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: An elastic wave filter device includes a longitudinally coupled resonator-type elastic wave filter formed on a piezoelectric substrate; and a ladder-type elastic wave filter connected to the resonator-type elastic wave filter. The resonator-type filter includes an input IDT and an output IDT. The ladder-type filter includes a series arm resonator and a parallel arm resonator. A first ground electrode connected to the parallel arm resonator is electrically separated from a second ground electrode connected to at least one of the input IDT and the output IDT.

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 duplexer includes an acoustic wave element having a first terminal and a second terminal; a substrate; a first columnar conductor electrically connected to the first terminal, and drawn to a back surface of the substrate while partially in the substrate; a second columnar conductor electrically connected to the second terminal, and drawn to the back surface of the substrate while partially in the substrate. Additionally, a first ground pattern region is between the first columnar conductor drawn part and the second columnar conductor drawn part on the back surface of the substrate; a second ground pattern region is electrically connected to the first ground pattern region and arranged in the part not including the part between the first columnar conductor drawn part and the second columnar conductor drawn part; and a third columnar conductor electrically is connected to the first ground pattern region while partially in the substrate.

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 filter includes one or a plurality of parallel resonators coupled in parallel and one or a plurality of a film bulk acoustic resonators coupled in series, the film bulk acoustic resonator having a substrate, a lower electrode, a piezoelectric membrane, and an upper electrode, wherein: at least one of the lower electrode and the upper electrode has a thick membrane region having a thickness larger than that of a center portion of a resonance region at an edge of the resonance region, the resonance region being a region where the lower electrode and the upper electrode face with each other through the piezoelectric membrane; and a width of the thick membrane region is smaller than a wavelength of an acoustic wave propagating in a direction crossing a thickness direction of the piezoelectric membrane.

Abstract: A production method of an electronic component includes: forming a sheet having a resin layer and a metal layer formed under the resin layer; bonding the sheet to a substrate so that the metal layer is arranged on a functional portion of an acoustic wave element formed on the substrate, a frame portion surrounding the functional portion is formed between the metal layer and the substrate, a cavity is formed on the functional portion by the metal layer and the frame portion, and the resin layer covers the metal layer and the frame portion.

Abstract: An elastic wave apparatus includes a balanced-unbalanced transforming function, and an elastic wave filter and a multilayer wiring board on which the elastic wave filter is mounted. The elastic wave filter includes an unbalanced terminal and first and second balanced terminals. External electrodes used are provided on the multilayer wiring board. A first internal line connects the first balanced terminal and the external electrode. A second internal line connects the second balanced terminal and the external electrode. The lengths or shapes of the first internal line and the second internal line are set so that a capacitance used for the improvement of a balance is generated in an adjacent area A where the first internal line and the second internal line are adjacent to each other. In the adjacent area A, the directions of currents passing through the first internal line and the second internal line are the same.

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: 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: A small-sized surface acoustic wave filter device having favorable filter characteristics includes a transmission-side surface acoustic wave filter chip including a ladder surface acoustic wave filter unit located on a piezoelectric substrate. The ladder surface acoustic wave filter unit includes a series arm connected between an input pad and an output pad and a plurality of resonators and including at least one first resonator connected to the input pad or the output pad. A die-attach surface is provided with an inductor connected to the first resonator. The inductor is arranged such that at least a portion thereof faces the first resonator and does not face any of the plurality of resonators and other than the first resonator.

Abstract: A ladder filter includes at least one series resonator connected in series between an input terminal and an output terminal, at least one parallel resonator connected in parallel with the at least one series resonator, and an inductor connected in parallel with the at least one series resonator. The at least one series resonator and the inductor generate a first attenuation pole at a frequency equal to or lower than a frequency band defined by the at least one series resonator and the at least one parallel resonator. The first attenuation pole is located at a frequency that is equal to or higher than a resonance frequency of a parallel resonator that is included in the at least one parallel resonator and has a highest resonance frequency and that is equal to or lower than a high-frequency end of the pass band.

Abstract: An elastic wave device includes an unbalanced terminal and first and second balanced terminals. A longitudinally-coupled-resonator-type first elastic wave filter is provided between the unbalanced terminal and the first balanced terminal. An elastic wave filter, which is connected in parallel with the first elastic wave filter, is connected between the unbalanced terminal and the second balanced terminal. The current paths through which IDT electrodes of the elastic wave filters of the elastic wave device are connected to ground terminals, are not symmetrical.

