| 摘要 |
PROBLEM TO BE SOLVED: To provide a triple mode crystal filter whose resistive component of input and output impedance is in matching with resistive components of impedances of circuits in front of and behind a mounted IF circuit and in which spurious radiation in the vicinity of a pass band is considerably suppressed. SOLUTION: The triple mode crystal filter is configured by arranging first, second and third electrodes on an AT-cut crystal substrate along the Z' axis direction at prescribed gaps and arranging a fourth electrode in opposition to the first, second and third electrodes. Sizes of the first, second and third electrodes in the X axis direction are differently selected, so that the filter is in matching with the resistive components of the impedances of the circuits in front of and behind the mounted IF circuit. COPYRIGHT: (C)2005,JPO&NCIPI
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