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.

Various embodiments provide systems, devices, and methods for a multi-core digital power amplifier with an unbalanced power combiner. In one example, two or more cores are combined with a transformer section that has a first coupling coefficient and another two or more cores are combined with a second transformer section that has a second coupling coefficient that is different than the first coupling coefficient. The outputs of different cores may be cross-coupled with the primary inductors of the transformers. The digital power amplifier may provide an output power that is flat over a relatively wide operating range. Other embodiments may be described and claimed.

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.

Examples of the disclosure include a wireless device comprising a power amplifier configured to output a balanced amplified signal, an antenna configured to transmit and receive signals, a balun coupled to the power amplifier and the antenna, and being configured to receive the balanced amplified signal and output, based on the balanced amplified signal, an unbalanced amplified signal to the antenna, and at least one capacitor coupled in series between the power amplifier and the balun.

A first transmission line and a second transmission line that are connected in series to each other are disposed at different positions in a thickness direction of a substrate. A third transmission line is disposed between the first transmission line and the second transmission line in the thickness direction of the substrate. The third transmission line includes a first end portion connected to one end portion of the first transmission line, and a second end portion that is AC-grounded. The first transmission line and the second transmission line are electromagnetically coupled to the third transmission line.

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.

Multiple example valve amplifiers are provided. A first example valve amplifier is provided which comprises (i) a valve power amplifier switchable between a high-power mode and a low-power mode and (ii) a loudspeaker simulator circuit, the valve amplifier being configured such that the valve power amplifier drives the loudspeaker simulator circuit in the low-power mode. A second example valve amplifier is provided which comprises a switched-mode power supply, SMPS, system), the SMPS system comprising (i) an SMPS and (ii) circuitry configured to enable an output impedance of the SMPS to be switched between first and second output impedances, the first output impedance being lower than the second output impedance.

Low noise amplifiers (LNAs) with low noise figure are provided. In certain embodiments, an LNA includes a single-ended LNA stage including an input for receiving a single-ended input signal from an antenna and an output for providing a single-ended amplified signal, a balun for converting the single-ended amplified signal to a differential signal, and a variable gain differential amplification stage for amplifying the differential signal from the balun. Implementing the LNA in this manner provides low noise figure, high gain, flexibility in controlling gain, and less sensitivity to ground/supply impedance.

A peak detector includes an asymmetrical latch having a first input and a second input; and a CMOS converter having a first input coupled to a first output of the asymmetrical latch, a second input coupled to a second output of the asymmetrical latch, and an output.