Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode facing each other across at least a part of the piezoelectric film; and an insertion film inserted in the piezoelectric film, located in at least a part of an outer peripheral region within a resonance region where the lower electrode and the upper electrode face each other across the piezoelectric film, and not located in a center region of the resonance region, wherein a difference between a total film thickness of the piezoelectric film and the insertion film in a first region, in which the insertion film is inserted, within the resonance region and a film thickness of the piezoelectric film in a second region, in which the insertion film is not inserted, is less than a film thickness of the insertion film.

Abstract: A filter includes: piezoelectric thin film resonators, each including a substrate, a piezoelectric film located on the substrate, a lower electrode and an upper electrode facing each other across at least a part of the piezoelectric film, and an insertion film inserted in the piezoelectric film, located in at least a part of an outer peripheral region within a resonance region, and not located in a center region of the resonance region, the resonance region being a region where the lower electrode and the upper electrode face each other across the piezoelectric film, wherein at least two piezoelectric thin film resonators out of the piezoelectric thin film resonators have different widths of the insertion films within the resonance regions.

Abstract: A piezoelectric thin film resonator includes a substrate, a lower electrode provided on the substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film. At least a portion of the upper electrode and that of the lower electrode oppose each other through the piezoelectric film, and at least a portion of the periphery of the upper electrode is reversely tapered.

Abstract: A duplexer includes a transmission filter and a reception filter having different passbands, wherein: first resonators that are series resonators or parallel resonators included in the transmission and reception filters so as to form a skirt characteristic at a guard band side are a temperature compensated type piezoelectric thin film resonator or a surface acoustic wave resonator using Love waves, and second resonators that form a skirt characteristic at an opposite side to the guard band are one of a temperature non-compensated type piezoelectric thin film resonator, a surface acoustic wave resonator using a lithium tantalate substrate or a substrate made by bonding a lithium tantalate substrate on a sapphire substrate, and a surface acoustic wave resonator using Love waves.

Abstract: An acoustic wave device includes: a substrate; a lower electrode formed on the substrate; at least two piezoelectric films formed on the lower electrode; an insulating film located between the at least two piezoelectric films; and an upper electrode formed on the at least two piezoelectric films, wherein an outer periphery of an uppermost piezoelectric film out of the at least two piezoelectric films in a region in which the lower electrode and the upper electrode face each other is positioned further in than an outer periphery of the upper electrode.

Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode located to sandwich the piezoelectric film; a load film formed from patterns in a resonance region in which the lower electrode and the upper electrode face each other across the piezoelectric film, wherein the patterns are formed so as to surround a center of the resonance region and intersect with a pathway extending from the center to an outer periphery of the resonance region.

Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film provided on the substrate; a lower electrode and an upper electrode that are opposed to each other to put at least a part of the piezoelectric film therebetween; and an insertion film that is inserted into the piezoelectric film in a resonance region where at least the part of the piezoelectric film is put between the lower electrode and the upper electrode, at least a part of the insertion film corresponding to an outer circumference region in the resonance region being thicker than a part of the insertion film corresponding to a central region in the resonance region.

Abstract: A filter includes: a plurality of piezoelectric thin film resonators, each having a multilayered film including a lower electrode located on a substrate, a piezoelectric film located on the lower electrode, and an upper electrode located on the piezoelectric film so as to face the lower electrode, wherein at least two piezoelectric thin film resonators have thick film portions, in each of which the multilayered film is thicker in at least a part of an outer peripheral portion than in an inner portion of a resonance region in which the lower electrode and the upper electrode face each other across the piezoelectric film, and lengths of the thick film portions from edges of the resonance regions are different from each other in the at least two piezoelectric thin film resonators.

Abstract: An electronic circuit includes a plurality of duplexers that are coupled to an antenna terminal and have a pass band different from each other and a plurality of acoustic wave filters that are respectively coupled between the antenna terminal and the plurality of the duplexers, wherein filter characteristics of a first acoustic wave filter of the plurality of the acoustic wave filters are set so as to allow passage of a signal in both a pass band for transmitting and a pass band for receiving of a first duplexer of the plurality of the duplexers that is coupled to the first acoustic wave filter and suppress passage of a signal in both a pass band for transmitting and a pass band for receiving of a second duplexer of the plurality of the duplexers that is different from the first duplexer.

Abstract: An acoustic wave filter includes series resonators and parallel resonators that have a piezoelectric film on an identical substrate and have a lower electrode and an upper electrode, wherein: one of the series resonators and the parallel resonators have a temperature compensation film on a face of the lower electrode or the upper electrode that is opposite to the piezoelectric film in a resonance region, the compensation film having an elastic constant of a temperature coefficient of which sign is opposite to a sign of a temperature coefficient of an elastic constant of the piezoelectric film; and the other have an added film on the same side as the temperature compensation film on the lower electrode side or the upper electrode side compared to the piezoelectric film in the resonance region in the one of the series resonators and the parallel resonators.

