| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave device having balance-unbalance converting function, in which balancing between balance terminal 418 and 419 is improved. SOLUTION: A longitudinal coupled resonator type surface acoustic wave element 401 comprising three interdigital electrode parts 407, 408, 409 is constituted on a piezoelectric substrate 20. By using two elements 401, 402, balance/ unbalance conversion is made possible, and the input impedance and the output impedance are mutually made different by about four times, Pitches of the respective interdigital pitches in the elements 401, 402 are made different to the right and the left. In the case of structure, where one-terminal pair surface acoustic wave resonators 403-406 are connected in series with at least one out of inputs and outputs of elements, the pitches of the resonators are made different to the right and the left.
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