Abstract: Aspects of this disclosure relate to an acoustic wave resonator having at least two resonant frequencies. An acoustic wave filter can include series acoustic wave resonators and shunt acoustic wave resonators together arranged to filter a radio frequency signal. A first shunt resonator of the shunt acoustic wave resonators can include an interdigital transducer electrode and have at least a first resonant frequency and a second resonant frequency. Related acoustic wave resonators, multiplexers, wireless devices, and methods are disclosed.

Abstract: A surface acoustic wave resonator comprises interdigital transducer (IDT) electrodes disposed on an upper surface of a piezoelectric substrate between first and second reflector gratings each including reflector electrodes. The IDT electrodes include a central region having a first width in a direction perpendicular to an extension direction of the IDT electrodes and edge regions each having a second width on opposite sides of the central region. The IDT electrodes have a lesser average pitch in the central region than an average pitch of the IDT electrodes in each of the edge regions. The reflector electrodes have a lesser average pitch than the average pitch of the IDT electrodes in the central region.

Abstract: Disclosed herein are silicon-on-insulator (SOI) switches and associated control circuits having level shifters configured to provide increased voltages (positive and/or negative) to the switches. The disclosed level shifters can be configured to provide increased voltages and can be used with high-linearity switches and/or can improve the linearity of switches. The improved switch performance can improve front end module performance for applications such as carrier aggregation (CA) and multiple input multiple output (MIMO) as well as with protocols such as Long-Term Evolution Advanced (or LTE-A).

Abstract: A film bulk acoustic wave resonator (FBAR) includes a piezoelectric film disposed in a central region defining a main active domain in which a main acoustic wave is generated during operation and in recessed frame regions disposed laterally on opposite sides of the central region, and an electrode disposed on an upper surface of the piezoelectric film, the electrode having a lesser thickness in the recessed frame regions than the thickness of the electrode in the central region to increase a quality factor of the FBAR.

Abstract: Apparatus and methods for envelope controlled radio frequency (RF) switches are provided. In certain embodiments, a power amplifier provides an RF signal to an antenna by way of an RF switch. Additionally, the envelope signal is used not only to control a power amplifier supply voltage of the power amplifier, but also to control a regulated voltage used to turn on the RF switch. For example, a level shifter can use a regulated voltage from charge pump circuitry to turn on the RF switch, and the envelope signal can be provided to the charge pump circuitry and used to control the voltage level of the regulated voltage over time.

Abstract: Apparatus and methods for reconfigurable antenna systems are provided herein. In certain configurations, an antenna system includes an antenna element, a tuning conductor adjacent to and spaced apart from the antenna element, and a switch electrically connected between the tuning conductor and a reference voltage, such as ground. The tuning conductor is operable to load the antenna element, and the switch selectively connects the tuning conductor to the reference voltage to provide tuning to the antenna element.

Abstract: A radio-frequency impedance tuner can include first and second nodes, a bypass path, first and second series capacitance paths, and an inductance path, with each path being implemented between the first and second nodes and including a switch configured to allow the path to couple or uncouple the first and second nodes. The tuner can further include first and second shunt paths, with each shunt path being implemented between the second node and ground and including a switch configured to allow the shunt path to couple or uncouple the second node and the ground. The tuner can further include a switchable grounding path implemented along the inductance path and configured to allow the inductance path to function as a series inductance path between the first and second nodes, or as a shunt inductance path between the ground and a node along the inductance path.

Abstract: A circuit comprises an amplifier network including a first amplifier and a second amplifier and a first transistor having a first base. The first transistor is thermally isolated from the second amplifier. The circuit further comprises a second transistor having a second base. The second transistor is thermally linked to the second amplifier. The circuit further comprises coupling circuitry configured to couple the first base to the second base.

Abstract: Disclosed herein are ceramic materials, such as bismuth substituted garnets, which can have high curie temperatures and high dielectric constants. In certain implementations, indium can be incorporated into the ceramic to improve certain properties and to avoid calcium compensation. The ceramic materials disclosed herein can be particular advantageous for below resonance applications.

Abstract: Circuits, systems, devices, and methods related to a switch with an integrated Schottky barrier contact are discussed herein. For example, a radio-frequency switch can include an input node, an output node, and a transistor connected between the input node and the output node. The transistor can be configured to control passage of a radio-frequency signal from the input node to the output node. The transistor can include a first Schottky diode integrated into a drain of the transistor and/or a second Schottky diode integrated into a source of the transistor. The first Schottky diode and/or the second Schottky diode can be configured to compensate a non-linearity effect of the radio-frequency switch.

Abstract: Disclosed herein are switching or other active FET configurations that implement a branch design with one or more interior FETs of a main path coupled in parallel with one or more auxiliary FETs of an auxiliary path. Such designs include a circuit assembly for performing a switching function that includes a branch with a plurality of auxiliary FETs coupled in series and a main FET coupled in parallel with an interior FET of the plurality of auxiliary FETs. The body nodes of the FETs can be interconnected and/or connected to a body bias network. The body nodes of the FETs can be connected to body bias networks to enable individual body bias voltages to be used for individual or groups of FETs.