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 branching filter includes a ladder-type elastic wave filter unit connected between an antenna terminal and a transmission signal terminal and a longitudinally coupled resonator-type elastic wave filter unit connected between an antenna terminal and first and second balanced reception signal terminals while maintaining the isolation characteristics between the transmission signal terminal and the first and second reception signal terminals. In a duplexer, a transmission signal propagation direction is perpendicular or substantially perpendicular to each of a first reception signal propagation direction and a second reception signal propagation direction.

Abstract: A ladder filter includes at least one series resonator connected in series between an input terminal and an output terminal, at least one parallel resonator connected in parallel with the at least one series resonator, an additional resonator connected in series between the at least one series resonator and one of the input terminal and the output terminal, and an inductor connected in series to the additional resonator, the additional resonator having a resonance frequency higher than an anti-resonance frequency of the at least one series resonator.

Abstract: A multiplexer that includes three or more band-pass filters having different pass bands and has a reduced size, includes a duplexer and a third band-pass filter connected to an antenna terminal, the duplexer and the third band-pass filter are connected in parallel, the duplexer includes a first band-pass filter having a first pass band and a second band-pass filter having a second pass band different from the first pass band, and the third band-pass filter has a third pass band different from the first and second pass bands.

Abstract: Disclosed is a method for manufacturing an RF device. The method comprises the steps of (a) forming a metal sheet where interior structure of the RF device is formed; (b) attaching a plastic material housing to the formed metal sheet; and (c) performing silver plating on the RF device on which the plastic material housing is attached.

Abstract: The present disclosure relates to a hybrid transformer duplexer apparatus. The hybrid transformer duplexer apparatus includes an autotransformer having a first port, a second port and a tap coupled to a first antenna port. A step-down transformer has a primary winding with a first terminal coupled to the first port of the autotransformer and a second terminal coupled to the second port of the autotransformer, and a secondary winding having a third terminal coupled to a second antenna port and a fourth terminal coupled to a common node.

Abstract: An elastic-wave filter device includes a package substrate and filter mounting pattern provided on a first main surface of the package substrate on which a longitudinally coupled resonator-type elastic-wave filter is mounted, a back-side terminal pattern is provided on a second main surface thereof, and an internal electrode pattern is provided inside the package substrate. When seen in plan view from a direction perpendicular or substantially perpendicular to the first main surface of the substrate body, first via conductors electrically connecting a ground pattern element of the filter mounting pattern connected to a ground pad of the longitudinally coupled resonator-type elastic-wave filter and an internal ground pattern element of the internal electrode pattern are arranged asymmetrically with respect to a center line X-X passing through an input pattern element of the filter mounting pattern and through two output pattern elements.

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 duplexer includes a transmission filter connected between a common terminal and a transmission terminal, a reception filter connected between the common terminal and a reception; and a capacitor connected in parallel with the transmission filter and the reception filter between the transmission terminal and the reception terminal and has a capacitance so that a phase difference between a signal passing from the transmission terminal to the reception terminal through the transmission filter and the reception filter and a signal passing from the transmission terminal to the reception terminal through the capacitor, or connected in parallel with the reception filter between the common terminal and the reception terminal and has a capacitance so that a phase difference between a signal passing from the common terminal to the reception terminal through the reception filter and a signal from the common terminal to the reception terminal through the capacitor.

Abstract: A branching filter includes a longitudinally-coupled-resonator-type elastic wave filter having a balanced-unbalanced transformation function and the branching filter has excellent balance characteristics and a small size. The branching filter includes a ladder elastic wave filter chip and a longitudinally-coupled-resonator-type elastic wave filter chip. An antenna back-surface electrode and an antenna electrode pad are connected to each other via a first wiring provided in a wiring substrate. The antenna electrode pad and a longitudinally-coupled-resonator-type elastic wave filter are connected to each other via a second wiring provided on a piezoelectric substrate. The second wiring extends in a first direction and a first functional electrode and a second functional electrode provided on the piezoelectric substrate are axisymmetrically arranged with respect to each other about a central axis that extends in the first direction of the second wiring.

Abstract: A surface acoustic wave filter includes an arrangement of transducers having at least one first transducer one second transducer and one third transducer. The at least one first transducer is connected to the input terminal and a terminal for applying a reference potential. The second transducer is connected to the first output terminal and the terminal for applying the reference potential. The third transducer is connected to the second output terminal and the terminal for applying the reference potential. A capacitor is connected to at least one of a first and second output terminal in such a way that the capacitor is connected between the first and second output terminals or between one of the first and second output terminals and the terminal for applying the reference potential.