Abstract: A piezoelectric thin-film resonator includes: a lower electrode provided on a substrate; a piezoelectric film that is provided on the lower electrode and includes at least two layers; an upper electrode that is provided on the piezoelectric film and has a region sandwiching the piezoelectric film with the lower electrode and facing the lower electrode; and an insulating film that is provided in a region in which the lower electrode and the upper electrode face each other and between each of the at least two layers, wherein an upper face of the insulating film is flatter than a lower face of the insulating film.

Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film provided on the substrate; a lower electrode and an upper electrode that sandwich at least a part of the piezoelectric film and face with each other; and an inserted film that is inserted in the piezoelectric film, is provided on an outer circumference region in a resonance region in which the lower electrode and the upper electrode sandwich the piezoelectric film and face with each other, is not provided in a center region of the resonance region, and has a cutout in the resonance region.

Abstract: An acoustic wave device including: a substrate; a piezoelectric film formed on the substrate; an lower electrode provided on a first surface of the piezoelectric film; an upper electrode provided on a second surface of the piezoelectric film opposite to the first surface; and a mass loading film having a first pattern and a second pattern in a resonance portion in which the lower electrode and the upper electrode face each other through the piezoelectric film, the first pattern having portions and the second pattern having portions interlinking the portions of the first pattern.

Abstract: An acoustic wave device includes: a piezoelectric thin film resonator including: a substrate; a lower electrode formed on the substrate; at least two piezoelectric films formed on the lower electrode; an insulating film sandwiched by the at least two piezoelectric films; and an upper electrode formed on the at least two piezoelectric films, wherein an area of the insulating film within a resonance region, in which the lower electrode and the upper electrode face each other across the at least two piezoelectric films, is different from an area of the resonance region.

Abstract: An acoustic wave device includes a main resonator and a sub resonator each having a substrate, a lower electrode provided on the substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on an upper side of the piezoelectric film. A frequency control film is provided on an upper side of a resonance area in which the upper electrode and the lower electrode face each other in at least one of the main resonator and the sub resonator. The frequency control film has multiple convex patterns, and the convex patterns are arranged with a common pitch for spurious adjustment and with different areas in the main resonator and the sub resonator.

Abstract: An acoustic wave device includes: a piezoelectric film located on a substrate; a lower electrode and an upper electrode facing each other across the piezoelectric film; a temperature compensation film located on a surface, which is opposite to the piezoelectric film, of at least one of the lower electrode and the upper electrode and having a temperature coefficient of elastic constant opposite in sign to a temperature coefficient of elastic constant of the piezoelectric film; and an additional film located on a surface of the temperature compensation film opposite to the piezoelectric film and having an acoustic impedance greater than an acoustic impedance of the temperature compensation film.

Abstract: A method of manufacturing an elastic wave device is provided with a lamination step of forming, on a substrate (1), a plurality of elastic wave devices, each of which includes a lower electrode (2), a piezoelectric film (3), and an upper electrode (4); a measuring step for measuring the operation frequency distribution of the elastic wave devices on the substrate (1); and an adjusting step for forming an adjusting region, in which the thickness of the elastic wave device is different from the thicknesses of other portions in a resonance portion of each elastic wave device, corresponding with the distribution of the operation frequencies. The adjusting region is formed so that the size of the area of the adjusting region of the resonator portion of each elastic wave device is different in accordance with the operation frequency distribution that is measured. Thus, the frequency characteristics of the elastic wave devices are easily adjusted by a small number of steps.

Abstract: An acoustic wave device includes: a first piezoelectric thin film resonator including a first lower electrode, a first upper electrode and a first piezoelectric film sandwiched between the first lower and upper electrodes; a decoupler film provided on the first upper electrode; and a second piezoelectric thin film resonator provided on the decoupler film and including a second lower electrode, a second upper electrode and a second piezoelectric film sandwiched between the second lower and upper electrodes, wherein the first piezoelectric film and the second piezoelectric film comprise aluminum nitride and include an element increasing a piezoelectric constant of the aluminum nitride.

Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode located to sandwich the piezoelectric film; a load film formed from patterns in a resonance region in which the lower electrode and the upper electrode face each other across the piezoelectric film, wherein the patterns are formed so as to surround a center of the resonance region and intersect with a pathway extending from the center to an outer periphery of the resonance region.

Abstract: A method of manufacturing a ladder filter including first and second resonators includes: forming a piezoelectric film on an entire surface of a substrate that has respective lower electrodes of the first and second resonator formed thereon, an conductive film on the piezoelectric film, and a second film on the conductive film; forming a pattern of the second film in a prescribed region in the second area; forming a first film on an entire surface of the substrate; etching the first film, forming a pattern of the first film, the second film and the conductive film in the second area, and forming a pattern of the first film and the conductive film in the first area, to form respective upper electrodes from the conductor film; and thereafter, etching the piezoelectric film to form respective patterns of the piezoelectric film in the first and second areas, respectively.