An elastic wave device includes a piezoelectric substrate and an interdigital transducer (IDT) electrode. The IDT electrode is disposed on the piezoelectric substrate and includes an electrode layer including molybdenum as a main component. The duty ratio of the IDT electrode is about 0.3 to about 0.48.

A method and a band reject filter (BRF) using as acoustic resonators at least one of bulk acoustic wave (BAW) resonators and film bulk acoustic resonators (FBAR) are provided. The BRF includes at least one substrate having at least one of a plurality of capacitors formed thereon, the plurality of capacitors having capacitances selected to achieve a particular band reject response. The BRF also includes at least one die. At least one of a plurality of acoustic wave resonators are formed thereon. The plurality of acoustic wave resonators are one of BAW resonators and FBARs and are designed to have the same resonant frequency. A plurality of conductors between the substrate and the die are positioned to electrically connect the acoustic wave resonators and the capacitors.

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.

There is disclosed acoustic resonators and filter devices. An acoustic resonator includes a single-crystal piezoelectric plate having front and back surfaces, a portion of the piezoelectric plate forming a diaphragm. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. The piezoelectric plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm.

A high frequency circuit includes a first demultiplexing circuit including a first high pass filter and a low pass filter and a second demultiplexing circuit including a band elimination filter and a band pass filter, the second demultiplexing circuit being connected in series with the first demultiplexing circuit. At least one of the band elimination filter and the band pass filter includes an elastic wave resonator. An attenuation band of the band elimination filter and a pass band of the band pass filter is located between a pass band of the first high pass filter and a pass band of the low pass filter.

In some embodiments, a radio-frequency circuit or device can include a filter circuit having an input node and an output node. The filter circuit can further include a first assembly having one or more bulk acoustic wave resonators implemented electrically between the input node and the output node, and configured to filter a signal. The filter circuit can further include a second assembly having one or more surface acoustic wave resonators implemented electrically relative to the first assembly, and configured to suppress one or more harmonics resulting from the filtering of the signal by the first assembly.

An acoustic resonator includes: a central portion; an extension portion extended outwardly of the central portion; a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on a substrate, in the central portion; and an insertion layer disposed below the piezoelectric layer in the extension portion, wherein the piezoelectric layer includes a piezoelectric portion disposed in the central portion, and a bent portion disposed in the extension portion and extended from the piezoelectric portion at an incline depending on a shape of the insertion layer.

A bulk-acoustic wave filter device includes: a lower electrode layer disposed on the substrate; a bonding part disposed on the lower electrode layer, at an edge of the substrate; a ground part spaced apart from the bonding part; and a flow suppressing part disposed between the bonding part and the ground part, and offset with respect to the bonding part and the ground part.

A filter may include one or more series unit, and a shunt unit disposed between the one or more series unit and ground. The one or more series unit includes a plurality of series resonators which are selectively operated, and each of the plurality of series resonators includes a film bulk acoustic resonator.

A filter comprises a series unit, and a shunt unit disposed between the series unit and a ground. The shunt unit includes resonators that are selectively operated, and each of the shunt resonators includes a film bulk acoustic resonator.