Abstract:
In a representative embodiment, a bulk acoustic wave (BAW) resonator, comprises: a first electrode disposed over a substrate; a first piezoelectric layer disposed over the first electrode, the first piezoelectric layer having a first c-axis oriented along a first direction; a second electrode disposed over the first piezoelectric layer; and a second piezoelectric layer disposed over the first electrode and adjacent to the first piezoelectric layer, wherein the second piezoelectric layer has a second c-axis oriented in a second direction that is substantially antiparallel to the first direction.
Abstract:
Method for fabricating an acoustical resonator on a substrate having a top surface. First, a depression in said top surface is generated. Next, the depression is filled with a sacrificial material. The filled depression has an upper surface level with said top surface of said substrate. Next, a first electrode is deposited on said upper surface. Then, a layer of piezoelectric material is deposited on said first electrode. A second electrode is deposited on the layer of piezoelectric material using a mass load lift-off process.
Abstract:
A microfabricated device has a first substrate, a second substrate, a film bulk acoustic resonator (FBAR) device, and a circuit. The second substrate is bonded to the first substrate to define a chamber. The FBAR device is located on a surface of the first substrate and inside the chamber. The circuit is located on a surface of the second substrate and inside the chamber. An electrical connection connects the circuit and the FBAR device.
Abstract:
An apparatus and method for measuring a target environmental variable (TEV) that employs a film-bulk acoustic resonator with motion plate. The film-bulk acoustic resonator (FBAR) includes an acoustic reflector formed in an FBAR wafer and a surface. A first electrode is formed on the surface of the acoustic reflector and has a surface. A piezoelectric layer is formed on the surface of the first electrode and has a surface. A second electrode is formed on the surface of the piezoelectric layer. A motion plate is suspended in space at a predetermined distance relative to the surface of the second electrode and is capacitively coupled to the FBAR.
Abstract:
Embodiments of the acoustic galvanic isolator comprise a carrier signal source, a modulator connected to receive an information signal and the carrier signal, a demodulator, and, connected between the modulator and the demodulator, an electrically-isolating acoustic coupler comprising an electrically-isolating film acoustically-coupled transformer (FACT).
Abstract:
The temperature-compensated film bulk acoustic resonator (FBAR) device comprises an FBAR stack. The FBAR stack comprises an FBAR and a temperature-compensating element. The FBAR is characterized by a resonant frequency having a temperature coefficient, and comprises opposed planar electrodes and a piezoelectric element between the electrodes. The piezoelectric element has a temperature coefficient on which the temperature coefficient of the resonant frequency depends at least in part. The temperature-compensating element has a temperature coefficient opposite in sign to the temperature coefficient of the piezoelectric element.
Abstract:
Embodiments of an acoustically-coupled transformer have a first stacked bulk acoustic resonator (SBAR) and a second SBAR. Each of the SBARs has a lower film bulk acoustic resonator (FBAR) and an upper FBAR, and an acoustic decoupler between the FBARs. The upper FBAR is stacked atop the lower FBAR. Each FBAR has opposed planar electrodes and a piezoelectric element between the electrodes. The piezoelectric element is characterized by a c-axis. The c-axes of the piezoelectric elements of the lower FBARs are opposite in direction, and the c-axes of the piezoelectric elements of the upper FBARs are opposite in direction. The transformer additionally has a first electrical circuit connecting the lower FBAR of the first SBAR to the lower FBAR of the second SBAR, and a second electrical circuit connecting the upper FBAR of the first SBAR to the upper FBARs of the second SBAR.
Abstract:
The encapsulated film bulk acoustic resonator (FBAR) device comprises a substrate, an FBAR stack over the substrate, an element for acoustically isolating the FBAR stack from the substrate, encapsulant covering the FBAR stack, and an acoustic Bragg reflector between the top surface of the FBAR stack and the encapsulant. The FBAR stack comprises an FBAR and has a top surface remote from the substrate. The FBAR comprises opposed planar electrodes and a piezoelectric element between the electrodes. The acoustic Bragg reflector comprises a metal Bragg layer and a plastic Bragg layer juxtaposed with the metal Bragg layer. The large ratio between the acoustic impedances of the metal of the metal Bragg layer and the plastic material of the plastic Bragg layer enables the acoustic Bragg reflector to provide sufficient acoustic isolation between the FBAR and the encapsulant for the frequency response of the FBAR device to exhibit minor, if any, spurious artifacts arising from undesirable acoustic coupling between the FBAR and the encapsulant.
Abstract:
A sensor senses an environmental condition. The sensor includes a film bulk acoustic resonator that includes a layer of material that causes resonant frequency and/or quality factor shifts of the film bulk acoustic resonator in response to changes in the environmental condition. The environmental condition may be relative humidity and the layer of material may be a moisture absorptive material.
Abstract:
An apparatus including vertically separated acoustic resonators are disclosed. The apparatus includes a first acoustic resonator on a substrate and a second acoustic resonator vertically separated above the first acoustic resonator. Because the resonators are vertically separated above another, total area required to implement the resonators is reduced thereby savings in die size and cost are realized. The vertically separated resonators are supported by standoffs that are fabricated on the substrate, or on a resonator.