Abstract: A filter device includes a filter between an input terminal and an output terminal, and an additional circuit connected in parallel with the filter between the input terminal and the output terminal. The additional circuit includes at least two longitudinally coupled resonators connected in parallel with each other and including longitudinally coupled resonators, and at least one capacitance element between the input terminal and the at least two longitudinally coupled resonators or between the output terminal and the at least two longitudinally coupled resonators. The average pitch of a plurality of electrode fingers of IDT electrodes of the longitudinally coupled resonator and the average pitch of a plurality of electrode fingers of IDT electrodes of the longitudinally coupled resonator are different from each other.

Abstract: An acoustic wave filter includes at least one serial arm resonance circuit on a path connecting input/output terminals, and at least one parallel arm resonance circuit between a node on the path and a ground, in which each of the at least one serial arm resonance circuit and the at least one parallel arm resonance circuit includes an acoustic wave resonator, a first parallel arm resonance circuit of the at least one parallel arm resonance circuit includes a bridging capacitor connected in parallel to the acoustic wave resonator, an anti-resonant frequency of the first parallel arm resonance circuit is positioned on a higher-frequency side than the pass band, and a resonant frequency of a first serial arm resonance circuit of the at least one serial arm resonance circuit is positioned on a lower-frequency side than the anti-resonant frequency of the first parallel arm resonance circuit.

Abstract: A multiplexer includes an antenna terminal, an inductance element, and a transmission-side filter and a reception-side filter connected to the antenna terminal. The transmission-side filter has a first pass band, and the reception-side filter has a second pass band. The reception-side filter is connected to the antenna terminal through the inductance element. A center frequency of the second pass band is higher than a center frequency of the first pass band. The reception-side filter includes parallel arm resonance portions including a first parallel arm resonance portion connected closest to the inductance element. An electrostatic capacitance of the first parallel arm resonance portion is larger than an electrostatic capacitance of any other parallel arm resonance portions.

Abstract: A multiplexer includes a filter on a first path connecting a common terminal and an input/output terminal, and a second filter on a second path connecting the common terminal and a second terminal, the second filter having a passband that overlaps a generation frequency of Rayleigh wave ripples in the filter. The filter includes series arm resonators on the first path and a parallel arm resonator, the series arm resonators and the parallel arm resonator utilize an SH wave as a main mode, and a number of electrode finger pairs of the series arm resonator is fewest among numbers of electrode finger pairs of the series arm resonators.

Abstract: A multiplexer includes a common terminal, a first filter connected to the common terminal, a wiring line connecting the common terminal and the reception filter to each other, a second filter connected to a connection node on the wiring line, a third filter connected to a connection node on the wiring line, a wiring line connecting the connection node and the transmission filter to each other, a wiring line connecting the connection node and the first filter to each other, and an inductor connected between a wiring region of the wiring line that extends from the connection node to the first filter and the ground or between the wiring line and the ground. The length of a portion of the wiring line extending from the common terminal to the connection node is longer than the length of a portion of the wiring line extending from the common terminal to the connection node.

Abstract: A filter includes a ladder filter including a first parallel arm resonator and a second parallel arm resonator, a longitudinally coupled resonator filter electrically connected in series to the ladder filter, a first ground terminal electrically connected to the first parallel arm resonator, a second ground terminal electrically connected to the second parallel arm resonator, a third ground terminal electrically connected to the longitudinally coupled resonator filter, a third signal path electrically connected to a first node on a first signal path electrically connecting the second parallel arm resonator to the second ground terminal and a second node on a second signal path electrically connecting the longitudinally coupled resonator filter to the third ground terminal, and an inductor electrically connected between the first node on the first signal path and the second ground terminal or between the second node on the second signal path and the third ground terminal.