Abstract: Aspects of this disclosure relate to a multiplexer that includes an acoustic wave filter including acoustic wave resonators on at least two die with a transmission line electrically connecting the acoustic wave resonators on the two die. The acoustic wave filter can include a plurality of acoustic wave resonators on a first die electrically connected to at least one acoustic wave resonator on a second die via the transmission line. The acoustic wave resonator on the second die can provide a relatively high impedance at a respective passband of one or more other filters of the multiplexer. This can reduce effects of the transmission line of the acoustic wave filter on a respective passband of one or more other filters of the multiplexer.

Abstract: A switching circuit comprises a first filter, a second filter and a plurality of switches. The first filter is configured to filter a first frequency band, a second frequency band that is adjacent to the first frequency band and a gap band between the first frequency band and the second frequency band. The second filter is configured to filter the second frequency band. The plurality of switches is configured to route signals from an antenna through one of the first filter and second filter.

Abstract: Doherty power amplifiers with coupled line combiners are provided herein. In certain embodiments, a power amplifier system includes a carrier amplifier having a carrier output that provides a first radio frequency signal, a peaking amplifier having a peaking output that provides a second radio frequency signal, and a coupled line combiner that combines the first radio frequency signal and the second radio frequency signal to generate a radio frequency output signal at an output terminal. The coupled line combiner includes a first conductor line connected between the peaking output and a reference voltage, a second conductor line electromagnetically coupled to the first conductor line, a third conductor line connected between the carrier output and the reference voltage, and a fourth conductor line electromagnetically coupled to the third conductor line and connected between the output terminal and the second conductor line.

Abstract: An acoustic wave device is disclosed. The acoustic wave device includes a piezoelectric layer, an interdigital transducer electrode positioned over the piezoelectric layer, and an anti-refection layer over a conductive layer of the interdigital transducer electrode. The conductive layer can include aluminum, for example. The anti-reflection layer can include silicon. The anti-reflection layer can be free from a material of the interdigital transducer electrode. The acoustic wave device can further include a temperature compensation layer positioned over the anti-reflection layer in certain embodiments.

Abstract: Examples of the disclosure include a controller having a mode of operation including one of an on mode and an off mode, the controller including a voltage rail node, a reference node, at least one powered component configured to generate a bandgap voltage signal based on a rail voltage at the voltage rail node, a switching device coupled in series between the reference node and the at least one powered component and configured to provide a conductive path through the at least one powered component from the voltage rail node to the reference node in response to the controller being in the on mode, and to interrupt the conductive path through the at least one powered component in response to the controller being in the off mode.

Abstract: Radio-frequency switches and related circuits are disclosed. In some embodiments, a switching device can include a series arm having transistors implemented in a stack configuration between first and second nodes. The switching device can further include a shunt arm having transistors implemented in a stack configuration between the first node and a ground node. The switching device can further include a bias architecture having a series arm bias circuit and a shunt arm bias circuit. The series arm bias circuit can be configured to bias the transistors of the series arm and include a gate-gate resistor that couples each pair of neighboring transistors. The shunt arm bias circuit can be configured to bias the transistors of the shunt arm and include a gate-gate resistor that couples each pair of neighboring transistors.

Abstract: A capless impedance tuner can include first node and second nodes, a first series path, a second series path, and an inductance path, each between the first node and the second node and including a switch to allow the path to couple or uncouple the first and second nodes. Each series path can be configured to allow a substantially continuous flow of a direct current between the first node and the second node when coupled. The tuner can further include a shunt path with a switch to allow coupling or uncoupling of the second node and ground. The tuner can further include a switchable grounding path implemented along the inductance path and configured to allow the inductance path to function as a series inductance path between the first and second nodes, or as a shunt inductance path between the ground and a node along the inductance path.

Abstract: Apparatus and methods for bias switching of power amplifiers are provided herein. In certain configurations, a power amplifier system includes a power amplifier that provides amplification to a radio frequency (RF) signal, a power management circuit that controls a voltage level of a supply voltage of the power amplifier, and a bias control circuit that biases the power amplifier. The power management circuit is operable in multiple supply control modes, such as an average power tracking (APT) mode and an envelope tracking (ET) mode. The bias control circuit is configured to switch a bias of the power amplifier based on the supply control mode of the power management circuit.

Abstract: A power amplifier including a cascode output stage, a bias circuit, and a temperature compensation and bias boost circuit. The cascode output stage has an input and an output and includes first and second transistors connected in series. A base of the first transistor is coupled to the input, an emitter of the first transistor is coupled to a reference potential, a collector of the first transistor is coupled to an emitter of the second transistor, and a collector of the second transistor is coupled to a supply voltage and the output. The bias circuit is coupled to the base of the second transistor. The bias boost circuit is coupled to the base of the first transistor, compensates for changes in temperature of the cascode output stage, and increases a bias current provided to the first transistor responsive to an increase in the temperature of the cascode output stage.