Abstract: A switching circuit comprises a first series switch coupled to a first output port, the first series switch including a first field-effect transistor (FET), a second FET, a third FET, a fourth FET, a fifth FET, and a sixth FET, a second series switch coupled to a second output port, and coupling circuitry configured to couple a gate of the fifth FET and a gate of the sixth FET to a first node, a source of the fifth FET and a drain of the sixth FET to a second node, a source of the first FET and a drain of the second FET to a third node, a gate of the first FET and a drain of the fifth FET to a fourth node, a gate of the second FET and a source of the sixth FET to a fifth node, the fourth node and the fifth node to a first gate voltage, and the first node to a second gate voltage that is different than the first gate voltage.

Abstract: A front-end module of a wireless device can replace a passive duplexer with an active duplexer that uses metamaterial matching circuits. The active duplexer can be formed from a power amplifier circuit and a low noise amplifier circuit that each include a metamaterial matching circuit. The combination of a power amplifier circuit and a low noise amplifier circuit that each utilize metamaterials to form the associated matching circuit can provide the functionality of a duplexer without including the additional circuitry of a stand-alone or passive duplexer. Thus, in certain cases, the front-end module can provide duplexer functionality without including a separate duplexer. Advantageously, in certain cases, the size of the front-end module can be reduced by eliminating the passive duplexer. Further, the loss introduced into the signal path by the passive duplexer is eliminated improving the performance of the communication system that includes the active duplexer.

Abstract: Packaged surface acoustic wave devices are provided. The packaged surface acoustic wave devices are relatively thin and can have a height of less than 220 micrometers. The packaged surface acoustic wave device includes a photosensitive resin over a conductive structure which may be formed by a plating process. The conductive structure may overlie a cavity-defining structure encapsulating a surface acoustic wave device, the cavity-defining structure including walls and a roof. The photosensitive resin can include a phenol resin. The photosensitive resin can be relatively thin. Edge portions of a piezoelectric substrate can be free from the photosensitive resin.

Abstract: Disclosed herein are embodiments of an enhanced resonant frequency hexagonal ferrite material and methods of manufacturing. The hexagonal ferrite material can be Y-phase strontium hexagonal ferrite material. In some embodiments, strontium can be substituted out for a trivalent or tetravalent ion composition including potassium, thereby providing for advantageous properties.

Abstract: A line card in a network box receives a SyncE clock signal and an input synchronization (SYNC) signal. A phase-lock loop (PLL) in the line card receives the SyncE clock signal as a reference clock signal and generates an output SyncE clock signal. The line card regenerates a SYSCLK signal using a digitally controlled oscillator that receives a timing signal from the SyncE PLL and receives a control signal from control logic on the line card. The frequency and phase information contained in the SYNC signal is utilized to control the DCO. The SYSCLK signal is divided to generate an output SYNC signal. The control logic uses the time difference between the input SYNC signal and a SYNC feedback signal to control the DCO to provide a zero delay SYNC output signal. The output SYNC signal and the SYSCLK signal control a time of day counter in the line card.

Abstract: A method for converting voltage is disclosed, including implementing a first DC-DC converter in a power management unit; implementing a second DC-DC converter in the power management unit; implementing a controller communicatively coupled to a first output line of the first DC-DC converter and communicatively coupled to a second output line of the second DC-DC converter; coupling the power management unit to a supply voltage; and providing one or more output voltages on the first output line and the second output line.

Abstract: An acoustic wave resonator comprises a piezoelectric material formed of aluminum nitride (AlN) doped with calcium (Ca) to enhance performance of the acoustic wave resonator.

Abstract: A wireless device comprising a first antenna and second antenna, a transceiver and a radio frequency front end system electrically coupled between the transceiver and the antennas. The RF front end system includes a first module operable to provide a high band transmit signal to the first antenna, receive a first high band receive signal and a first mid band receive signal from the first antenna. The first high band receive signal has a frequency range greater than that of the first mid band receive signal. The RF front end system further includes a second module operable to provide a mid band transmit signal to the second antenna, receive a second mid band receive signal and a second high band receive signal from the second antenna. The second high band receive signal has a frequency range greater than that of the second mid band receive signal.

Abstract: Apparatus and methods for retraining digital pre-distortion are disclosed. In certain embodiments, a mobile device includes a transmit chain and a front end system. The transmit chain generates a transmit signal and converts the transmit signal to a radio frequency input signal, and includes a digital pre-distortion circuit that provides digital pre-distortion to the transmit signal. The front end system includes a power amplifier that amplifies the radio frequency input signal to generate a radio frequency output signal, and a power detector that generates a detection signal based on detecting an output power of the power amplifier. The detection signal controls initiation of a retraining sequence of the digital pre-distortion circuit.

Abstract: Apparatus and methods for sounding reference signal (SRS) switching are provided. In certain embodiments, transmit path resources of user equipment (UE) are used to reduce or eliminate the impairment of SRS upon transport capacity. Furthermore, the transmit path resources can be used for other purposes, and thus SRS switching time can be reduced by re-using transmit path resources that may be included for other purposes. The teachings herein can be used to achieve SRS switching of 0 ?s, thereby eliminating the impact of switching timing constraints for SRS symbols on transport capacity.

