Filter, the composite filter, which equipped with filter mounting structure, an integrated circuit chip, electronic equipment, and their frequency characteristics changing

摘要

PROBLEM TO BE SOLVED: To separately change the center frequency of a resonator, the coupling coefficient between resonance modes, and the external Q value to a desired value by an electric-to-mechanical-converted driving force.;SOLUTION: The dual mode elastic wave resonator 7a has a resonance mode connection 6 separated from an input electrode 2 and an output electrode 3 via respective narrow gaps 4, 5. Conductive pillars 27, 28, 29 and a feeding pad 31 support the electrodes 2, 3, a resonator 7a, and a connection 6 on a board, where they are vibrated freely, and the counter electrodes 10, 11, 21, 23 are formed under them via a narrow space. In this arrangement, changing the voltage of a power source 25 causes an electrostatic force to change the distortion of the resonator 7a, thus changing the center resonance frequency of the resonator 7a. Also, changing the voltage of power sources 16, 17 causes distortions of the electrodes 2, 3 to change, thus changing the areas of respective end faces of the electrodes 2, 3 and of the resonator 7a that are opposite to each other. Then an energy exchange status is changed between the electrodes 2, 3 and the resonator 7a, and ultimately changing the external Q value. Further, changing the voltage of a power source 25 changes also a distortion of the connection 6, leading to a change of the coupling coefficient between the resonance modes.;COPYRIGHT: (C)2004,JPO