Abstract: In an acoustic wave filter, a notch resonator is connected in series or parallel with a plurality of acoustic wave resonators connected in a ladder shape. The notch resonator has a main resonant frequency that is substantially equal to a sub-resonant frequency of the acoustic wave resonators. With this configuration, the occurrence of sub-resonant responses in filter characteristics can be suppressed, resulting in an improvement in communication characteristics.

Abstract: A boundary acoustic waves device includes a piezoelectric substrate having piezoelectricity, interdigitated electrodes formed on the piezoelectric substrate, a first medium formed on the piezoelectric substrate so as to cover the interdigitated electrode, and a second medium formed on the first medium. The interdigitated electrodes include a plurality of electrode fingers and bus bars that connect ends of the plurality of electrode fingers. A third medium is formed on the first medium. The second medium and the third medium are in contact with the first medium. The first medium, the second medium, and the third medium are formed of different materials. The first medium, the second medium, and the third medium are different in a ratio in length of a part with the third medium formed with respect to a length of a propagation path of boundary acoustic waves in a cross-section perpendicular to a longitudinal direction of the electrode fingers, in the longitudinal direction of the electrode fingers.

Abstract: The present disclosure teaches a filtering device. The filtering device comprises a transforming unit, at least a first filtering element and a complementary filtering unit. The filtering device of the present disclosure allows an isolation of radio signals within a selected frequency band. Frequency bands closely-spaced to the selected frequency band may be suppressed. The present disclosure provides a reliable and almost identical response to temperature changes for the pass band within the selected frequency band and the stop bands closely-spaced to the selected frequency band. The filtering device withstands temperature changes without affecting a filtering performance different to the prior art. The present disclosure further provides a method for filtering an input signal as well as a computer program product for the manufacture of the filtering device and a computer program product for the carrying out of the method of filtering.

Abstract: A bulk acoustic wave (BAW) filter device includes a first port, a second port, a first coupled resonator filter stage, a second coupled resonator filter stage and a filter section. The first coupled resonator filter stage includes a first BAW resonator connected to the first port and a second BAW resonator acoustically coupled to the first BAW resonator. The second coupled resonator filter stage includes a third BAW resonator connected to the second port and a fourth BAW resonator acoustically coupled to the third BAW resonator. The filter section includes a fifth BAW resonator, the fifth BAW resonator connected between the second BAW resonator and the fourth BAW resonator.

Abstract: An acoustic wave device includes a piezoelectric substrate, interdigital electrodes arranged on the piezoelectric substrate, a first dielectric element arranged between the interdigital electrodes, a second dielectric element that covers the interdigital electrodes and the first dielectric element, and an adjustment element that has been formed on the first dielectric element. The adjustment element has been formed from a material whose specific gravity is greater than that of the first dielectric element and that of the second dielectric element.

Abstract: Antenna duplexer (1) has first filter (3) passing a signal in a first frequency band and second filter (4) passing a signal in a second frequency band higher than the first frequency band, and first filter (3) includes series resonator (7) having the lowest antiresonance frequency and other series resonators. The propagation angle of the main elastic wave of series resonator (7) having the lowest antiresonance frequency and that of the main elastic wave of the other resonators are made different from each other so that an electromechanical coupling coefficient of series resonator (7) having the lowest antiresonance frequency becomes smaller than that of the other resonators.

Abstract: An acoustic wave device includes: a piezoelectric substrate; a dielectric layer formed on the piezoelectric substrate; and first and second comb-tooth electrodes formed on the dielectric layer, the dielectric layer having a first thickness between the first comb-tooth electrodes and the piezoelectric substrate and a second thickness between the second comb-tooth electrodes and the piezoelectric substrate, the first and second thicknesses being different from each other.

Abstract: A duplexer includes a package substrate having layers stacked, a transmission filter and a reception filter that are provided on an upper surface of a first layer that is one of the layers of the package substrate, the transmission and reception filters being acoustic wave filters, a metal pattern provided on the upper surface of the first layer and formed to surround the transmission and reception filters, a transmission line provided on an upper surface of a second layer that is one of the layers of the package substrate and is positionally lower than the first layer, the transmission line electrically connecting the transmission filter and a transmission terminal together, and a reception line that is provided on the upper surface of the second layer and electrically connects the reception filter and a reception terminal. The thickness of the first layer is greater than that of the second layer.

