| 摘要 |
<p>An acoustic wave filter device having a balanced-to-unbalanced conversion function, in which the signal balance between a pair of balanced terminals is improved, is provided. An acoustic wave filter device (100) in which, on a piezoelectric substrate (101), one end of at least of one longitudinally coupled resonator type acoustic wave filter (110) and one end of at least one acoustic wave filter (120) among the rest of acoustic wave filters are commonly connected and connected to an unbalanced terminal (104), and the other ends of the longitudinally coupled resonator type acoustic wave filters (110 and 120) are electrically connected to first and second balanced terminals (104a and 104b), respectively, in which a signal input from the unbalanced terminal is configured such that the phases of a signal output from the first balanced terminal and a signal output from the second balanced terminal are approximately 180 degrees, and in which an propagation direction of an acoustic wave in the longitudinally coupled resonator type acoustic wave filter (110) and a propagation direction of an acoustic wave in the second longitudinally coupled resonator type acoustic filter (120) are different from each other.</p> |
