A piezoelectric device includes a support substrate, an intermediate layer on the support substrate, a piezoelectric layer on the intermediate layer, a functional element on the piezoelectric layer, an insulation layer, and a wiring electrode. The insulation layer is on the support substrate and in contact with the intermediate layer and the piezoelectric layer. The wiring electrode extends from a top of the insulation layer to a top of the piezoelectric layer and is connected to the functional element. The insulation layer includes first and second regions. The first region is thinner than a thickness of the multilayer body. The second region connects the first region and the multilayer body, and includes a portion slanted from the first region toward an upper surface of the piezoelectric layer. The second region of the insulation layer does not extend to the top of the piezoelectric layer.

Embodiments of the invention relate to a surface acoustic wave device including a piezoelectric substrate, an interdigital transducer electrode on the piezoelectric substrate and a first thermally conductive layer arranged over the piezoelectric substrate and interdigital transducer electrode. The first thermally conductive layer is spaced apart from the piezoelectric substrate and interdigital transducer electrode. The surface acoustic wave device also includes a second thermally conductive layer configured to dissipate heat generated by the surface acoustic wave device. The second thermally conductive layer is arranged on an opposing side of the piezoelectric substrate to the interdigital transducer electrode. Related wafer-level packages, radio frequency modules and wireless communication devices are also provided.

Embodiments of the invention relate to a surface acoustic wave device including a piezoelectric substrate, an interdigital transducer electrode on the piezoelectric substrate and a first thermally conductive layer arranged over the piezoelectric substrate and interdigital transducer electrode. The first thermally conductive layer is spaced apart from the piezoelectric substrate and interdigital transducer electrode. The surface acoustic wave device also includes a second thermally conductive layer configured to dissipate heat generated by the surface acoustic wave device. The second thermally conductive layer is arranged on an opposing side of the piezoelectric substrate to the interdigital transducer electrode. Related wafer-level packages, radio frequency modules and wireless communication devices are also provided.

A surface acoustic wave resonator comprises a multi-layer piezoelectric substrate including a carrier substrate, a layer of a first dielectric material disposed on a front side of the carrier substrate, and a layer of piezoelectric material disposed on a front side of the layer of the first dielectric material, the piezoelectric material having a cut angle θ of from about 12 degrees to about 25 degrees to suppress bulk leakage and improve gamma, and interdigital transducer electrodes disposed on a front side of the layer of piezoelectric material.

A multiplexer includes a first filter and a second filter with a lower pass band than that of the first filter. A longitudinally coupled acoustic wave resonator of the first filter includes an interdigital transducer electrode group of interdigital transducer electrodes having an asymmetric shape with respect to a center line that passes through a center of the interdigital transducer electrode group and is perpendicular or substantially perpendicular to an acoustic wave propagation direction. The interdigital transducer electrodes connected to a first path on a common terminal side when seen from the longitudinally coupled acoustic wave resonator have a smaller aggregate average of electrode finger pitches of the interdigital transducer electrodes and a smaller sum of numbers of pairs of electrode fingers of the interdigital transducer electrodes, compared with the interdigital transducer electrodes connected to the first path on a first terminal side.

A multiplexer includes a first filter and a second filter with a lower pass band than that of the first filter. A longitudinally coupled acoustic wave resonator of the first filter includes an interdigital transducer electrode group of interdigital transducer electrodes having an asymmetric shape with respect to a center line that passes through a center of the interdigital transducer electrode group and is perpendicular or substantially perpendicular to an acoustic wave propagation direction. The interdigital transducer electrodes connected to a first path on a common terminal side when seen from the longitudinally coupled acoustic wave resonator have a smaller aggregate average of electrode finger pitches of the interdigital transducer electrodes and a smaller sum of numbers of pairs of electrode fingers of the interdigital transducer electrodes, compared with the interdigital transducer electrodes connected to the first path on a first terminal side.

A filter circuit comprises in a signal line a band filter (BF) allowing to let pass a useful frequency band and a notch filter (NF) circuited in series to the band filter for filtering out a stop band frequency. The notch filter comprises a series circuit of a number of parallel shunt elements (SE1 . . . SE6) wherein each shunt element is shifted infrequency against the other shunt elements that the frequencies thereof are distributed (f1 . . . F6) over a notch band. All shunt elements may be realized as a SAW one-port resonator (TR.sub.NF) including regions with different pitches.

A filter circuit comprises in a signal line a band filter (BF) allowing to let pass a useful frequency band and a notch filter (NF) circuited in series to the band filter for filtering out a stop band frequency. The notch filter comprises a series circuit of a number of parallel shunt elements (SE1 . . . SE6) wherein each shunt element is shifted infrequency against the other shunt elements that the frequencies thereof are distributed (f1 . . . F6) over a notch band. All shunt elements may be realized as a SAW one-port resonator (TR.sub.NF) including regions with different pitches.

Aspects of this disclosure relate to an acoustic wave filter that includes acoustic wave resonators arranged to filter a radio frequency signal. The acoustic wave resonators include a first acoustic wave resonator. The acoustic wave filter includes a circuit element in parallel with the first acoustic wave resonator in a stage of the acoustic wave filter. The circuit element and the first acoustic wave resonator have different resonant frequencies. The circuit element can reduce an impact of bulk mode of the first acoustic wave resonator on insertion loss of the acoustic wave filter. The first acoustic wave resonator can be a surface acoustic wave resonator in certain embodiments. The circuit element can be a second acoustic wave resonator or a capacitor, for example.

Aspects of this disclosure relate to an acoustic wave filter that includes acoustic wave resonators arranged to filter a radio frequency signal. The acoustic wave resonators include a first acoustic wave resonator. The acoustic wave filter includes a circuit element in parallel with the first acoustic wave resonator in a stage of the acoustic wave filter. The circuit element and the first acoustic wave resonator have different resonant frequencies. The circuit element can reduce an impact of bulk mode of the first acoustic wave resonator on insertion loss of the acoustic wave filter. The first acoustic wave resonator can be a surface acoustic wave resonator in certain embodiments. The circuit element can be a second acoustic wave resonator or a capacitor, for example.