Abstract: Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes a multi-level switching circuit having an output that provides an output current that changes in relation to an envelope signal indicating an envelope of the RF signal when the envelope tracker is operating in an envelope tracking mode. The multi-level switching circuit includes a multi-level supply (MLS) modulator that receives multiple regulated voltages of different voltage levels, and an MLS control circuit that controls the selection of the MLS modulator over time based on the envelope signal. When transitioning the MLS modulator from selection of one regulated voltage level to another regulated voltage level, the MLS control circuit provides a soft transition to gradually switch the regulated voltage levels.

Abstract: The disclosure relates to a signal combiner for a Doherty power amplifier architecture, the signal combiner including a termination circuit on an isolation port, the termination circuit being tuned to improve performance of the Doherty power amplifier. The architecture includes a carrier amplifier and a peaking amplifier. The peaking amplifier modulates the load seen by the carrier amplifier, allowing the carrier amplifier to remain in high-efficiency, saturated operation even at back-off. This load modulation can be achieved using impedance matching networks having an impedance matched to a specific frequency. The architectures include tuned or tailored signal combiners with termination circuits on isolation ports. The termination circuits are tuned or tailored for particular operating frequencies to enhance operation.

Abstract: Devices and methods related to nested filters. In some embodiments, a radio-frequency device can include a substrate, and first and second filter devices mounted on the substrate with respective support structures, such that at least a portion of the second filter device is positioned in a space defined by an underside of the first filter device and the support structures for the first filter device. Such a radio-frequency device can be, for example, a packaged module for use in an electronic device such as a wireless device.

Abstract: A method for estimating jitter of a clock-signal-under-test includes generating a phase-adjusted clock signal based on an input clock signal and a feedback clock signal using a frequency-divided clock signal. The method includes generating N digital time codes for each phase adjustment of P phase adjustments of the phase-adjusted clock signal using a reference clock signal. Each digital time code of the N digital time codes corresponds to a first edge of a clock signal based on the phase-adjusted clock signal. P is a first integer greater than zero and N is a second integer greater than zero. The method includes generating a jitter estimate using an estimated standard deviation of a distribution of edges of the clock signal based on the N digital time codes for each of the P phase adjustments.

Abstract: Multi-level envelope tracking systems with adjusted voltage steps 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, and a modulator output filter coupled between an output of the MLS modulator and the power amplifier supply voltage. The envelope tracking system further includes a switching point adaptation circuit configured to control the voltage level of the regulated voltages outputted by the MLS DC-to-DC converter based on a power level of the RF signal.

Abstract: Apparatus and methods for biasing power amplifiers are provided herein. In certain embodiments, a power amplifier includes a bipolar transistor having a base biased by a bias network having a reactance that controls an impedance at the transistor base to achieve substantially flat phase response over large dynamic power levels. For example, the bias network can have a frequency response, such as a high-pass or band-pass response, that reduces the impact of power level on phase distortion (AM/PM).

Abstract: An integrated circuit has an isolation capacitor structure that reduces the risk of breakdown from high electric fields at the edge of the top metal plate of the capacitor. The capacitor structure includes a bottom metal plate above a substrate. A first dielectric layer of a first dielectric material is formed between the bottom metal plate and the top metal plate. The capacitor structure also includes a thin narrow ring formed of a second dielectric material located under a portion of the top metal plate. The second dielectric material has a higher dielectric constant than the first dielectric material. The thin narrow ring follows the shape of the edge of the top metal plate with a portion of the ring underneath the top metal plate and a portion outside the edge of the top metal plate to thereby be located at a place of the maximum electric field.

Abstract: A method for calibrating a receiver of an isolator product includes adjusting a peaking frequency of a receiver signal path of a first integrated circuit die of the isolator product and a gain of the receiver signal path based on a predetermined peaking frequency, a predetermined gain, a first level of a diagnostic signal during a first interval, and a second level of the diagnostic signal during a second interval. The first interval and the second interval are non-overlapping intervals. The method may include receiving a calibration signal on a differential pair of nodes of the receiver signal path of the first integrated circuit die. The method may include generating a diagnostic signal corresponding to an average amplitude of a received version of the calibration signal.

Abstract: A surface acoustic wave (SAW) resonator comprises a plurality of interdigital transducer electrodes disposed on a multilayer piezoelectric substrate (MPS) including a layer of piezoelectric material having a lower surface bonded to an upper surface of a layer of a second material different from the piezoelectric material that improves the temperature stability and reliability of the SAW resonator, and a layer of dielectric material disposed on an upper surface of the interdigital transducer electrodes and MPS.

Abstract: Multiplexers are disclosed. A multiplexer can include a first filter and a second filter that are coupled to a common node. The second filter can include a first type of acoustic wave resonators (e.g., bulk acoustic wave resonators) and a series acoustic wave resonator of a second type (e.g., a surface acoustic wave resonator) that is coupled between the acoustic wave resonators of the first type and the common node. The first filter can provide a single-ended radio frequency signal. In certain embodiments, the first filter can be a receive filter and the second filter can be a transmit filter.