A bulk acoustic resonator architecture is fabricated by epitaxially forming a piezoelectric film on a top surface of post formed from an underlying substrate. In some cases, the acoustic resonator is fabricated to filter multiple frequencies. In some such cases, the resonator device includes two different resonator structures on a single substrate, each resonator structure configured to filter a desired frequency. Including two different acoustic resonators in a single RF acoustic resonator device enables that single device to filter two different frequencies in a relatively small footprint.

A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a first solid acoustic mirror, a second solid acoustic mirror, a piezoelectric layer that is positioned between the first solid acoustic mirror and the second solid acoustic mirror, an interdigital transducer electrode on the piezoelectric layer, and a support substrate arranged to dissipate heat associated with the bulk acoustic wave. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave. The first solid acoustic mirror and the second solid acoustic mirror are arranged to confine acoustic energy of the bulk acoustic wave. The first solid acoustic mirror is positioned on the support substrate.

A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a first solid acoustic mirror, a second solid acoustic mirror, a piezoelectric layer that is positioned between the first solid acoustic mirror and the second solid acoustic mirror, an interdigital transducer electrode on the piezoelectric layer, and a support substrate arranged to dissipate heat associated with the bulk acoustic wave. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave. The first solid acoustic mirror and the second solid acoustic mirror are arranged to confine acoustic energy of the bulk acoustic wave. The first solid acoustic mirror is positioned on the support substrate.

A bulk acoustic wave resonator comprises a piezoelectric material layer, a first metal layer disposed on the upper surface of the piezoelectric material layer, a second metal layer disposed on the lower surface of the piezoelectric material layer, and a laterally distributed raised frame including a first raised frame disposed on the upper surface of the first metal layer and having an inner raised frame section with a tapered portion and a non-tapered portion and an outer raised frame section, and a second raised frame disposed beneath the first metal layer and the outer raised frame section, but not beneath the inner raised frame section, the inner raised frame section being laterally disposed from a central active region of the bulk acoustic wave resonator by a first distance, the outer raised frame section being laterally disposed from the central active region by a second distance greater than the first distance.

A transmit filter circuit includes an input terminal, an output terminal, plural series arm resonators, and a parallel arm resonator. The input terminal receives a transmit signal. The output terminal is electrically connected to an antenna. The plural series arm resonators are electrically connected in series with each other on a line between the input and output terminals. The plural series arm resonators include first and second series arm resonators. The first series arm resonator is closest to the output terminal. The second series arm resonator is second closest to the output terminal. A first end of the parallel arm resonator is electrically connected to a node between the first and second series arm resonators. A reference potential is provided to a second end of the parallel arm resonator. The resonant frequency of the first series arm resonator is higher than that of the second series arm resonator.

A method of manufacturing a bulk acoustic wave filter is provided, including: forming an acoustic reflection air cavity, a sacrificial layer, a seed layer, a lower electrode layer and a piezoelectric layer of n resonators on a substrate in sequence, wherein n is greater than or equal to 2; taking N from 1 to n for respectively repeating following steps: forming an N-th metal hard mask layer, defining an effective area of a first resonator to an N-th resonator by using a photolithography process, removing the N-th metal hard mask layer outside the effective area of the first resonator to the N-th resonator, oxidizing the piezoelectric layer outside the effective area of the first resonator to the N-th resonator to form an N-th oxidized part of the piezoelectric layer, and etching the N-th oxidized part of the piezoelectric layer; removing the metal hard mask layer of the effective area of the first resonator to the N-th resonator, so as to form the piezoelectric layer having different thicknesses of the first resonator to the N-th resonator; and forming an upper electrode layer on the piezoelectric layer having different thicknesses of the first resonator to the N-th resonator.

A method for fabricating bulk acoustic wave resonator with mass adjustment structure, comprising following steps of: forming a sacrificial structure mesa on a substrate; etching the sacrificial structure mesa such that any two adjacent parts have different heights, a top surface of a highest part of the sacrificial structure mesa is coincident with a mesa top extending plane; forming an insulating layer on the sacrificial structure mesa and the substrate; polishing the insulating layer to form a polished surface; forming a bulk acoustic wave resonance structure including a top electrode, a piezoelectric layer and a bottom electrode on the polished surface; etching the sacrificial structure mesa to form a cavity; the insulating layer between the polished surface and the mesa top extending plane forms a frequency tuning structure, the insulating layer between the mesa top extending plane and the cavity forms a mass adjustment structure.

An apparatus is disclosed for harmonic reduction with filtering. In example aspects, the apparatus includes a filter circuit with first and second filter ports, first and second lattice filters, and first and second signal manipulator circuits. The first signal manipulator circuit includes a first port, a second port, and a third port coupled to the first filter port. The first signal manipulator circuit splits an input signal into multiple split signals, shifts a phase thereof to produce at least one phase-shifted split signal, and provides the phase-shifted split signal to the first and second ports. The first lattice filter is coupled to the first port, and the second lattice filter is coupled to the second port. The second signal manipulator circuit includes a first port coupled to the first lattice filter, a second port coupled to the second lattice filter, and a third port coupled to the second filter port.

An integrated circuit film bulk acoustic resonator (FBAR) device having multiple resonator thicknesses is formed on a common substrate in a stacked configuration. In an embodiment, a seed layer is deposited on a substrate, and one or more multi-layer stacks are deposited on the seed layer, each multi-layer stack having a first metal layer deposited on a first sacrificial layer, and a second metal layer deposited on a second sacrificial layer. The second sacrificial layer can be removed and the resulting space is filled in with a piezoelectric material, and the first sacrificial layer can be removed to release the piezoelectric material from the substrate and suspend the piezoelectric material above the substrate. More than one multi-layer stack can be added, each having a unique resonant frequency. Thus, multiple resonator thicknesses can be achieved on a common substrate, and hence, multiple resonant frequencies on that same substrate.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.