A method of fabricating an RF filter comprising an array of resonators, the method comprising the steps of: (a) Obtaining a removable carrier with release layer; (b) Growing a piezoelectric film on a removable carrier; (c) Applying a first electrode to the piezoelectric film; (d) Obtaining a backing membrane on a cover, with or without prefabricated cavities between the backing film and cover; (e) Attaching the backing membrane to the first electrode; (f) Detaching the removable carrier; (g) Measuring and trimming the piezoelectric film as necessary; (h) Selectively etching away the piezoelectric layer to fabricate discrete resonator islands; (i) Etching down through coatings backing membrane, silicon dioxide and into silicon handle to form trenches; (j) Applying passivation layer into the trenches and around the piezoelectric islands; (k) Depositing a second electrode layer over the dielectric and piezoelectric film islands; (l) Applying connections for subsequent electrical coupling to an interposer; (m) Selectively remove second electrode material leaving coupled resonator arrays; (n) Create gasket around perimeter of the resonator array; (o) Thinning down cover of handle to desired thickness; (p) Optionally fabricating cavities between the silicon membrane and handle; (q) Dicing the wafer into flip chip single unit filter arrays; (r) Obtaining an interposer; (s) Optionally applying a dam to the interposer surface to halt overfill flow; (t) Coupling the flip chip single unit filter array to pads of the interposer by reflow of the solder cap; (u) Encapsulating with polymer overfill; and (v) Singulating into separate filter modules.

A method of fabricating an RF filter comprising an array of resonators comprising the steps of: Obtaining a removable carrier with release layer; Growing a piezoelectric film on a removable carrier; Applying a first electrode to the piezoelectric film; Obtaining a backing membrane on a cover, with or without prefabricated cavities between the backing film and cover; Attaching the backing membrane to the first electrode; Detaching the removable carrier; Measuring and trimming the piezoelectric film as necessary; Selectively etching away the piezoelectric layer to fabricate discrete resonator islands; Etching down through coatings and backing membrane to a silicon dioxide layer between the backing membrane and the cover to form trenches; Applying a passivation layer into the trenches and around the piezoelectric islands; Depositing a second electrode layer over the piezoelectric film islands and surrounding passivation layer; Applying connections for subsequent electrical coupling to an interposer; Selectively removing second electrode material leaving coupled resonator arrays; Creating a gasket around perimeter of the resonator array; Thinning down cover to desired thickness; Optionally fabricating upper cavities between the backing membrane and cover by drilling holes through the cover and then selectively etching away the silicon dioxide; Dicing the wafer into flip chip single unit filter arrays; Obtaining an interposer; Optionally applying a dam to the interposer surface to halt overfill flow; Coupling the flip chip single unit filter array to pads of the interposer by reflow of the solder cap; Encapsulating with polymer underfill/overfill; and Singulating into separate filter modules.

An acoustic wave device includes a first piezoelectric layer including a first main surface and a second main surface, a first support portion including a first support substrate that overlaps the first piezoelectric layer in a first direction, a first resonator provided on at least the first main surface of the first piezoelectric layer, a second piezoelectric layer including a third main surface and a fourth main surface, a second support portion including a second support substrate overlapping the second piezoelectric layer in the first direction, and a second resonator provided on at least the third main surface of the second piezoelectric layer. The first resonator and the second resonator each include a functional electrode. The support portion includes a space portion that overlaps at least a portion of the functional electrode of the resonator in a plan view in the first direction.

A surface acoustic wave device is disclosed. The surface acoustic wave device can include a ceramic substrate, a piezoelectric layer over the ceramic substrate, and an interdigital transducer electrode over the piezoelectric layer. The ceramic substrate can be a polycrystalline spinel substrate. The surface acoustic wave device can also include a temperature compensating layer over the interdigital transducer electrode.

An elliptic combiner circuit filters a first and second signal in a first and second frequency band. A first resonator is coupled to a first input via a first capacitor and a second input via a second capacitor. A second resonator is coupled to a first and second signal path, coupled to the first and second input, via a third and a fourth capacitor. A first inductor is coupled between the first and third capacitors, and between the second and fourth capacitors. A third resonator is coupled to the first and second signal paths via a fifth, sixth, and seventh capacitors. A fourth resonator is coupled to the first signal path and a terminated port via an eighth, ninth and tenth capacitors. A second inductor is coupled between the fifth and eighth capacitors, and between the seventh and tenth capacitors. An output outputs the first and second signals.

An acoustic wave device includes first and second acoustic wave resonators, each including a piezoelectric layer and a functional electrode, and an acoustic coupling layer laminated between the piezoelectric layer of each of the first and second acoustic wave resonators. Each of the functional electrodes of the first and second acoustic wave resonators includes at least one pair of electrode fingers. In each of the first and second acoustic wave resonators, when a thickness of the piezoelectric layer is defined as d and a center-to-center distance of the electrode fingers adjacent to each other is defined as p, d/p is about 0.5 or smaller. The first and second acoustic wave resonators face each other across the acoustic coupling layer.

Provided are a band-pass filter circuit and a multiplexer. The band-pass filter circuit includes an electromagnetic LC filter circuit and acoustic resonance units. At least one of the acoustic resonance units each includes at least one first acoustic resonator and at least one second acoustic resonator. The first acoustic resonator is connected in series between the band-pass filter circuit and the electromagnetic LC filter circuit. Each of the at least one second acoustic resonator is connected to a terminal of the at least one first acoustic resonator, where the first terminal of the band-pass filter circuit serves as an input terminal or output terminal of the band-pass filter circuit. One or more of the acoustic resonance units are connected on an input side of the electromagnetic LC filter circuit; and the remaining of the acoustic resonance units are connected on an output side of the electromagnetic LC filter circuit.

A surface acoustic wave device is disclosed. The surface acoustic wave device can include a ceramic substrate, a piezoelectric layer over the ceramic substrate, and an interdigital transducer electrode over the piezoelectric layer. The ceramic substrate can be a polycrystalline spinel substrate. The surface acoustic wave device can also include a temperature compensating layer over the interdigital transducer electrode.

The present disclosure relates to an acoustic wave device for asymmetric frequency bands and a manufacturing process for making the same. The disclosed acoustic wave device includes at least one first electrode (102:152), at least one second electrode (104:152), a first piezoelectric layer (114) with a recess (116), and a second piezoelectric layer (118) fully covering the recess. Herein, the at least one first electrode is formed over the first piezoelectric layer, and the at least one second electrode is formed over the second piezoelectric layer and confined within the recess. The second piezoelectric layer does not cover a portion of the first piezoelectric layer, which is vertically underneath the at least one first electrode. The first piezoelectric layer and the second piezoelectric layer are formed of different piezoelectric materials.

A filter (100) includes a piezoelectric layer (105); a first electrode (108), disposed at a first vertical face of the piezoelectric layer (105) and configured to receive an electric signal; and a second electrode (109), disposed at a second vertical face of the piezoelectric layer (105) and configured to output an electric signal, where the first vertical face and the second vertical face are two opposite sides of the piezoelectric layer (105).