| 摘要 |
(Problems) There is a problem of degradation in balance characteristics with a longitudinal mode type surface acoustic wave filter having unbalanced-balanced type terminals. (Constitution) A longitudinal mode type surface acoustic wave filter comprising a first IDT electrode 102, second and third IDT electrodes 103 and 104, and first and second reflector electrodes 105 and 106 is formed on a piezoelectric substrate 101. The upper electrode 102a of the first IDT electrode 102 is connected to one of balanced type terminals 107, and the lower electrode 102b of the first IDT electrode 102 is connected to the other balanced type terminal 108. Also, the lower electrode 103a of the second IDT electrode 103 is connected to an unbalanced type terminal 109, and the lower electrode 103b is grounded. The lower electrode 104b of the third IDT electrode 104 is connected to the unbalanced type terminal 109, and the upper electrode 103a is grounded. |
