Abstract: A carrier aggregation circuit can include a mid-band path having a filter assembly and a phase shifting circuit, to support one or more frequency bands. The circuit can further include first and second high-band paths each being configured to support a frequency band and having a filter and a phase shifting circuit. Selected high-band filter and the mid-band filter assembly can be configured to provide impedances having the same sign for imaginary parts, and the phase shifting circuit of the mid-band path can be configured to provide a desired reflection coefficient phase at one of the first and second high-band frequency bands. The circuit can further include a common node coupled to outputs of the mid-band, first high-band and second high-band paths, and a tuning circuit implemented to remove the imaginary part of the impedance of the mid-band filter assembly at the frequency band of the selected high-band filter.

Abstract: Fuse programming circuits, devices and methods. In some embodiments, a fuse circuit can include a fuse pad configured to receive a voltage, a fuse having a first end coupled to the fuse pad and a second end coupled to a switching element configured to enable a current to pass from the fuse pad to a ground potential.

Abstract: An electronic device comprises a first surface acoustic wave (SAW) resonator and a second SAW resonator, each including interleaved interdigital transducer (IDT) electrodes, the first and second SAW resonators being formed on a same piezoelectric substrate, the first SAW resonator having IDT electrodes with a different finger pitch than the IDT electrodes of the second SAW resonator; a dielectric material layer disposed on the IDT electrodes of the first and second SAW resonators; and a high velocity layer disposed within the dielectric material layer disposed on the IDT electrodes of the first SAW resonator, the second SAW resonator lacking a high velocity layer disposed within the dielectric material layer disposed on the IDT electrodes.

Abstract: A surface acoustic wave device is disclosed. The surface acoustic wave device can include a single crystal support layer, an intermediate single crystal layer positioned over the single crystal support layer, a lithium based piezoelectric layer positioned over the intermediate single crystal layer, and an interdigital transducer electrode positioned over the lithium based piezoelectric layer, the surface acoustic wave device configured to generate a surface acoustic wave. The single crystal layer can be a quartz layer, such as a z-propagation quartz layer. A thermal conductivity of the single crystal support layer is greater than a thermal conductivity of the intermediate single crystal layer, and the thermal conductivity of the single crystal support layer is greater than a thermal conductivity of the lithium based piezoelectric layer.

Abstract: A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a support substrate, a solid acoustic mirror on the support substrate, a piezoelectric layer on the solid acoustic mirror, and an interdigital transducer electrode on the piezoelectric layer. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave.

Abstract: Apparatus and methods for power amplifier signal limiting are disclosed. In certain embodiments, a power amplifier system includes a power amplifier that amplifies a radio frequency input signal, and a signal limiter operable to limit a signal power of the power amplifier when the radio frequency input signal exceeds a threshold. The signal limiter includes a radio frequency detector configured to generate a detection signal based on detecting a power level of the radio frequency input signal, and a latch configured to lock the signal limiter into an attenuating mode in response to the detection signal indicating that the threshold is exceeded.

Abstract: Aspects of this disclosure relate to methods of selectively shielded radio frequency modules. A radio frequency module can be provided with a radio frequency component and an antenna. A shielding layer can be formed over a portion of the radio frequency module such that the radio frequency component is shielded by the shielding layer and the antenna is unshielded by the shielding layer.

Abstract: Aspects of this disclosure relate to a radio frequency system with tunable notch filtering. The radio frequency system includes a first tunable filter and a second tunable filter. The first tunable filter is coupled between an output of a power amplifier and a radio frequency switch. The second tunable filter is coupled between an antenna switch and an antenna node. The second tunable filter has a notch at a lower frequency than a notch of the first tunable filter. Related methods and wireless communication devices are also disclosed.

Abstract: In order to reduce errors in the transfer of time from one clock domain to another clock domain, a first free running counter is incremented using a first clock signal. A free running second counter is incremented using a second clock signal, the second clock signal being asynchronous to the first clock signal. The first counter is sampled at a selected time based on a predetermined phase relationship between the first clock signal and the second clock signal to generate a sampled first counter value. The second counter is corrected based on the sampled first counter value.