Abstract: A multiplexer includes first and second filters and additional circuits. The first filter is coupled to transmit and antenna terminals, the second filter is coupled to receive and antenna terminals, one additional circuit is coupled to transmit and receive terminals, and another additional circuit is coupled to transmit and antenna terminals. Pass bands of the first and second filters are respectively first and second frequency bands, and the second frequency band including a center frequency higher than a center frequency of the first frequency band. The one additional circuit includes a first resonator group including first IDT electrodes aligned in a propagation direction of an acoustic wave. The other additional circuit includes a second resonator group including second IDT electrodes aligned in the propagation direction. An average pitch of electrode fingers is greater among the first IDT electrodes than the second IDT electrodes.

Abstract: A multiplexer includes a transmission-side filter, a reception-side filter, and a cancel circuit connected between a node M and a node N to cancel out a component in a predetermined frequency band that flows along first and second paths. The cancel circuit includes at least one longitudinally-coupled resonator. An average pitch between electrode fingers of interdigital transducer electrodes of the at least one longitudinally-coupled resonator is narrower than an average pitch between electrode fingers of interdigital transducer electrodes of each of series arm resonators and parallel arm resonators that determine the pass band of the transmission-side filter and an average pitch between electrode fingers of interdigital transducer electrodes of each of series arm resonators and parallel arm resonators that determine the pass band of the reception-side filter.

Abstract: A multiplexer includes a common terminal, a first terminal, a second terminal, a first filter device including acoustic wave resonators including series resonators and parallel resonators, an inductor provided between an acoustic wave resonator and the first terminal, and a second filter device. The first filter device further includes a first ground terminal to which a parallel resonator is electrically connected, a second ground terminal to which the parallel resonators are electrically connected, and a wiring provided between the inductor and an acoustic wave resonator. In the first filter device, the wiring is electrically connected to the first ground terminal, and the first ground terminal is not connected to the second ground terminal.

Abstract: A filter device utilizing surface acoustic waves includes one or more series arm resonators connected to each other along a path between a first input/output terminal and a second input/output terminal, and three or more parallel arm resonators each connected between a connection node provided on the path and ground and defining the pass band of the filter device. Parallel arm resonators having different anti-resonant frequencies from each other are included. Parallel arm resonators among the three or more parallel arm resonators are connected to the same connection node provided along the path. Remaining parallel arm resonators are connected to different connection nodes from the same connection node. The anti-resonant frequencies of the parallel arm resonators connected to the same connection node are identical and are the lowest anti-resonant frequencies among the anti-resonant frequencies of the three or more parallel arm resonators.

Abstract: A ladder filter includes at least one series arm resonator connected in a path between first and second input/output terminals, at least two parallel arm resonators each connected between a connection node in the path and a ground, and an inductor connected in series to the at least one series arm resonator. The inductor is closer to the first input/output terminal than are the at least one series arm resonator and the at least two parallel arm resonators. Of the at least two parallel arm resonators, a first parallel arm resonator connected closest to the second input/output terminal has the highest anti-resonant frequency.

Abstract: A duplexer includes elastic wave resonators disposed on a piezoelectric substrate to define a ladder elastic wave filter including shunt-arm resonators and series-arm resonators. The duplexer includes an inductance component connected between an antenna terminal and a ground potential. A transmitting filter includes the ladder elastic wave filter. The inductance component is disposed outside a short side of the piezoelectric substrate such that the electromagnetic coupling between the shunt-arm resonator located closest to a transmitting terminal in the ladder circuit configuration, and the inductance component is stronger than the electromagnetic coupling between the inductance component and the remaining shunt-arm resonators.

Abstract: A duplexer includes elastic wave resonators disposed on a piezoelectric substrate to define a ladder elastic wave filter including shunt-arm resonators and series-arm resonators. The duplexer includes an inductance component connected between an antenna terminal and a ground potential. A transmitting filter includes the ladder elastic wave filter. The inductance component is disposed outside a short side of the piezoelectric substrate such that the electromagnetic coupling between the shunt-arm resonator located closest to a transmitting terminal in the ladder circuit configuration, and the inductance component is stronger than the electromagnetic coupling between the inductance component and the remaining shunt-arm resonators.

