| 摘要 |
<p>There is provided an acoustic wave filter device capable of suppressing deterioration of balance in output and attaining an increased amount of attenuation on a lower side relative to a passband. In the acoustic wave filter device, the first to fourth longitudinally coupled resonator type surface acoustic wave filters (11 to 14) are configured such that the first and second longitudinally coupled resonator type surface acoustic wave filters (11 and 12) are connected to a first balanced signal terminal (6), the third and fourth longitudinally coupled resonator type surface acoustic wave filters (13 and 14) are connected to a first balanced signal terminal (7), and a transmission phase of a signal output from the first balanced signal terminal (6) relative to an input signal differs by 180 degrees with respect to a transmission phase of a signal output from the second balanced signal terminal (7) relative to an input signal. In addition, the number of pairs of electrode fingers of at least one of the IDTs of at least one of the first to fourth longitudinally coupled resonator type surface acoustic wave filters (11 to 14) is different from the number of pairs of electrode fingers of corresponding IDTs of the remaining first to fourth longitudinally coupled resonator type surface acoustic wave filters.</p> |
