Aspects of the disclosure relate to a radio frequency phase shifter. An example includes an amplification stage to produce an amplified voltage, the amplification stage having a first amplifier with a first input coupled to a first output of a hybrid coupler and a second amplifier with a complementary second input coupled to a complementary second output of the hybrid coupler. A vector modulation stage coupled to the amplification stage receives the amplified voltage and produces a modulated vector, the vector modulation stage has an in-phase section and a quadrature section to control the phase of the modulated vector in response to a phase control signal. A varactor coupled across the first input and the second input of the amplification stage adjusts the capacitance between the first input and the second input in response to a capacitance control signal.

This application provides a wireless charger and a control method. The wireless charger includes a class-E power amplifier and a tunable impedance circuit that is connected to an output end of the class-E power amplifier. The class-E power amplifier includes a switching transistor and a tunable capacitance circuit that is parallelly connected to the switching transistor. The wireless charger further includes a control unit, configured to obtain a constraint condition of the class-E power amplifier; determine N1 target equivalent load impedances of the class-E power amplifier based on the constraint condition; and adjust a capacitance value of the tunable capacitance circuit in the class-E power amplifier, and adjust an impedance value of the tunable impedance circuit, to enable an equivalent load impedance of the class-E power amplifier to match one of the N1 target equivalent load impedances.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

A power amplifying apparatus includes a radio frequency (RF) power amplifier, a supply modulating unit, a phase shifting unit, and an envelope shaping unit. The RF power amplifier receives an input RF signal and outputs an amplified RF signal. The supply modulating unit provides the RF power amplifier with a supply voltage which varies with an original envelope of the input RF signal. The phase shifting unit receives a control signal and shifts a phase of the input RF signal to be inputted to the RF power amplifier by a shift amount which varies with the control signal. The envelope shaping unit receives the original envelope and provides the phase shifting unit with the control signal which varies with the original envelope.

RF communications circuitry, which includes a first RF filter structure and RF detection circuitry, is disclosed. The first RF filter structure includes a first group of RF resonators, which include a first pair of weakly coupled RF resonators coupled to a signal path of a first RF signal. One of the first group of RF resonators provides a first sampled RF signal. The RF detection circuitry detects the first sampled RF signal to provide a first detected signal. The first RF filter structure adjusts a first filtering characteristic of the first RF filter structure based on the first detected signal.

A Doherty amplifier circuit having a tunable impedance and phase (“TIP”) circuit to provide an adjustable alpha factor, which allows for a selection of power added efficiency (PAE) curves that are useful for applications having different modulations or to meet other criteria. Embodiments include a Doherty amplifier having a TIP circuit that provides for tunability of the impedance Z.sub.INV (resulting in an adjustable alpha factor) while maintaining the phase of the output of the carrier amplifier at 90° (for a selected polarity) ±a low phase variation. Embodiments of the TIP circuit include one or more series-connected TIP cells comprising at least one TIP circuit combined with a tunable phase adjustment circuit. In operation, when the impedance of a TIP cell is adjusted, adjustments within the cell are also made to provide a phase shift correction back towards 90° (at the selected polarity).

An electronic circuit includes a differential output circuit that produces a differential output signal at a differential output. A primary winding of a balun has a first balun terminal coupled to a first differential output terminal, and a second balun terminal coupled to a second differential output terminal. A configurable harmonic reduction circuit includes first and second configurable shunt capacitance circuits coupled between the first differential output terminal or the second differential output terminal, respectively, and a ground reference node. A control circuit receives tuning data associated with a calibrated tuning state. The tuning data indicates a first and second calibrated capacitance values, which are unequal, for the first and second configurable shunt capacitance circuits, respectively. The control circuit controls the first configurable shunt capacitance circuit to have the first calibrated capacitance value, and controls the second configurable shunt capacitance circuit to have the second calibrated capacitance value.

A Doherty amplifier circuit having a tunable impedance and phase (“TIP”) circuit to provide an adjustable alpha factor, which allows for a selection of power added efficiency (PAE) curves that are useful for applications having different modulations or to meet other criteria. Embodiments include a Doherty amplifier having a TIP circuit that provides for tunability of the impedance Z.sub.INV (resulting in an adjustable alpha factor) while maintaining the phase of the output of the carrier amplifier at 90° (for a selected polarity)±a low phase variation. Embodiments of the TIP circuit include one or more series-connected TIP cells comprising at least one TIP circuit combined with a tunable phase adjustment circuit. In operation, when the impedance of a TIP cell is adjusted, adjustments within the cell are also made to provide a phase shift correction back towards 90° (at the selected polarity).

Processes and systems for producing glass fibers having regions devoid of glass using submerged combustion melters, including feeding a vitrifiable feed material into a feed inlet of a melting zone of a melter vessel, and heating the vitrifiable material with at least one burner directing combustion products of an oxidant and a first fuel into the melting zone under a level of the molten material in the zone. One or more of the burners is configured to impart heat and turbulence to the molten material, producing a turbulent molten material comprising a plurality of bubbles suspended in the molten material, the bubbles comprising at least some of the combustion products, and optionally other gas species introduced by the burners. The molten material and bubbles are drawn through a bushing fluidly connected to a forehearth to produce a glass fiber comprising a plurality of interior regions substantially devoid of glass.