, 11c, 11e) than the IDT electrodes that are included in the regions with the smaller total numbers of electrode fingers, except at the parts where the narrowly-pitched electrode finger sections are provided.</p> |
