| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve: broadband and matching improvement of an acoustic wave filter using a temperature compensation film; and suppression of resonance frequency shift. <P>SOLUTION: An acoustic wave filter includes a plurality of piezoelectric thin film resonators. Each of the piezoelectric thin film resonators includes: a substrate 10; a piezoelectric thin film 14 disposed on the substrate 10; a lower electrode 12 and an upper electrode 18 disposed with at least a part of the piezoelectric thin film interposed therebetween; a mass load film 24 for controlling frequency which is disposed in a resonance region 40 where the lower electrode 12 and the upper electrode 18 are opposed to each other, and has a shape different from that of the resonance region 40; and a temperature compensation film 16 which is disposed in the resonance region 40, and has a temperature coefficient of reverse code of a temperature coefficient of an elastic constant of the piezoelectric thin film 14. At least two of the plurality of piezoelectric thin film resonators are acoustic wave filter having different areas of the mass load films 24. <P>COPYRIGHT: (C)2013,JPO&INPIT |
