Filter devices and fabrication methods are disclosed. A filter device includes a piezoelectric plate and a conductor pattern on a front surface of the piezoelectric plate. The conductor pattern includes interdigital transducers (IDTs) of a plurality of transversely-excited film bulk acoustic resonators (XBARs) and a plurality of conductors connecting the plurality of XBARs in a ladder filter circuit architecture. The plurality of conductors includes a first conductor adjacent to a second conductor. An opening is provided through the piezoelectric plate between the first conductor and the second conductor.

Filter devices and fabrication methods are disclosed. A filter device includes a piezoelectric plate and a conductor pattern on a front surface of the piezoelectric plate. The conductor pattern includes interdigital transducers (IDTs) of a plurality of transversely-excited film bulk acoustic resonators (XBARs) and a plurality of conductors connecting the plurality of XBARs in a ladder filter circuit architecture. The plurality of conductors includes a first conductor adjacent to a second conductor. An opening is provided through the piezoelectric plate between the first conductor and the second conductor.

An acoustic structure is provided. The acoustic structure includes an acoustic resonator structure configured to resonate in a series resonance frequency (e.g., passband frequency) to pass a signal, or cause a series capacitance to block the signal in a parallel resonance frequency (e.g., stopband frequency). The parallel resonance frequency may become higher than the series resonance frequency when the tunable capacitance is lesser than or equal to two times of the series capacitance (C.sub.Tune≤2C.sub.0), or lower than the series resonance frequency when the tunable capacitance is greater than two times of the series capacitance (C.sub.Tune>2C.sub.0). In this regard, the acoustic structure can be configured to include a tunable reactive circuit to generate the tunable capacitance (C.sub.Tune) to adjust the parallel resonance frequency. As such, it may be possible to flexibly configure the acoustic resonator structure to block the signal in desired stopband frequencies.

An acoustic structure is provided. The acoustic structure includes an acoustic resonator structure configured to resonate in a series resonance frequency (e.g., passband frequency) to pass a signal, or cause a series capacitance to block the signal in a parallel resonance frequency (e.g., stopband frequency). The parallel resonance frequency may become higher than the series resonance frequency when the tunable capacitance is lesser than or equal to two times of the series capacitance (C.sub.Tune≤2C.sub.0), or lower than the series resonance frequency when the tunable capacitance is greater than two times of the series capacitance (C.sub.Tune>2C.sub.0). In this regard, the acoustic structure can be configured to include a tunable reactive circuit to generate the tunable capacitance (C.sub.Tune) to adjust the parallel resonance frequency. As such, it may be possible to flexibly configure the acoustic resonator structure to block the signal in desired stopband frequencies.

Modern RF front end filters feature acoustic resonators in a film bulk acoustic resonator (FBAR) structure. An acoustic filter is a circuit that includes at least (and typically significantly more) two resonators. The acoustic resonator structure comprises a substrate including sidewalls and a vertical cavity between the sidewalls and two or more resonators deposited in the vertical cavity.

Modern RF front end filters feature acoustic resonators in a film bulk acoustic resonator (FBAR) structure. An acoustic filter is a circuit that includes at least (and typically significantly more) two resonators. The acoustic resonator structure comprises a substrate including sidewalls and a vertical cavity between the sidewalls and two or more resonators deposited in the vertical cavity.

An acoustic wave device includes a piezoelectric layer that is made of lithium niobate or lithium tantalate, and a plurality of pairs of electrodes opposed to each other in a direction intersecting with a thickness direction of the piezoelectric layer, in which a bulk wave in a thickness shear primary mode is used or d/p is about 0.5 or lower when a thickness of the piezoelectric layer is d and a distance between centers of mutually adjacent electrodes among the plurality of pairs of electrodes is p. The plurality of pairs of electrodes include at least one pair of first electrodes of a first acoustic wave resonator and at least one pair of second electrodes of a second acoustic wave resonator. A direction orthogonal to a longitudinal direction of the second electrodes in the second acoustic wave resonator is inclined at an angle that is greater than 0° and smaller than 360° with respect to a direction orthogonal to a longitudinal direction of the first electrodes in the first acoustic wave resonator.

An acoustic wave device includes a piezoelectric layer, first and second upper electrodes, first and second lower electrodes, and first and second acoustic reflection films. In plan view, first and second resonator portions are respectively defined by portions where the first upper electrode and the first lower electrode overlap and where the second upper electrode and the second lower electrode overlap. The first and second acoustic reflection films respectively include first and second metal layers. First and second overlapping portions are respectively defined by portions where only the first upper electrode overlaps with the first metal layer and where only the second upper electrode overlaps with the second metal layer. An area of the first resonator portion is smaller than an area of the second resonator portion and an area of the first overlapping portion is larger than an area of the second overlapping portion.

A filter module for multiple carrier aggregation is provided which includes: a substrate having a first side and a second side, a plurality of filters disposed on the first side, a plurality of signal terminals disposed on the second side, each selectively connected to at least one of the plurality of filters and a ground plane disposed on the second side, wherein the ground plane is arranged to substantially surround each signal terminal on the second side and a method of improving cross isolation in a multiple carrier aggregation filter module, where the filter module includes a plurality of filters disposed on a first side of a substrate and a plurality of signal terminals on a second side of a substrate, and where the method includes disposing a ground plane on the second side wherein the ground plane is arranged to substantially surround each signal terminal on the second side.

A filter module for multiple carrier aggregation is provided which includes: a substrate having a first side and a second side, a plurality of filters disposed on the first side, a plurality of signal terminals disposed on the second side, each selectively connected to at least one of the plurality of filters and a ground plane disposed on the second side, wherein the ground plane is arranged to substantially surround each signal terminal on the second side and a method of improving cross isolation in a multiple carrier aggregation filter module, where the filter module includes a plurality of filters disposed on a first side of a substrate and a plurality of signal terminals on a second side of a substrate, and where the method includes disposing a ground plane on the second side wherein the ground plane is arranged to substantially surround each signal terminal on the second side.