A composite filter device includes bandpass filters whose respective one ends are electrically connected in common. A first bandpass filter of the bandpass filters includes a first filter, a switch, a second filter, and an impedance element that is electrically connected to the switch and having an impedance value larger than the input impedance value of the second filter. The switch is configured to be switched between a first state in which the first filter and the second filter are electrically connected and a second state in which the first filter and the impedance element are electrically connected.

A composite filter device includes bandpass filters whose respective one ends are electrically connected in common. A first bandpass filter of the bandpass filters includes a first filter, a switch, a second filter, and an impedance element that is electrically connected to the switch and having an impedance value larger than the input impedance value of the second filter. The switch is configured to be switched between a first state in which the first filter and the second filter are electrically connected and a second state in which the first filter and the impedance element are electrically connected.

Guided Surface Acoustic Wave (SAW) devices with improved quartz orientations are disclosed. A guided SAW device includes a quartz carrier substrate, a piezoelectric layer on a surface of the quartz carrier substrate, and at least one interdigitated transducer on a surface of the piezoelectric layer opposite the quartz carrier substrate. The quartz carrier substrate includes an orientation that provides improved performance parameters for the SAW device, including electromechanical coupling factor, resonator quality factor, temperature coefficient of frequency, and delta temperature coefficient of frequency.

An elastic wave device includes an elastic wave element including a piezoelectric substrate with a first main surface and a second main surface that face each other, an IDT electrode disposed on the second main surface of the piezoelectric substrate, a support disposed on the second main surface of the piezoelectric substrate so as to surround the IDT electrode in plan view, and a cover that is disposed on the support and seals the IDT electrode together with the support and the piezoelectric substrate, a mounting substrate above which the elastic wave element is mounted, and a sealing resin that is disposed on the side of the side of the upper surface of the mounting substrate and seals the elastic wave element. A thickness of the mounting substrate is less than a thickness of the sealing resin that corresponds to a distance from a surface of the sealing resin in contact with the upper surface of the mounting substrate to a surface of the sealing resin on an opposite side of the mounting substrate.

A packaged acoustic wave filter component can include an acoustic wave device including a first piezoelectric layer and an interdigital transducer electrode on the first piezoelectric layer. A support layer may be included over the acoustic wave device, and the packaged hybrid filter component can also include a bulk acoustic wave resonator over the support layer. A cap layer may extend over and encapsulate the bulk acoustic wave resonator. One or more external vias may extend through the support layer and the underlying layers of the acoustic wave device to provide electrical communication with the packaged bulk acoustic wave generator.

An acoustic wave filter component can include a surface acoustic wave device including a first piezoelectric layer, an interdigital transducer electrode on the first piezoelectric layer, and an additional layer, such as a temperature compensation layer, over the interdigital transducer electrode. The acoustic wave filter component can also include a bulk acoustic wave resonator supported by the additional layer. The additional layer may be a layer on which a surface acoustic wave of the surface acoustic wave device will propagate. The bulk acoustic wave resonator may include an air cavity, where a shape of the air cavity is defined in part by the additional layer.

An acoustic wave filter component can include an acoustic wave device including a multi-layer piezoelectric substrate. The multi-layer piezoelectric substrate can include at least a support substrate and a piezoelectric layer. The acoustic wave device can include an interdigital transducer electrode on the piezoelectric layer. An additional layer can be located over the interdigital transducer electrode. The acoustic wave filter component can also include a bulk acoustic wave resonator supported by the additional layer. The acoustic wave device can be a boundary wave resonator, and one or more boundary wave resonators may be provided in a stacked arrangement, with the bulk acoustic wave resonator in the top layer of the stacked arrangement. The acoustic wave device can also be a temperature-compensated surface acoustic wave device.

Energy confinement in acoustic wave devices. In some embodiments, a surface acoustic wave device can include a quartz substrate, a piezoelectric film formed from LiTaO.sub.3 or LiNbO.sub.3 and disposed over the quartz substrate, and an interdigital transducer electrode formed over the piezoelectric film. The surface acoustic wave device can further include a bonding layer implemented over the piezoelectric film, and a cap layer formed over the bonding layer to thereby substantially confine energy of a propagating wave below the cap layer.

A device wafer with functional device structures, comprises a semiconductor substrate (SU) as a carrier wafer, a piezoelectric layer (PL) arranged on the carrier wafer and functional device structures (DS) of a first and a second type realized by a structured metallization on top of the piezoelectric layer (PL). A space charge region is formed near the top surface of the carrier wafer to yield enhanced electrical isolation between functional device structures (DS) of first and second type.

In a method of manufacturing a piezoelectric device in which a piezoelectric thin film on which functional conductors are formed is fixed to a support substrate by a fixing layer, an alignment mark is formed on one main surface of a light-transmitting piezoelectric substrate. A sacrificial layer is formed on a main surface of the piezoelectric substrate with reference to the alignment mark and the fixing layer is formed so as to cover the sacrificial layer and is bonded to the support substrate. The piezoelectric thin film is formed by being separated from the piezoelectric substrate and the functional conductors are formed on the surface of the piezoelectric thin film with reference to the alignment mark. The piezoelectric device is able to be manufactured while positions of formation regions of conductors are adjusted efficiently.