A filter device according to an embodiment of the present disclosure includes a first filter and a second filter that are connected in parallel between a first terminal and a second terminal. The first filter includes multiple series arm resonators. The series arm resonators are disposed in series in a path from the first terminal via the first filter to the second terminal. The series arm resonators include a first series arm resonator and a second series arm resonator. Under a condition that a value obtained by dividing a difference between an antiresonance frequency and a resonance frequency of each series arm resonator by the resonance frequency is defined as a fractional bandwidth, a first fractional bandwidth of the first series arm resonator is different from a second fractional bandwidth of the second series arm resonator.

Disclosed is a radio frequency multiplexer having an M number of multiplexer branches each having an outer port terminal coupled to a common outer node, wherein M is a positive counting number. Each of the M number of multiplexer branches comprises a multi-bandpass filter configured to filter an N number of bands multiplexed by the radio frequency multiplexer to pass an individual group of N/M bands, wherein N is a positive counting number greater than one and equal to a total number of bands to be multiplexed. Each of the M number of multiplexer branches further includes an N/M number of resonator branches each having a band port terminal configured to pass a single band and an inner branch terminal coupled to an inner port terminal of the multi-bandpass filter at a common inner node.

Disclosed is a radio frequency multiplexer having an M number of multiplexer branches each having an outer port terminal coupled to a common outer node, wherein M is a positive counting number. Each of the M number of multiplexer branches comprises a multi-bandpass filter configured to filter an N number of bands multiplexed by the radio frequency multiplexer to pass an individual group of N/M bands, wherein N is a positive counting number greater than one and equal to a total number of bands to be multiplexed. Each of the M number of multiplexer branches further includes an N/M number of resonator branches each having a band port terminal configured to pass a single band and an inner branch terminal coupled to an inner port terminal of the multi-bandpass filter at a common inner node.

An acoustic wave device includes a common terminal, a first terminal, a second terminal, a first filter, a second filter, and an inductor. The first filter has a pass band corresponding to a relatively low frequency range and includes a surface acoustic wave filter using an SH wave. The second filter has a pass band corresponding to a relatively high frequency range. The first filter is between a branch point and the first terminal on a path connecting the common terminal and the first terminal. The second filter is between the branch point and the second terminal on a path connecting the common terminal and the second terminal. The inductor is on a path connecting the branch point and the first filter.

An acoustic wave device includes a common terminal, a first terminal, a second terminal, a first filter, a second filter, and an inductor. The first filter has a pass band corresponding to a relatively low frequency range and includes a surface acoustic wave filter using an SH wave. The second filter has a pass band corresponding to a relatively high frequency range. The first filter is between a branch point and the first terminal on a path connecting the common terminal and the first terminal. The second filter is between the branch point and the second terminal on a path connecting the common terminal and the second terminal. The inductor is on a path connecting the branch point and the first filter.

A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit is provided between a first terminal and a second terminal. Between the first terminal and the second terminal, the additional circuit is connected in parallel with at least a portion of the transmission filter circuit. The additional circuit includes an IDT electrode group including a plurality of IDT electrodes located next to each other in an acoustic wave propagation direction and two reflectors that sandwich the IDT electrode group and having different numbers of pairs of electrode fingers.

A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit is provided between a first terminal and a second terminal. Between the first terminal and the second terminal, the additional circuit is connected in parallel with at least a portion of the transmission filter circuit. The additional circuit includes an IDT electrode group including a plurality of IDT electrodes located next to each other in an acoustic wave propagation direction and two reflectors that sandwich the IDT electrode group and having different numbers of pairs of electrode fingers.

A radio frequency (RF) filter having a first passband and including a first circuit connected to a first node and a second node disposed on a path that connects a first terminal and a second terminal, and a second circuit connected to the first node and the second node. The first circuit includes a first filter having a second passband that includes a portion of a frequency range of the first passband and a bandwidth narrower than a bandwidth of the first passband. The second circuit includes a second filter having a third passband that includes a portion of a frequency range of the first passband and has a bandwidth narrower than the bandwidth of the first passband. The RF filter also includes a first phase shifter connected to a first terminal of the second filter; and a second phase shifter connected to a second terminal of the second filter.

A radio frequency (RF) filter having a first passband and including a first circuit connected to a first node and a second node disposed on a path that connects a first terminal and a second terminal, and a second circuit connected to the first node and the second node. The first circuit includes a first filter having a second passband that includes a portion of a frequency range of the first passband and a bandwidth narrower than a bandwidth of the first passband. The second circuit includes a second filter having a third passband that includes a portion of a frequency range of the first passband and has a bandwidth narrower than the bandwidth of the first passband. The RF filter also includes a first phase shifter connected to a first terminal of the second filter; and a second phase shifter connected to a second terminal of the second filter.

A surface acoustic wave device includes a piezoelectric substrate and functional elements on a first surface of the piezoelectric substrate. At least a portion of the functional elements includes an interdigital transducer (IDT) electrode, and a surface acoustic wave resonator is defined by the piezoelectric substrate and the IDT electrode. A portion of a wiring pattern connecting a first functional element and a second functional element is on a second surface different from the first surface of the piezoelectric substrate.