| 摘要 |
An acoustic surface wave filter element provided with two input and two output pins connected with the input and the output interdigital electrodes, respectively and an earth pin connected with a filter element shield casing is disposed on one surface of a circuit board, with the five pins extending through corresponding through holes in the circuit board to the other surface of the circuit board on which the pins are connected with corresponding conductive circuit patterns of the circuit board. The circuit patterns include a first signal pattern to be connected with one of the input pins, a first earth pattern connected with the other of the input pins, a second and a third signal pattern connected with one and another of the output pins, and a second earth pattern connected with the earth pin of the filter element. The first and the second signal pattern have end portions opposedly positioned to each other, and an earth pattern portion is positioned between the opposed end portions of the first and the second signal pattern to connect the first and the second earth pattern with each other. Portions of the patterns positioned beneath the filter element are arrayed symmetrically about an axis lying on the center of the terminal of the end portion of the first signal pattern and external between the second and third signal patterns.
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