Abstract: A piezoelectric thin-film resonator includes a substrate, a lower electrode provided on the substrate, a piezoelectric film provided on the substrate and the lower electrode, an upper electrode provided on the piezoelectric film, and an additional pattern, a cavity being formed between the lower electrode and the substrate in a resonance portion in which the lower electrode and the upper electrode face each other through the piezoelectric film, the additional pattern being provided in a position that is on the lower electrode and includes an interface between the resonance portion and a non-resonance portion.

Abstract: A duplexer includes an unbalanced transmitting filter; a balanced receiving filter; a transmitting port connected to the transmitting filter; and a first receiving port and a second receiving port connected to the receiving filter. The duplexer also includes an electromagnetic coupling portion connected between the transmitting port and the first receiving port and between the transmitting port and the second receiving port. The electromagnetic coupling portion adjusts the phase between electric power that flows from the transmitting port to the first receiving port and electric power that flows from the transmitting port to the second receiving port.

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 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: An acoustic wave filter including piezoelectric thin film resonators, in which at least two of the piezoelectric thin film resonators including: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode located across at least a part of the piezoelectric film; a mass load film for a frequency control located in a resonance region where the lower electrode and the upper electrode face each other, and having a shape different from that of the resonance region; and a temperature compensation film having a temperature coefficient of an elastic constant opposite in sign to that of the piezoelectric film, at least a part of the temperature compensation film being located between the lower electrode and the upper electrode in the resonance region, and areas of mass load films of said at least two of the piezoelectric thin film resonators are different from each other.

Abstract: In a high frequency device, resonators (IDT capacitors) that function as capacitors are included in a lumped constant balun included in a filter or duplexer, and furthermore, the resonance frequency of the IDT capacitors is set higher than the passband frequency of the filter. This improves the capacitor Q value, thus enabling the realization of a low-loss balance filter.

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. The sub resonator has a mass addition film on the upper electrode in a resonance area in which the upper electrode and the lower electrode face each other. At least one of the main resonator and the sub resonator is provided with a frequency control film on an upper side of the resonance area, and the frequency control film has a weight per unit area smaller than a weight of the mass addition film per unit area.

Abstract: The filter includes: a primary transducer connected to a primary terminal; a secondary transducer connected to a plurality of secondary terminals; and a coupling transducer for mechanically coupling the primary transducer and the secondary transducer.

Abstract: A filter includes a plurality of primary resonators connected to a serial arm, a plurality of secondary resonators connected to a parallel arm, a primary inductor connected to at least one of the plurality of primary resonators and a secondary inductor connected to at least one of the plurality of secondary resonators. The primary inductor is arranged so as not to be connected to a path between the secondary resonator to which the secondary inductor is connected in parallel and the primary resonator that is connected to the secondary resonator to which the secondary inductor is connected in parallel.

Abstract: There is provided a filter including a first resonator, a second resonator in which an excitation efficiency is reduced more than the first resonator, and an inductor connected in parallel with the second resonator.

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: 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 that is located opposite the lower electrode across at least a part of the piezoelectric film. A mass load film is provided on the upper electrode. The mass load film includes a plurality of concave or convex patterns in at least a region that faces the lower electrode. The plurality of concave or convex patterns are densely arranged in a central portion of the region and are sparsely arranged in a peripheral portion of the region.

Abstract: A duplexer includes an unbalanced transmitting filter; a balanced receiving filter; a transmitting port connected to the transmitting filter; and a first receiving port and a second receiving port connected to the receiving filter. The duplexer also includes an electromagnetic coupling portion connected between the transmitting port and the first receiving port and between the transmitting port and the second receiving port. The electromagnetic coupling portion adjusts the phase between electric power that flows from the transmitting port to the first receiving port and electric power that flows from the transmitting port to the second receiving port.

Abstract: The filter includes one or more series resonators and one or more parallel resonators. An inductance is connected in series to at least a parallel resonator of the parallel resonators, and a antiresonance frequency of the parallel resonator to which the inductance is connected in series is equal to or higher than that of the series resonators. The duplexer, the communication module and the communication device are provided with the filter.

Abstract: There is provided a piezoelectric thin film resonator that decreases only transverse mode waves selectively while maintaining resonance characteristics due to original thickness longitudinal vibration. The piezoelectric thin film resonator includes: a piezoelectric film (14); a first electrode (15a) formed on a first principal surface of the piezoelectric film (14); and a second electrode (13) formed on a second principal surface of the piezoelectric film (14) opposite to the first principal surface. The resonator has a resonance region (20) where the first electrode (15a) and the second electrode (13) are opposed to each other. An electrically discontinuous portion (18a) that is insulated from the first electrode (15a) is provided on the first principal surface of the piezoelectric film (14) in the resonance region (20), and the electrically discontinuous portion (18a) is surrounded by the first electrode (15a) on the first principal surface.

Abstract: A filter includes at least one series resonator and parallel resonators, the at least one series resonator and the parallel resonators including excitation electrodes and reflectors, the parallel resonators having different resonance frequencies, and at least one of the parallel resonators other than the parallel resonator having the highest resonance frequency being configured to have a pitch of reflectors that is smaller than that of excitation electrodes.

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 with a reduced filter loss is provided. The duplexer includes two or more filters F1 and F2 that are connected to a common terminal and that have different passbands. At least one of the filters F1 and F2 includes a plurality of series resonators S1 to Sn connected in series to a path between an input terminal and an output terminal of the filter, and parallel resonators P1 to Pm connected in parallel to the above-mentioned path. An inductance L1 is connected in parallel to at least one of the series resonators, and the series resonator S1 having the inductance L1 connected in parallel thereto is divided into a plurality of resonators S11 to S13 connected in series.

Abstract: A method of producing a piezoelectric thin film resonator is provided. A sacrificial layer is formed on a part of the piezoelectric film. The sacrificial layer is patterned, and thereafter an upper electrode is formed on the piezoelectric layer. The method further includes removing the sacrificial layer formed on the piezoelectric layer; and patterning the piezoelectric film. In the step of removing the sacrificial layer, the sacrificial layer is removed such that at least a portion of the periphery of the upper electrode has a reversely tapered shape that reflects the tapered portion of the sacrificial layer, and in the step of patterning the piezoelectric film, the piezoelectric film is removed such that a lower end of the reversely tapered periphery of the upper electrode is placed so as to coincide with or to be in the vicinity of an end portion of the patterned piezoelectric film.

Abstract: A method for manufacturing an acoustic wave device includes: bonding a piezoelectric substrate to a first surface of a first support substrate; thinning the piezoelectric substrate after the bonding to thus form a piezoelectric layer; forming a first electrode on a first surface of the piezoelectric layer; forming holes in the first support substrate located below the first electrode; and bonding a second support substrate to a second surface of the first support substrate opposite to the first surface after the forming of holes.