Abstract: An acoustic wave filter device includes at least one series arm resonator and a parallel arm resonator. The series arm resonators and the parallel arm resonator are defined by acoustic wave resonators, an interdigital transducer electrode of the series arm resonators is an apodized interdigital transducer electrode subjected to apodization weighting, in the interdigital transducer electrode of the parallel arm resonator, an intersecting portion includes a central region and low acoustic velocity regions provided at both outer side portions of the central portion, an acoustic velocity of an acoustic wave in the low acoustic velocity region is lower than an acoustic velocity of an acoustic wave in the central region, and a high acoustic velocity region where an acoustic velocity of an acoustic wave is higher than that of the low acoustic velocity region is provided at an outer side portion of each of the low acoustic velocity regions.

Abstract: A ladder filter includes series-arm resonators each including an IDT electrode and a reflector, and a parallel-arm resonator. In at least one of the series-arm resonators, where a wavelength that is determined by an electrode finger pitch of the IDT electrode is ?, an electrode finger center-to-center distance between an electrode finger located closest to the reflector among electrode fingers of the IDT electrode and an electrode finger located closest to the IDT electrode among electrode fingers of the reflector is less than about 0.5?, and an anti-resonant frequency of the at least one of the series-arm resonators is higher than an anti-resonant frequency of at least another one of the series-arm resonators.

Abstract: A multiplexer includes a transmission filter and a reception filter that are connected to a common terminal, and a cancellation circuit that is connected to the common terminal and a node on a transmission path and that offsets a component in a certain frequency band flowing through the transmission filter. The cancellation circuit includes a capacitive element connected to the common terminal, and a longitudinally-coupled resonator including a first end connected to the capacitive element and a second end connected to the node with no capacitive element interposed therebetween. An impedance in a reception band when viewing the cancellation circuit from the common terminal side is higher than an impedance in the reception band when viewing the cancellation circuit from the node side.

Abstract: A ladder filter defines a transmission filter and has a structure such that a resonator located closest to an input terminal is a parallel-arm resonator, and the parallel-arm resonator located closest to the input terminal includes a plurality of division resonators connected in parallel. At least one division resonator has a resonant frequency and an anti-resonant frequency that are located outside a passband of the ladder filter, and the remaining division resonators and parallel-arm resonators each have an anti-resonant frequency located within the passband.

Abstract: A ladder filter includes at least one series arm resonator connected in a path between first and second input/output terminals, at least two parallel arm resonators each connected between a connection node in the path and a ground, and an inductor connected in series to the at least one series arm resonator. The inductor is closer to the first input/output terminal than are the at least one series arm resonator and the at least two parallel arm resonators. Of the at least two parallel arm resonators, a first parallel arm resonator connected closest to the second input/output terminal has the highest anti-resonant frequency.

Abstract: A composite filter apparatus includes a common terminal, a transmission-side terminal, a reception-side terminal, a transmission filter, and a reception filter with a pass band higher than the pass band of the transmission filter. The transmission filter is connected between the common terminal and the transmission-side terminal and the reception filter is connected between the common terminal and the reception-side terminal. An inductor is provided between the common terminal and the reception filter in a path between the common terminal and the reception-side terminal. The resonant frequency of a parallel-arm resonator closest to the common terminal in the reception filter is lower than a high end frequency of the pass band of the transmission filter and is lower than the resonant frequencies of the other parallel-arm resonators in the reception filter.

Abstract: A ladder filter in which the pass band is defined by serial arm resonators and first and second parallel arm resonators includes the serial arm resonators, the first and second parallel arm resonators, and a third parallel arm resonator. The third parallel arm resonator is connected in parallel to the first parallel arm resonator, the electrostatic capacitance of the third parallel arm resonator is smaller than that of the first parallel arm resonator, and the anti-resonant frequency of the third parallel arm resonator is positioned outside the pass band of the ladder filter. The anti-resonant frequency of the first parallel arm resonator is positioned at the high frequency side of the anti-resonant frequencies of the second parallel arm resonators.