Abstract: An elastic wave filter has an unbalanced signal terminal, first and second balanced signal terminals, and first through fifth IDT electrodes arranged in ordinal order between a pair of grating reflectors. Wiring electrodes of the third and fifth IDT electrodes are disposed adjacent a ground electrode of the fourth IDT electrode, wiring electrodes of the second and third IDT electrodes are disposed adjacent one another, and ground electrodes of the first and second IDT electrodes are disposed adjacent one another. The unbalanced signal terminal is connected to the wiring electrodes of the first, third, and fifth IDT electrodes, and the first and second balanced signal terminals are connected to the wiring electrodes of the second and fourth IDT electrodes, respectively.

Abstract: A ladder-type surface acoustic wave filter assembly includes a plurality of series resonators formed on a substrate and connected between an input terminal and an output terminal. A first series resonator has a lowest resonance frequency among the plurality of series resonator. A parallel resonator formed on the substrate and connected between the plurality of series resonators and the ground terminal. A dielectric film is coupled to at least one of the plurality of series resonators and has an inverse temperature coefficient of frequency to that of the substrate. A film thickness of the dielectric film in a region where the second series resonator is formed is smaller than a film thickness of the dielectric film in a region where the first series resonator is formed.

Abstract: A high-frequency filter includes a first output to output a first signal, a first filter, a second filter, and a first matching circuit connected to an output of the first filter and to an output of the second filter. The first signal is provided to the first output from one of the output of the first filter and the output of the second filter via the first matching circuit. The first matching circuit includes a resonator connected in series between the first output and the output of only one of the first filter and the second filter.

Abstract: An electronic device includes a main circuit connected between an input terminal and an output terminal, and an auxiliary circuit connected in parallel to the main circuit between the input terminal and the output terminal. The main circuit includes a filter having a first passband and a stopband. The auxiliary circuit has a passing characteristic that allows a signal having a frequency in a certain frequency band inside the stopband to pass through the auxiliary circuit. The main circuit is configured to output a main signal in response to an input signal. The auxiliary circuit is configured to output an auxiliary signal in response to the input signal. The main signal and the auxiliary signal contain phase components opposite to each other in the certain frequency band inside the stopband. This electronic device has an attenuation amount in the stopband.

Abstract: A ladder-type surface acoustic wave filter includes a first series resonator having the lowest resonance frequency among a plurality of series resonators; and a second series resonator having a resonance frequency higher than the first series resonator. The film thickness of a dielectric film in the region where the first series resonator is formed is larger than that of a dielectric film in the region where the second series resonator is formed.

Abstract: An elastic wave filter includes first and second longitudinally coupled elastic wave filters. The first filter includes a first pair of grating reflectors, first to fifth IDT electrodes arranged in ordinal order between the grating reflectors along a propagation direction of elastic waves, a first unbalanced terminal, and first and second balanced terminals. The second filter has a second unbalanced terminal, and third and fourth balanced terminals, the first and second unbalanced terminals being electrically connected to each other, the first and third balanced terminals being electrically connected to a first JO terminal, and the second and fourth balanced terminals being electrically connected to a second JO terminal. The first and second balanced terminals, and the third and fourth balanced terminals, output signals opposite in phase to each other. A first signal at the first JO terminal is opposite in phase to a second signal at the second IO terminal.

Abstract: An elastic wave device includes an interdigital transducer (IDT) electrode in contact with a piezoelectric substrate having a bus bar electrode region including one of a first bus bar electrode and a second bus bar electrode of the IDT electrode, an alternately disposed region where first electrode fingers are alternately disposed with second electrode fingers of the IDT electrode, and an intermediate region including one of the first electrode fingers and the second electrode fingers. A dielectric film is formed in at least part of the intermediate region and in contact with an upper surface of the IDT electrode. The dielectric film includes a medium in which an acoustic velocity of a transverse wave propagating in the dielectric film is lower than an acoustic velocity of a main elastic wave of the alternately disposed region. The dielectric film is not formed in the alternately disposed region.

Abstract: Assigning multiple functions to a PA and simplifying wiring and circuits are achieved without using switches in a transmission-and-reception system using a high-frequency filter that supports multiple bands. Provided is a high-frequency filter including: first and second transmission filters; first and second reception filters; and a matching circuit connected to input sides of the first and second transmission filters. Transmission signals are inputted to the first and second transmission filters via the matching circuit. A resonator forming the matching circuit is serially connected to an input side of, among the first and second transmission filters, a filter whose passband is a higher frequency band.

