A Doherty amplifier includes: a first amplifying element to amplify a first signal; a second amplifying element to amplify a second signal having a phase difference with the first signal; a first transmission line connected to an output terminal of the first amplifying element; and a second transmission line connected to an output terminal of the second amplifying element, wherein the first transmission line and the second transmission line are equal to each other in characteristic impedance, the phase difference between the first signal and the second signal is not equal to a difference in electrical length between the second transmission line and the first transmission line, and the first signal having passed through the first transmission line and the second signal having passed through the second transmission line are subjected to different phase synthesis.

RF transistor amplifiers include an RF transistor amplifier die having a Group III nitride-based semiconductor layer structure and a plurality of gate terminals, a plurality of drain terminals, and at least one source terminal that are each on an upper surface of the semiconductor layer structure, an interconnect structure on an upper surface of the RF transistor amplifier die, and a coupling element between the RF transistor amplifier die and the interconnect structure that electrically connects the gate terminals, the drain terminals and the source terminal to the interconnect structure.

A radio frequency module includes: a first low-noise amplifier including a first amplification element as an input stage and a second amplification element as an output stage; a second low-noise amplifier including a third amplification element as an input stage and the second amplification element as an output stage, the third amplification element being different from the first amplification element; a first matching circuit connected to an input terminal of the first low-noise amplifier; and a module substrate including a first principal surface and a second principal surface opposite to each other, wherein the first amplification element is disposed on one of the first principal surface and the second principal surface, and the first matching circuit is disposed on the other of the first principal surface and the second principal surface.

Apparatus including a first transmission line for transmitting radio frequency, RF, signals and at least one RF device including at least one active semiconductor device for processing RF signals, wherein said at least one RF device is coupled to said first transmission line, and wherein said first transmission line includes an electro-chromic, EC, material a permittivity of which can be controlled by applying a first control voltage to said first transmission line.

An RF amplifier utilizes first and second main amplifiers in a balanced amplifier configuration with first and second auxiliary amplifiers connected in parallel across the first and second main amplifiers, respectively. The main and the auxiliary amplifiers are biased such that the third-order nonlinearity components in the combined output current are reduced. A common or independent bias control circuit(s) control(s) the DC operating bias of the auxiliary amplifiers and establishes DC operating points on curves representing third-order nonlinear components within the drain current having a positive slope (opposite to the corresponding slope of the main amplifiers). This results in reduction of overall third-order nonlinear components in combined currents at the output. In another embodiment, a phase shift of an input to one auxiliary amplifier is used to provide a peak in minimization at a frequency associated with the phase shift.

A Doherty power amplifier circuit having a main power amplification device, an auxiliary power amplification device arranged in parallel with the main power amplification device, and a load modulation circuit comprising a harmonic injection circuit connected with respective outputs of the main power amplification device and the auxiliary power amplification device. The harmonic injection circuit is arranged to transfer harmonic components generated at the main power amplification device to the auxiliary power amplification device and harmonic components generated at the auxiliary power amplification device to the main power amplification device, when both the main and auxiliary power amplification devices are operating, for modulating the respective outputs of the main power amplification device and the auxiliary power amplification device.

An amplifier that is configured to amplify an RF signal includes a power combiner circuit. The power combiner circuit includes a first branch connected between a first RF input port and a summing node and a second branch connected between a second RF input port and the summing node. Each of the first and second branches includes an impedance inverter. The Chireix combiner is configured to present a Chireix load modulated impedance response to the first and second RF input ports. The power combiner circuit further includes compensation elements being configured to at least partially compensate for a reactance of the Chireix combiner circuit in a Doherty amplifier mode in which a signal is applied to the first RF input port and the second RF input port is electrically open.

Described herein is a single-input hybrid Doherty power amplifier (PA). Unlike the conventional 214 Doherty PA inverter which only performs the correct load modulation at its center frequency, the hybrid Doherty PA (HDω-PA) combiner network achieves a wideband load modulation using the frequency dependence of the electrical length of the output combiner lines versus frequency for sliding the PA mode of operation. A modified theory is presented herein to allow for a single-input PA implementation. In this design, the outphasing angle is only changing with frequency and not the input power. A transmission line phase shifter is used to provide the correct frequency-dependent input phase offset ensuring the correct wideband load modulation performed by the output combiner

An RF power amplifier circuit includes a power divider, multiple power amplification circuits and a power combiner that cooperatively perform power amplification on an RF input signal so as to output an RF output signal, and an impedance conversion circuit that has a circuit terminal coupled to one of the power divider and the power combiner which has a microstrip structure, and that is configured such that a conversion impedance, which is an impedance seen into the impedance conversion circuit from the circuit terminal, matches an impedance seen into the power divider or the power combiner from the circuit terminal. The microstrip structure has a physical length associated with the conversion impedance.

The present disclosure includes dynamic power divider circuits and methods. In one embodiment, a dynamic power divider includes first and second quarter wave lines that receive an input signal and produce first and second signal on second terminals of the lines. Dynamic power division of the input signal uses a variable impedance circuit between the second terminal of the first quarter wave line and the second terminal of the second quarter wave line. The variable impedance may reduce impedance between two output paths as the input signal power increases or increase impedance between the output paths as the input signal power decreases.