Abstract: Multi-level envelope tracking systems with separate DC and AC paths are provided. In certain embodiments, an envelope tracking system for generating a power amplifier supply voltage for a power amplifier is provided. The envelope tracking system includes a multi-level supply (MLS) DC-to-DC converter that outputs multiple regulated voltages, an MLS modulator that controls selection of the regulated voltages over time based on an envelope signal corresponding to an envelope of a radio frequency (RF) signal amplified by the power amplifier, an AC path filter coupled between an output of the MLS modulator and the power amplifier supply voltage, and a DC path filter coupled between a DC voltage and the power amplifier supply voltage.

Abstract: Aspects of this disclosure relate to an elastic wave device. The elastic wave device includes a sub-wavelength thick piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, and a high velocity layer configured to inhibit an elastic wave from leaking from the piezoelectric layer at anti-resonance.

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: Disclosed are embodiments of synthetic garnet materials for use in radiofrequency applications. In some embodiments, increased amounts of bismuth can be added into specific sites in the crystal structure of the synthetic garnet in order to boost certain properties, such as the dielectric constant and magnetization. Accordingly, embodiments of the disclosed materials can be used in high frequency applications, such as in base station antennas.

Abstract: Apparatus and methods for power amplifier output matching is disclosed. In one aspect, there is provided an output matching circuit including an input configured to receive an amplified radio frequency signal from a power amplifier, a first output, and a second output. The output matching circuit further includes a first matching circuit electrically connected between the input of the output matching circuit and the first output, the first matching circuit configured to suppress harmonics of a fundamental frequency of the amplified radio frequency signal when the amplified radio frequency signal is within a first band. The output matching circuit further includes a second matching circuit electrically connected between the input of the output matching circuit and the second output, the second matching circuit configured to suppress harmonics of the fundamental frequency of the amplified radio frequency signal when the amplified radio frequency signal is within a second band different from the first band.

Abstract: An acoustic wave device with a bent section is disclosed. The acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode on the piezoelectric layer. The bent section is arranged to create a curvature in a waveguide of the acoustic wave device to suppress a transverse spurious mode of the acoustic wave device.

Abstract: Apparatus and methods for oscillation suppression of cascode power amplifiers are provided herein. In certain implementations, a power amplifier system includes a cascode power amplifier including a plurality of transconductance devices that operate in combination with a plurality of cascode devices to amplify a radio frequency input signal. The power amplifier system further includes a bias circuit that biases the plurality of cascode devices with two or more bias voltages that are decoupled from one another at radio frequency to thereby inhibit the cascode power amplifier from oscillating.

Abstract: This disclosure relates to a transmission line for high performance radio frequency (RF) applications. One such transmission line can include a bonding layer configured to receive an RF signal, a barrier layer, a diffusion barrier layer, and a conductive layer proximate to the diffusion barrier layer. The diffusion barrier layer can have a thickness that allows a received RF signal to penetrate the diffusion barrier layer to the conductive layer. In certain implementations, the diffusion barrier layer can be nickel. In some of these implementations, the transmission line can include a gold bonding layer, a palladium barrier layer, and a nickel diffusion barrier layer.

Abstract: Aspects of this disclosure relate to an impedance transformation circuit for use in an amplifier, such as a low noise amplifier. The impedance transformation circuit includes a matching circuit including a first inductor. The impedance transformation circuit also includes a second inductor. The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier.

Abstract: A piezoelectric microelectromechanical system microphone comprises a frame, a film of piezoelectric material including slits defining a plurality of independently displaceable piezoelectric elements within an area defined by a perimeter of the frame, bases of the plurality of piezoelectric elements mechanically secured to the frame, tips of the plurality of piezoelectric elements being free to be displaced in a direction perpendicular to a plane defined by the frame responsive to impingement of sound waves on the plurality of piezoelectric elements, and edge extensions extending from edges of the plurality of piezoelectric elements in the direction perpendicular to the plane defined by the frame to reduce a 3 dB roll-off frequency of the piezoelectric microelectromechanical system microphone.

Abstract: A fuse circuit that permits a fuse to be selected and programmed using a single fuse pad. The fuse circuit includes a fuse pad to receive a first voltage, a fuse coupled in series with a voltage controlled switch between the fuse pad and a reference node, and a switch control circuit coupled in series between the fuse pad and the reference node and in parallel with the fuse and the voltage controlled switch, the switch control circuit being configured to select and program the fuse responsive to the first voltage received at the fuse pad. The fuse pad may subsequently be grounded and a sense circuit may be coupled to the fuse to measure a voltage dropped across the fuse to determine whether the fuse has been programmed.