A filter includes a signal path connecting an input terminal and an output terminal one or more series arm circuits on the signal path, and one or more parallel arm circuits connected to one or more nodes disposed on the signal path and a ground electrode. The one or more series arm circuits define any of a section between nodes adjacent to each other, a section between a node closest to the input terminal and the input terminal, and a section between a node closest to the output terminal and the output terminal. Among the one or more series arm circuits and the one or more parallel arm circuits, one circuit does not include any acoustic wave resonator, and another circuit includes an acoustic wave resonator.

A micro-acoustic RF filter comprises first and second ports (101, 102). First and a second signal paths (120, 110) are coupled between the first and second ports and include a corresponding resonator (111, 121). The resonator of at least one of the signal paths is a micro-acoustic resonator. One of the signal paths includes also a phase shifter (232) serially connected with the resonator (111). The micro-acoustic RF filter achieves a broad passband determined by the resonance frequencies of the micro-acoustic resonators. The filter allows flexible adaption of the passband and stopband performance.

A bulk acoustic resonator filter includes: a series bulk acoustic resonator electrically connected, in series, between first and second ports through which a radio frequency (RF) signal passes; a second shunt bulk acoustic resonator, electrically shunt connected between the series bulk acoustic resonator and a ground and having a resonance frequency lower than that of the series bulk acoustic resonator; and a first shunt bulk acoustic resonator electrically connected to the second shunt bulk acoustic resonator in series and having a resonance frequency higher than that of the second shunt bulk acoustic resonator. One or both of the series bulk acoustic resonator and the first shunt bulk acoustic resonator includes a first electrode disposed above a substrate; a piezoelectric layer disposed on the first electrode; a second electrode disposed on the piezoelectric layer; and a trench formed in an upper surface or above the second electrode and recessed downwardly.

A method and apparatus for modifying or controlling a resonator connected to a signal loop having an input, an output, and a closed loop frequency response. The signal loop has a primary resonator having a primary frequency response. There is at least one adjustable resonator having an adjustable frequency and a secondary Q-factor. An adjustable scaling block applies a gain factor. A controller is connected to the at least one adjustable resonator and the adjustable scaling block. The controller has instructions to adjust the closed loop frequency response toward a desired closed loop frequency response by controlling the adjustable frequency of the at least one adjustable resonator and the gain factor of the adjustable scaling block.

An acoustic wave filter includes at least three segmented resonator devices connected in series to one another and aligned in a direction that crosses an acoustic wave propagation direction and each including an InterDigital Transducer (IDT) electrode, and centers of respective IDT electrodes of an adjacent pair of the at least three segmented resonator devices in the acoustic wave propagation direction are not aligned when seen from a direction orthogonal to the acoustic wave propagation direction.

A device includes a piezoelectric layer on a substrate and including a portion included in an acoustic resonator, a first conductive layer on the piezoelectric layer and including a first electrode of the acoustic resonator on a first side of resonator portion of the piezoelectric layer, and a second conductive layer on the piezoelectric layer and including a second electrode of the acoustic resonator on a second side of the resonator portion of the piezoelectric layer. An insulating layer is disposed on the second conductive layer and an interconnection metal layer is electrically connected to the second conductive layer or the first conductive layer and has a portion extending onto the insulating layer and overlapping a portion of the second conductive layer to provide a capacitor electrode of a capacitor coupled to the first electrode and/or the second electrode.

A wireless communication device includes a first transceiver operable according to a first radio technology and a second transceiver operable according to a second radio technology and operable concurrently with the first transceiver. The wireless communication device further includes an antenna configured to transmit radio transmissions of the second transceiver, and a filter circuit coupling the second transceiver with the antenna. The filter circuit includes a first frequency path and a second frequency path in parallel. The first frequency path passes a first set of frequencies of the radio transmissions and the second frequency path passes a second set of frequencies of the radio transmissions. One of the first frequency path or the second frequency path is configured to filter the radio transmissions of the second transceiver to remove signals corresponding to the one or more operating frequencies of the first transceiver from the radio transmissions of the second transceiver.

A filter device includes a first filter including a first input terminal, a first output terminal, a first series arm including first series arm resonators, and first parallel arms connected to the first series arm and each including a first parallel arm resonator, the first filter having a pass band in a predetermined frequency band, a second filter including a second input terminal, a second output terminal, a second series arm including second series arm resonators, and second parallel arms connected to the second series arm and each including a second parallel arm resonator, the second filter having a pass band in the predetermined frequency band, a substrate including the first and second filters, and an inductor connected between a ground terminal and a parallel arm resonator included in at least one parallel arm of the first and second parallel arms.

A BAW resonator (BAWR) with improved power durability and improved heat resistance is provided. The resonator comprises a layer stack with a piezoelectric material (PM) between a bottom electrode (ELI) and a top electrode (EL2) and a shunt path parallel (PCPP) to the layer stack provided to enable an RF signal to bypass the layer stack, e.g. to ground (GND). The shunt path (PCPP) has a temperature dependent conductance with a negative temperature coefficient, NTC, of resistance. When the temperature of the device rises due to high power operation, currents that would otherwise permanently damage the device are shunted to ground or another dedicated terminal by the temperature dependent shunt path. Upon cooling down normal operation is resumed.

A communications module includes a module substrate composed of a plurality of insulating layers, a plurality of wiring layers, and a plurality of wiring vias; and a filter module disposed on the module substrate. At least one of the wiring layers overlaps the filter module in a thickness direction of the module substrate and is connected to a ground potential to function as a ground layer, and an entirety of at least one of the wiring layers and at least one of the wiring vias disposed in a first region in the thickness direction of the module substrate between the filter module and the ground layer are electrically connected to the filter module.