Abstract: An antenna duplexer includes first and second filters connected to an antenna terminal. The first filter has a passband of a low frequency band. The second filter has a passband of a high frequency band. The second filter is a ladder-type filter including series-arm resonators and parallel-arm resonators. At least one parallel-arm resonator out of the parallel-arm resonators has a main resonance and an auxiliary resonance. Attenuation poles caused by the main resonance and the auxiliary resonance are within the low frequency band. This antenna duplexer has a high attenuation characteristic and a high isolation characteristic while maintaining a low insertion loss.

Abstract: A filter element includes a plurality of multilayer filters that are connected in cascade, each of the plurality of multilayer filters including a plurality of piezoelectric thin-film resonators stacked vertically, each of the piezoelectric thin-film resonators including a piezoelectric film and a pair of first electrodes between which the piezoelectric film is interposed, and a capacitor connected between an input terminal of one of the plurality of multilayer filters of a preceding stage and an input terminal of another one of the plurality of multilayer filters of a following stage, exciting directions of piezoelectric thin-film resonators to which the input terminals of the multilayer filters of the preceding and following stages are connected being opposite to each other.

Abstract: A demultiplexer has a common terminal, a transmission terminal, and a reception terminal, and furthermore includes a transmission filter connected between the common terminal and the transmission terminal, a reception filter connected between the common terminal and the reception terminal, and a phase shift circuit connected in series to the reception filter connected between the common terminal and the reception terminal. A node on the line from the phase shift circuit to the common terminal or the transmission terminal, and a node on the line from the phase shift circuit to the reception terminal are coupled via a reactance. Accordingly, it is possible to fundamentally reduce or eliminate the situation in which transmission signals from the transmission filter arrive at the reception circuit, and improve isolation.

Abstract: A single-chip duplexer, interfacing a receiver and a transmitter with a common antenna, includes transmit and receive filters, an annular sealing ring and a conductive stripe. The transmit filter is connected between the antenna and the transmitter, and has a transmit passband. The receive filter is connected between the antenna and the receiver, and has a receive passband different from the transmit passband. The annular sealing ring is connected between a surface of the chip and a surface of a cap to form a sealed cavity between the chip and the cap. The conductive stripe extends across at least a portion of the surface of the chip between the transmit filter and the receive filter, the conductive stripe being directly connected to the sealing ring and electrically connected to ground. The conductive stripe provides at least one of magnetic shielding and capacitive shielding between the transmit filter and the receive filter.

Abstract: A duplexer includes a reception filter that is connected between a reception terminal and an antenna terminal and includes one or a plurality of series resonators that are acoustic wave resonators, and a transmission filter that is connected between a transmission terminal and the antenna terminal and includes one or a plurality of acoustic wave resonators, a resonance frequency of a first series resonator that is one of the one or the plurality of series resonators and is closest to the antenna terminal in the reception filter being higher than an upper limit frequency of a reception band of the reception filter.

Abstract: An acoustic wave resonator that is excellent in terms of return loss characteristics at the resonant and anti-resonant frequencies and that is capable of effectively reducing loss includes an IDT electrode in which a plurality of first electrode fingers and a plurality of second dummy electrode fingers are connected to a first common electrode, a plurality of second electrode fingers and a plurality of first dummy electrode fingers are connected to a second common electrode. Apodization weighting is applied in the acoustic wave propagation direction. The metallization ratio of a non-crossing region is relatively high compared with the metallization ratio of a crossing region in the acoustic wave propagation direction.

Abstract: An acoustic wave element includes: resonators 2 each including an electrode to excite acoustic waves; a power supply wiring portion 3 that is disposed so as to connect the resonators 2 electrically; a piezoelectric substrate 4 on which the resonators 2 and the power supply wiring portion 3 are formed; a second medium 5 that is formed on the piezoelectric substrate 4 so as to cover the resonators 2; and a third medium 6 that is formed on the piezoelectric substrate 4 so as to cover at least the second medium 5 and the power supply wiring portion 3. A side surface 34 of the power supply wiring portion 3 that is in contact with a surface of the piezoelectric substrate 4 forms an obtuse first angle ? with respect to the surface 4a of the piezoelectric substrate 4.

