| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a BAW filter capable of uniformizing characteristics in a plurality of resonators. Ž<P>SOLUTION: The BAW filter includes: a support substrate 1; an insulating layer 3 provided on one surface of the support substrate 1; and three resonators 2a-2c provided at one surface side of the support substrate 1 each. In the three resonators 2a-2c, the two resonators 2a, 2b compose a filter circuit, and the remaining resonator 2c is a dummy resonator 2c not connected to both the resonators 2a, 2b electrically. The three resonators 2a-2c and an etching hole 10a, which includes a cavity provided at a lower side of the respective resonators 2a-2c, is used for introducing an etching liquid, and is provided in the insulating layer 3, are in a threefold rotational symmetry arrangement, thus uniformizing the positional relationship to the etching hole 10a in the respective resonators 2a-2c, thereby uniformizing the characteristics of the resonators 2a, 2b for composing the filter circuit. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