Abstract: An elastic wave element includes a piezoelectric substrate, an IDT electrode, and a first dielectric film. The IDT electrode includes a first bus bar electrode, a second bus bar electrode, first electrode fingers, and second electrode fingers. The piezoelectric substrate includes a bus bar electrode region, an alternately disposed region, and an intermediate region. The first dielectric film is formed in at least a part of the intermediate region, and formed of a medium in which acoustic velocity of a transverse wave propagating in the first dielectric film is lower than acoustic velocity of a main elastic wave in the alternately disposed region.

Abstract: In an acoustic wave device, an unnecessary high-order transverse mode wave is suppressed. The acoustic wave device includes a piezoelectric substrate, at least one pair of interdigital transducer (IDT) electrodes formed on the piezoelectric substrate, and a dielectric film which covers at least a part of the piezoelectric substrate and the IDT electrodes. The IDT electrodes each have a plurality of electrode fingers interleaved with each other. An acoustic velocity of an acoustic wave in the area in which the electrode fingers are interleaved with each other is greater than an acoustic velocity of an acoustic wave in an edge area including end portions of the electrode fingers.

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: 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: In an acoustic wave device, a high-order transverse mode wave which is an unnecessary wave is suppressed. The acoustic wave device includes: a piezoelectric substrate; at least one pair of IDT electrodes formed on the piezoelectric substrate; and a dielectric film which covers at least a part of the piezoelectric substrate and the IDT electrodes, and the IDT electrodes each has a plurality of electrode fingers. The dielectric film covers at least an area in which the electrode fingers are arranged interleaved with each other. An acoustic velocity of an acoustic wave in an intersection area, within the region, which is a portion from ends of the electrode fingers to a predetermined length or more inward from the ends, is greater than an acoustic velocity of an acoustic wave in an edge area including end portions of the electrode fingers.

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: Assigning multiple functions to a PA and simplifying wiring and circuits are achieved without using switches in a transmission-and-reception system using a high-frequency filter that supports multiple bands. Provided is a high-frequency filter including: first and second transmission filters; first and second reception filters; and a matching circuit connected to input sides of the first and second transmission filters. Transmission signals are inputted to the first and second transmission filters via the matching circuit. A resonator forming the matching circuit is serially connected to an input side of, among the first and second transmission filters, a filter whose passband is a higher frequency band.

Abstract: In a ladder-type elastic wave filter, a resonance frequency of a second parallel resonator is higher than that of a series resonator and lower than an antiresonance frequency of a series resonator. With this configuration, an attenuation pole is formed by the second parallel resonator at a frequency region lower than an attenuation pole formed by the series resonator in a frequency region higher than the passband of the ladder-type elastic wave filter.

Abstract: An electronic device includes a main circuit connected between an input terminal and an output terminal, and an auxiliary circuit connected in parallel to the main circuit between the input terminal and the output terminal. The main circuit includes a filter having a first passband and a stopband. The auxiliary circuit has a passing characteristic that allows a signal having a frequency in a certain frequency band inside the stopband to pass through the auxiliary circuit. The main circuit is configured to output a main signal in response to an input signal. The auxiliary circuit is configured to output an auxiliary signal in response to the input signal. The main signal and the auxiliary signal contain phase components opposite to each other in the certain frequency band inside the stopband. This electronic device has an attenuation amount in the stopband.

Abstract: An acoustic wave resonator includes a piezoelectric body, an IDT electrode for exciting an acoustic wave with wavelength ?, and a dielectric thin film provided so as to cover the IDT electrode. The IDT electrode includes a bus bar electrode region, a dummy electrode region, and an IDT cross region in order from outside. The film thickness of the dielectric thin film above at least one of the bus bar electrode region and the dummy electrode region is smaller than that above the IDT cross region by 0.1? to 0.25?. This configuration provides an acoustic wave resonator that reduces transverse-mode spurious emission.

Abstract: A ladder-type filter having plural elastic-wave resonators provided on a series arm and a parallel arm in a ladder shape on a piezoelectric substrate. Each of the elastic-wave resonators has an interdigital electrode. The interdigital electrode has plural electrode finger pairs formed of electrode fingers extending from first and second bus bars. The interdigital electrode included in the elastic-wave resonator provided on the parallel arm has an electrode cross width of the electrode fingers extending from the first and second bus bars 23 times or more of the wavelength of elastic waves excited by the interdigital electrodes.

Abstract: A multimode elastic wave device includes a pair of reflectors, and a first interdigital transducer (IDT) electrode through a fifth IDT electrode arranged between the pair of reflectors. In this configuration, each of the average of electrode-finger pitches in the first IDT electrode and the average of electrode-finger pitches in the fifth IDT electrode is smaller than both of the average of electrode-finger pitches in the second IDT electrode and the average of electrode-finger pitches in the fourth IDT electrode.