| 摘要 |
PROBLEM TO BE SOLVED: To reduce insertion loss in surface acoustic wave devices including balance-unbalance conversion functions. SOLUTION: The surface acoustic wave device 100A includes: first and second filters 20A, 40A, namely surface acoustic wave filters including not less than three odd numbers of IDTs, respectively; an unbalanced terminal 10 to which an unbalanced signal is inputted; a first balanced terminal 12 from which a signal in the same phase as that of the unbalanced signal is outputted; and a second balanced terminal 14 from which a signal in a phase opposite to the that of unbalanced signal is outputted. In each of the first and second filters 20, 40, one electrode is commonly connected to the unbalanced terminal 10 in a first center IDT22A and a second center IDT42A that are positioned at the center. Also, the number of electrode fingers of the first center IDT22A is odd, and the number of electrode fingers of the second center IDT42A is even. This configuration suppresses notches in a passband, thus reducing the insertion losses. COPYRIGHT: (C)2011,JPO&INPIT |