Abstract: An acoustic wave filter device includes a plurality of acoustic wave filters disposed on the same piezoelectric substrate, and achieves enlargement of out-of-passband attenuation without a large increase in its size. For at least the first acoustic wave filter, ends of second IDTs and of third IDTs connected to first and second balanced terminals, the ends being connected to a ground potential, are connected to a common connection line, the common connection line is connected to a ground terminal by a ground line, and a distance between a connection point, at which the ground line is connected to the common connection line, and the first balanced terminal, and a distance between the connection point and the second balanced terminal, is the same or substantially the same.

Abstract: A resonant device includes first and second piezoelectric thin film resonators. The first piezoelectric thin film resonator includes a substrate, a first lower electrode formed on the substrate, a first piezoelectric film formed over the first lower electrode, and a first upper electrode formed on the piezoelectric film and opposed to the first lower electrode. The second piezoelectric thin film resonator includes a second lower electrode formed above the first upper electrode, a second piezoelectric film formed over the second lower electrode, and a second upper electrode formed on the piezoelectric film and opposed to the second lower electrode. The first membrane region in which the first lower electrode opposes to the first upper electrode through the first piezoelectric film and a second membrane region in which the second lower electrode opposes to the second upper electrode through the second piezoelectric film are laminated through a second cavity.

Abstract: An acoustic wave filter includes: a substrate; resonators that are arranged on the substrate and excite acoustic waves; a ground terminal on the substrate; interconnection lines interconnecting the resonators and connecting predetermined ones of the resonators to the ground terminal; and a shield electrode disposed so as to be close to and face the interconnection lines.

Abstract: Distributed band reject filters are disclosed. A band reject filter includes a first acoustic resonator and a second acoustic resonator, each of which has either shunt resonators adapted to resonate substantially at respective resonance frequencies defining a rejection frequency band or series resonators adapted to anti-resonate substantially at respective anti-resonance frequencies defining the rejection frequency band. These resonators are connected through a phase shifter which imparts an impedance phase shift of approximately 45° to 135°. Exemplary applications of the band reject filters disclosed herein include implementation as an inter-stage band reject filter for a base station power amplifier for a wireless communication system, as a radio frequency band reject filter in a duplexer for a wireless communication terminal, and in a low noise amplifier input stage.

Abstract: An apparatus for providing impedance matching between a single-ended circuit and a differential circuit includes first and second capacitors and first and second inductors. The first capacitor is connected between an input/output of the single-ended circuit and a first differential input/output of the differential circuit. The first inductor is connected between the input/output of the single-ended circuit and a second differential input/output of the differential circuit. The second capacitor is connected between the second differential input/output of the differential circuit and ground. The second inductor is connected between the first differential input/output of the differential circuit and the second differential input/output of the differential circuit.

Abstract: Disclosed is a fabrication method for miniaturizing a film bulk acoustic wave resonator (FBAR) duplexer module including two FBAR filters, a tuning inductor, and a phase shifter. An exemplary embodiment of the present disclosure provides a method of miniaturizing a FBAR duplexer module, including forming a tuning inductor in a multilayer printed circuit board (PCB), forming a phase shifter in the multilayer PCB, and forming at least one of a transmitting FBAR filter and a receiving FBAR filter in the multilayer PCB.

Abstract: An acoustic wave device (5) includes a piezoelectric substrate (6) made of a lithium niobate material having the Euler angles (?, ?, ?), an electrode (7) disposed on the piezoelectric substrate (6) for exciting a major acoustic wave of a wavelength ?, and a protective layer (8) disposed on the piezoelectric substrate (6) to cover the electrode (7). The protective layer (8) has a thickness greater than 0.27?. The Euler angles satisfy ?100°????60°; 1.193??2°???1.193?+2°; and either ???2??3° or ?2?+3°??.

Abstract: A duplexer includes first and second acoustic filters and a phase shifter. The first acoustic filter is connected between an antenna and the transmitter, and has a first passband. The second acoustic filter is connected between the antenna and the receiver, and has a second passband. The phase shifter includes at least one series capacitor connected in series with the antenna and at least one shunt inductor connected between the at least one capacitor and ground. The phase shifter is connected between the antenna and the first filter when the first passband is higher than the second passband, and provides a negative phase shift of an output impedance of the first filter. The phase shifter is connected between the antenna and the second filter when the second passband is higher than the first passband, and provides a negative phase shift of an input impedance of the second filter.

Abstract: An elastic wave device includes a first elastic wave resonator and a second elastic wave resonator that are connected in series to each other, and a resistor is connected in parallel with the first elastic wave resonator while no resistors are connected in parallel with the second elastic wave resonator.

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.