Patent ID: 8081049

Claim:
A band-pass filter device comprising: a plurality of band-pass filter elements on a principal plane of a substrate; wherein said band-pass filter elements correspond to a plurality of respective channels divided by frequency regions, and each have a plurality of piezoelectric resonators, and each of said piezoelectric resonators includes a piezoelectric film whose periphery is supported by said substrate, a first electrode formed on a lower surface of said piezoelectric film, a second electrode formed on an upper surface of said piezoelectric film and formed in a state of overlapping at least a part of said first electrode with said piezoelectric film interposed between said second electrode and said first electrode, a lower space formed between said substrate and said piezoelectric film, and an upper space formed over said piezoelectric film, said band-pass filter elements have a plurality of band-pass filter element groups, each band-pass filter element of one of said plurality of band-pass filter element groups has a plurality of piezoelectric resonators, and a piezoelectric film of each piezoelectric resonator has a resonance mode of a different frequency by being changed in length in a one-dimensional direction parallel with the principal plane of said substrate, and each band-pass filter element of another of said plurality of band-pass filter element groups has a plurality of piezoelectric resonators, and a piezoelectric film of each piezoelectric resonator has a resonance mode of a different frequency by being changed in length in two-dimensional directions parallel with the principal plane of said substrate.