Techniques for improving Bulk Acoustic Wave (BAW) reflector and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. A Bulk Acoustic Wave (BAW) resonator of this disclosure may comprise a substrate and an active piezoelectric resonant volume. The active piezoelectric resonant volume of the Bulk Acoustic Wave (BAW) resonator may have a main resonant frequency. The active piezoelectric resonant volume of the Bulk Acoustic Wave (BAW) resonator may comprise first and second piezoelectric layers having respective piezoelectric axis that substantially oppose one another. A first patterned layer may be disposed within the active piezoelectric volume. This may, but need not facilitate suppression of spurious modes. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in a super high frequency (SHF) band. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in an extremely high frequency (EHF) band.

A resonator circuit device. The present invention provides for improved resonator shapes using egg-shaped, partial egg-shaped, and asymmetrical partial egg-shaped resonator structures. These resonator shapes are configured to give less spurious mode/noise below the resonant frequency (F.sub.s) than rectangular, circular, and elliptical resonator shapes. These improved resonator shapes also provide filter layout flexibility, which allows for more compact resonator devices compared to resonator devices using conventionally shaped resonators.

A resonator circuit device. This device can include a piezoelectric layer having a front-side electrode and a back-side electrode spatially configured on opposite sides of the piezoelectric layer. Each electrode has a connection region and a resonator region. Each electrode also includes a partial mass-loaded structure configured within a vicinity of its connection region. The front-side electrode and the back-side electrode are spatially configured in an anti-symmetrical manner with the resonator regions of both electrodes at least partially overlapping and the first and second connection regions on opposing sides. This configuration provides a symmetric acoustic impedance profile for improved Q factor and can reduce the issues of misalignment or unbalanced boundary conditions associated with conventional single mass-loaded perimeter configurations.

A bulk acoustic wave resonator device comprises a piezoelectric material layer, a first metal layer having a lower surface disposed on the upper surface of the piezoelectric material layer, a second metal layer having an upper surface disposed on the lower surface of the piezoelectric material layer, and an oxide raised frame disposed between the lower surface of the first metal layer and the upper surface of the second metal layer and surrounding a central active region of the bulk acoustic wave resonator device, the central active region having a first side and a second side, the oxide raised frame having a width on the first side of the central active region that is different from the width of the oxide raised frame on the second side of the central active region to improve an operating parameter of the bulk acoustic wave resonator.

The present disclosure provides a bulk acoustic wave resonance device, a bulk acoustic wave filter device and a radio frequency front end device. The bulk acoustic wave resonance device includes a first layer including a cavity disposed at a first side of the first layer; a first electrode layer disposed in the cavity; a second layer disposed at the first side and disposed on the first electrode layer, and the second layer is a flat layer and covers the first cavity; and a second electrode layer disposed at the first side and disposed on the second layer, and the first electrode layer includes at least two first electrode bars or the second electrode layer includes at least two second electrode bars. The present disclosure can increase the difference between acoustic impedance of a resonance region and a non-resonance region, thereby increasing Q value of the resonance device.

The invention provides a film bulk acoustic resonator including a layered structure composed of a top electrode, a piezoelectric layer and a bottom electrode, and a substrate; a reflective interface is arranged between the bottom electrode and the substrate; and by defining the shape of all or part of the layered structure, the purpose of suppressing the lateral mode can be achieved, and without adding new process, the manufacturing cost of the device can be controlled, and the benefit of product development can be maximized.

An acoustic wave filter device with two-stage acoustic wave filters is provided. Each of the two stages includes a respective acoustic wave filter element. A first acoustic wave filter element (100a) includes a first input electrode (150a), a first output electrode (174a), and a first counter electrode (120a). The first input electrode and the first output electrode are located on a top surface of piezoelectric layer (650), and the first counter electrode is located on a bottom surface of the piezoelectric layer. A second acoustic wave filter element (100b) includes a second input electrode (154b), a second output electrode (174b), and a second counter electrode (120b). The second input electrode and the second output electrode are located on the top surface of the piezoelectric layer, and the second counter electrode is located on a bottom surface of the piezoelectric layer. The two acoustic wave filter elements are connected in series through a common floating electrode (602).

Filter devices are disclosed. A filter device includes a piezoelectric plate comprising a supported portion, a first diaphragm, and a second diaphragm. The supported portion is attached to a substrate and the first and second diaphragms spans respective cavities in the substrate. A first interdigital transducer (IDT) has interleaved fingers on the first diaphragm. A second interdigital transducer (IDT) has interleaved fingers on the second diaphragm. A first dielectric layer is between the interleaved fingers of the first IDT, and a second dielectric layer is between the interleaved fingers of the second IDT. A thickness of the first dielectric layer is greater than a thickness of the second dielectric layer. The piezoelectric plate and the first and second IDTs are configured such that radio frequency signals applied to first and second IDTs excite primary shear acoustic modes in the respective diaphragms.

Piston mode Lamb wave resonators are disclosed. A piston mode Lamb wave resonator can include a piezoelectric layer, such as an aluminum nitride layer, and an interdigital transducer on the piezoelectric layer. The piston mode Lamb wave resonator has an active region and a border region, in which the border region has a velocity with a lower magnitude than a velocity of the active region. The border region can suppress a transverse mode.

A third through hole is formed in a crystal resonator plate of a crystal resonator to penetrate between a first main surface and a second main surface. A through electrode of the third through hole is conducted to a first excitation electrode. A seventh through hole is formed in a first sealing member of the crystal resonator to penetrate between a first main surface and a second main surface. The through electrode of the third through hole is conducted to the through electrode of the seventh through hole. The third through hole is not superimposed to the seventh through hole in plan view.