A crystal resonator includes a crystal element and excitation electrodes. The crystal element has a pair of principal surfaces parallel to an X′-axis and a Z′-axis. The X′-axis is an axis of rotating an X-axis as a crystallographic axis of a crystal in a range of 15 degrees to 25 degrees around a Z-axis as a crystallographic axis of the crystal. The Z′-axis is an axis of rotating the Z-axis in a range of 33 degrees to 35 degrees around the X′-axis. The excitation electrodes are formed on the respective principal surfaces of the crystal element. Elliptical mesa portions or elliptical inverted mesa portions are formed on the respective principal surfaces. The mesa portions project from outer peripheries of the principal surfaces. The inverted mesa portions are depressed from the outer peripheries of the principal surfaces.

There is provided an acoustic resonator including: a resonance part including a first electrode, a second electrode, and a piezoelectric layer interposed between the first and second electrodes; and a substrate provided below the resonance part, wherein the substrate includes at least one via hole penetrating through the substrate and a connective conductor formed in the via hole and connected to at least one of the first and second electrodes. Therefore, reliability of the connective conductor formed in the substrate may be secured.

There is provided an acoustic resonator including: a resonance part including a first electrode, a second electrode, and a piezoelectric layer interposed between the first and second electrodes; and a substrate provided below the resonance part, wherein the substrate includes at least one via hole penetrating through the substrate and a connective conductor formed in the via hole and connected to at least one of the first and second electrodes. Therefore, reliability of the connective conductor formed in the substrate may be secured.

A duplexer includes: a first filter connected between a common terminal and a first terminal and including first series and first parallel resonators; a second filter having a passband higher than that of the first filter, connected between the common terminal and a second terminal, and including second series and second parallel resonators; a first chip including the first series and second parallel resonators mounted thereon; a second chip including the first parallel and second series resonators mounted thereon, wherein when GA and HGB represent temperature coefficients of antiresonant frequencies of the first and second series resonators, and HGA and GB represent temperature coefficients of resonant frequencies of the first and second parallel resonators, a magnitude relationship among GA, GB, HGA, and HGB is none of a relationship in which GA (GB) differs from HGA (HGB), and GB (GA) and HGB (HGA) are located between GA (GB) and HGA (HGB).

An acoustic wave filter includes a substrate, a first resonator disposed on the substrate, a second resonator disposed on the substrate to be spaced apart from the first resonator, a connector electrically connecting the first and second resonators, and a variable capacitor formed in the connector to tune a pass band frequency of the acoustic wave filter.

An acoustic wave filter includes a substrate having voids formed therein; a first resonator disposed on one or more of the voids, and a second resonator disposed on other of the voids. A first trimming layer is provided in the first resonator, and a second trimming layer is provided in the second resonator. The second trimming layer is formed of a material having an etching rate for a given etchant different from that of the first trimming layer.

A frequency adjustment method of a vibrator element includes preparing a vibrator element that has a vibrating arm, a first weight placed on one principal surface of the vibrating arm, and a second weight placed on the other principal surface of the vibrating arm, in which the first weight has a non-overlapping region which does not overlap the second weight in a plan view in a normal direction of the principal surface, preparing a substrate including a wiring portion, and fixing the vibrator element to the substrate by causing the other principal surface side of the vibrator element to face the substrate side, and irradiating the non-overlapping region of the first weight with an energy ray from one principal surface side, removing a portion of the non-overlapping region of the first weight, and adjusting a resonance frequency of the vibrating arm.

A frequency adjustment method of a vibrator element includes preparing a vibrator element that has a vibrating arm, a first weight placed on one principal surface of the vibrating arm, and a second weight placed on the other principal surface of the vibrating arm, in which the first weight has a non-overlapping region which does not overlap the second weight in a plan view in a normal direction of the principal surface, preparing a substrate including a wiring portion, and fixing the vibrator element to the substrate by causing the other principal surface side of the vibrator element to face the substrate side, and irradiating the non-overlapping region of the first weight with an energy ray from one principal surface side, removing a portion of the non-overlapping region of the first weight, and adjusting a resonance frequency of the vibrating arm.

An acoustic wave resonator includes: a piezoelectric substrate; an IDT located on the piezoelectric substrate and including comb-shaped electrodes facing each other, each of the comb-shaped electrodes including: electrode fingers exciting an acoustic wave; and a bus bar to which the electrode fingers are connected; a dielectric film located on the piezoelectric substrate in an overlap region, where the electrode fingers of one of the comb-shaped electrodes and the electrode fingers of the other overlap, so as to cover the electrode fingers; and an additional film located on the dielectric film in the overlap region and having a density greater than that of the dielectric film, and of which a film thickness in edge regions corresponding to both edges of the overlap region in an extension direction of the electrode fingers is greater than a film thickness in a central region sandwiched between the edge regions in the overlap region.

A piezoelectric component includes a support substrate; a piezoelectric element having both ends fixed to the support substrate, so as to be oscillatable; a pair of terminal electrodes located below the ends of the piezoelectric element, respectively; a pair of capacitance-forming electrodes each having a greater width than the piezoelectric element, extending from the pair of terminal electrodes, respectively, toward a center of the piezoelectric element; and excitation electrodes disposed on a first principal surface and a second principal surface of the piezoelectric element, respectively, the excitation electrodes facing each other so that a facing region in which the excitation electrodes overlap with each other as seen in a transparent plan view is defined therebetween, at least part of a region of the pair of capacitance-forming electrodes which protrudes outside the facing region in a width direction thereof as seen in a plan view, being covered with an insulating film.