A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.

A power amplifying circuit includes a first input terminal applied with a first bias voltage, a first amplifying circuit generating a first output signal and a second output signal according to an input signal and a first matching circuit combining the first output signal and the second output signal to generate an output signal. The first amplifying circuit includes a first transistor having a first electrode coupled to the first input terminal and a second electrode applied with a second bias voltage and a second transistor having a first electrode s coupled to the first input terminal and a second electrode applied with a third bias voltage. The first transistor generates the first output signal according to the first bias voltage and the second bias voltage. The second transistor generates the second output signal according to the first bias voltage and the third bias voltage.

A Doherty amplifier comprising: a main-power-amplifier having a main-amp-output-terminal; a peaking-power-amplifier having a peaking-amp-output-terminal; a combining node; a main-output-impedance-inverter connected between the main-amp-output-terminal and the combining node; and a transformer connected between the peaking-amp-output-terminal and the combining node.

A power amplifier module includes a first substrate and a second substrate, at least part of the second substrate being disposed in a region overlapping the first substrate. The second substrate includes a first amplifier circuit and a second amplifier circuit. The first substrate includes a first transformer including a primary winding having a first end and a second end and a secondary winding having a first end and a second end; a second transformer including a primary winding having a first end and a second end and a secondary winding having a first end and a second end; and multiple first conductors disposed in a row between the first transformer and the second transformer, each of the multiple first conductors extending from the wiring layer on a first main surface to the wiring layer on a second main surface of the substrate.

Disclosed is a reconfigurable power amplifier having a 2.sup.N−1 number of input-side reconfigurable quadrature couplers connected in a tree structure, wherein a 2.sup.(N−1) number of the input-side reconfigurable quadrature couplers have coupler output terminals, and a root of the tree structure is one of the input-side reconfigurable quadrature couplers having a main input terminal. Also included is a 2.sup.N−1 number of output-side reconfigurable quadrature couplers connected in a tree structure, wherein a 2.sup.(N−1) number of the output-side reconfigurable quadrature couplers have coupler input terminals, and a root of the tree structure is one of the output-side reconfigurable quadrature couplers having a main output terminal. Further included is a 2.sup.N number of constituent amplifiers divided into amplifier pairs having amplifier input terminals connected to corresponding ones of the coupler output terminals and having amplifier output terminals coupled to corresponding ones of the coupler input terminals.

A push-pull radio frequency power amplifier includes a coupling feedback circuit, a drive stage circuit and a power output stage circuit, in which the coupling feedback circuit is connected with the drive stage circuit and/or the power output stage circuit; the coupling feedback circuit is configured to generate an alternating voltage at an input end of a first transistor and/or an input end of a push-pull transistor; when the alternating voltage and a voltage at the input end are in a same direction, a positive feedback of an input signal at the input end is achieved; and the first transistor represents a transistor in the drive stage circuit and the push-pull transistor represents a second transistor and a third transistor that form a push-pull structure in the power output stage circuit.

Amplifiers, amplification circuits, and phase shifters, for example, for flexibly adjusting an output phase to thereby meet a requirement of a constant phase on a link in a communications field, are provided. In one aspect, an amplifier includes first, second, and third MOS transistors. The first MOS transistor includes a gate separately coupled to a signal input end and a bias voltage input end, a source coupled to a power supply, and a drain separately coupled to sources of the second and third MOS transistors. A drain of the third MOS transistor is coupled to a ground, and a drain of the second MOS transistor is coupled to a signal output end. The bias voltage input end is configured to receive a bias voltage to adjust a phase difference between an input signal at the signal input end and an output signal at the signal output end.

Data isolators are described. The data isolators include a differential receiver having cross-coupled single-ended amplifiers. The single-ended amplifiers may be referenced to a time-varying reference potential. The cross-coupling of the single-ended amplifiers may provide high speed, low power consumption operation of the data isolator.

An apparatus includes a transformer including a first inductor, a second inductor, and a third inductor. The apparatus also includes a power amplifier having an output coupled to the first inductor, a low-noise amplifier having an input coupled to a first terminal of the third inductor, and a fourth inductor having a first terminal and a second terminal, wherein the second terminal of the fourth inductor is coupled to a second terminal of the third inductor. The apparatus also includes a switch coupled between the first terminal of the third inductor and the first terminal of the fourth inductor.

Provided are a matching network, an antenna circuit and an electronic device. The matching network includes a first inductor, a second inductor, and a third inductor, the first inductor having two ends serving as a pair of output terminals, the second inductor having two ends serving as a first pair of input terminals, and the third inductor having two ends serving as a second pair of input terminals, where a first coupling coefficient between the first inductor and the second inductor is greater than a second coupling coefficient between the first inductor and the third inductor. According to the matching network, the matching network can present a rather large resistance value conversion ratio even with a rather small area taken by inductors, the circuit design can be more flexible, and the signal interference can be lowered.