Abstract: A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.

Abstract: A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.

Abstract: An acoustic wave filter device includes a longitudinally coupled resonator acoustic wave filter on a series arm that connects an input terminal and an output terminal, first and second parallel arm resonators on first and second parallel arms that connect the series arm and a ground potential, an input-side ground port of the longitudinally coupled resonator acoustic wave filter and a ground port of at least one of the first and second parallel arm resonators are connected in common, an output-side ground port of the longitudinally coupled resonator acoustic wave filter and a ground port of at least another of the first and second parallel arm resonators are connected in common, and an electrostatic capacitance of the first parallel arm resonator is different from an electrostatic capacitance of the second parallel arm resonator.

Abstract: A composite filter device includes a piezoelectric substrate made of LiNbO3, a first filter on the piezoelectric substrate, and including acoustic wave resonators, and a second filter including one end connected in common to one end of the first filter, wherein a pass band of the second filter is in a frequency band higher than a pass band of the first filter, and bulk wave radiation frequencies of all of the first and second resonators of the first filter are higher than the pass band of the second filter.

Abstract: A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit defines a first signal path connecting a first terminal and a second terminal. The additional circuit is connected to a first node located between the first terminal and the transmission filter circuit on the first signal path and a second node located between the second terminal and the transmission filter circuit on the first signal path and defines a second signal path connecting the first node and the second node. The additional circuit includes, on the second signal path, a resonator group, a capacitive element, and an inductance element. The inductance element is electromagnetically coupled to the transmission filter circuit.

Abstract: A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit defines a first signal path connecting a first terminal and a second terminal. The additional circuit is connected to a first node located between the first terminal and the transmission filter circuit on the first signal path and a second node located between the second terminal and the transmission filter circuit on the first signal path and defines a second signal path connecting the first node and the second node. The additional circuit includes, on the second signal path, a resonator group, a capacitive element, and an inductance element. The inductance element is electromagnetically coupled to the transmission filter circuit.

Abstract: A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.

Abstract: An acoustic wave filter device includes a longitudinally coupled resonator acoustic wave filter on a series arm that connects an input terminal and an output terminal, first and second parallel arm resonators on first and second parallel arms that connect the series arm and a ground potential, an input-side ground port of the longitudinally coupled resonator acoustic wave filter and a ground port of at least one of the first and second parallel arm resonators are connected in common, an output-side ground port of the longitudinally coupled resonator acoustic wave filter and a ground port of at least another of the first and second parallel arm resonators are connected in common, and an electrostatic capacitance of the first parallel arm resonator is different from an electrostatic capacitance of the second parallel arm resonator

Abstract: An elastic wave filter includes a piezoelectric substrate, an IDT electrode provided on the piezoelectric substrate, a first shield electrode provided on the piezoelectric substrate, a first insulating film laminated on the piezoelectric substrate and extending onto the first shield electrode, a first signal terminal provided on the first insulating film, a second signal terminal provided on the piezoelectric substrate, and a first ground terminal provided on the piezoelectric substrate and connected to a ground potential. The first shield electrode is not electrically connected to the IDT electrode and the first and second signal terminals. The first signal terminal is included in the first shield electrode when seen from above. One of the first signal terminal and the second signal terminal is an output terminal and the other thereof is an input terminal.

Abstract: An elastic wave filter includes a piezoelectric substrate, an IDT electrode provided on the piezoelectric substrate, a first shield electrode provided on the piezoelectric substrate, a first insulating film laminated on the piezoelectric substrate and extending onto the first shield electrode, a first signal terminal provided on the first insulating film, a second signal terminal provided on the piezoelectric substrate, and a first ground terminal provided on the piezoelectric substrate and connected to a ground potential. The first shield electrode is not electrically connected to the IDT electrode and the first and second signal terminals. The first signal terminal is included in the first shield electrode when seen from above. One of the first signal terminal and the second signal terminal is an output terminal and the other thereof is an input terminal.