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.

An extractor includes a band elimination filter that is connected between a common terminal and a first input-output terminal and that has a stop band equal or substantially equal to a first frequency band, and a band pass filter that is connected between the common terminal and a second input-output terminal and that has a pass band equal or substantially equal to a second frequency band that overlaps the first frequency band. The band pass filter includes, series arm resonators, three or more parallel arm resonators, and three or more inductors that are connected between the ground and the parallel arm resonators. The L value of a first inductor that is connected and nearest to the common terminal is smaller than the L value of a third inductor, and the L value of a second inductor that is connected and second-nearest to the common terminal is smaller than the L value of the third inductor.

A multiplexer includes first and second nodes, an inductor, a first transmit/receive filter, and second and third transmit filters. The inductor is connected at one end to the first node and at the other end to the second node. The first transmit/receive filter is connected to the first node without the inductor interposed therebetween and uses the transmit and receive bands of band A as a pass band. The second transmit filter is connected to the second node and uses the transmit band of band B as a pass band. The third transmit filter is connected to the second node and uses the transmit band of band C as a pass band.

Aspects of this disclosure relate to a multiplexer that includes an acoustic wave filter including acoustic wave resonators on at least two die with a transmission line electrically connecting the acoustic wave resonators on the two die. The acoustic wave filter can include a plurality of acoustic wave resonators on a first die electrically connected to at least one acoustic wave resonator on a second die via the transmission line. The acoustic wave resonator on the second die can provide a relatively high impedance at a respective passband of one or more other filters of the multiplexer. This can reduce effects of the transmission line of the acoustic wave filter on a respective passband of one or more other filters of the multiplexer.

Aspects of this disclosure relate to acoustic wave filters that include different types of acoustic wave resonators for series resonators and shunt resonators. In certain embodiments, an acoustic wave filter includes series temperature compensated surface acoustic wave resonators and shunt bulk acoustic wave resonators. Such an acoustic wave filter can be a band pass filter.

Aspects of this disclosure relate to acoustic wave filters that include different types of acoustic wave resonators for series resonators and shunt resonators. In certain embodiments, an acoustic filter component includes a first die including surface acoustic wave resonators and a second die including bulk acoustic wave resonators. An interdigital transducer electrode of a surface acoustic wave resonator can be a side of the first die. An electrode of a bulk acoustic wave resonator can be on a side of the second die facing the side of the first die with the interdigital transducer electrode thereon. An acoustic wave filter can include series resonators on one of the first and second die and shunt resonators on the other of the first and second die.

An integrated radio frequency (RF) circuit combines complementary features of passive devices and acoustic filters and includes a first die, a second die, and a third die. The first die includes a substrate having one or more passive devices. The second die includes a first acoustic filter. The second die is stacked and coupled to a first surface of the first die. The third die includes a second acoustic filter. The third die is stacked and coupled to a second surface opposite the first surface of the first die.

Aspects of this disclosure relate to a multiplexer that includes an acoustic wave filter including acoustic wave resonators on at least two die with a transmission line electrically connecting the acoustic wave resonators on the two die. The acoustic wave filter can include a plurality of acoustic wave resonators on a first die electrically connected to at least one acoustic wave resonator on a second die via the transmission line. The acoustic wave resonator on the second die can provide a relatively high impedance at a respective passband of one or more other filters of the multiplexer. This can reduce effects of the transmission line of the acoustic wave filter on a respective passband of one or more other filters of the multiplexer.

A tunable filter with wide tuning range and high out-of-band rejection is achieved with a tunable bandpass filter and a number of cascaded, fixed frequency Lame-Mode Resonators (LMRs) notch filters or other resonators. In some embodiments, the filter can be implemented with all of the elements on an integrated circuit, saving space for use in applications such as mobile phones or other mobile communication devices.

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.