Patent ID: 7545077

Claim:
A filter comprising multiple piezoelectric thin-film resonators each having a substrate, a lower electrode formed on the substrate, a piezoelectric film formed on the lower electrode, and an upper electrode provided on the piezoelectric film so that the upper electrode and the lower electrode face each other across the piezoelectric film, the multiple piezoelectric thin-film resonators including a first resonator in which at least a part of an outer curved portion of the piezoelectric film of the first resonator is located further out than an outer curved portion of a region defined so that the upper electrode and the lower electrode face each other across the piezoelectric film, the multiple piezoelectric thin-film resonators including a second resonator in which at least a part of an outer curved portion of the piezoelectric film of the second resonator substantially coincides with an outer curved portion of a region defined so that the upper electrode and the lower electrode face each other across the piezoelectric film or is further in than the outer curved portion of the region defined so that the upper electrode and the lower electrode face each other across the piezoelectric film.