The present disclosure provides a RF power amplifier and a method for manufacturing a Doherty power amplifier. The RF power amplifier includes at least one transistor, a harmonic termination circuit, and an impedance inverter. The harmonic termination circuit has one terminal directly connected to the drain electrode of the transistor and contributes as a part of a harmonic matching network for the transistor at the second harmonic and/or the third harmonic of the fundamental frequency. The impedance inverter is configured to perform impedance inversion of a static load or a modulated load at the fundamental frequency without affected by the harmonic termination circuit.

Provided is a high-gain amplifier based on double-gain boosting including a first gain amplification unit including a first amplifier, a second amplifier, and a an interstage matching network connected between the first amplifier and the second amplifier and performing primary amplification; and a second gain amplification unit connected in parallel with the first gain amplification unit and performing secondary boosting.

A harmonic processing circuit includes a first inductor having a first end connected to a connection line connected between an amplifier and an impedance matching circuit, and a second end connected to a first node, a first transmission line having a third end connected to the first node and a fourth end connected to a second node, and a parallel resonant circuit having a fifth end connected to the second node and a sixth end connected to a reference potential, wherein a second inductor and a first capacitor are connected in parallel between the fifth end and the sixth end, wherein when the first inductor is viewed from the connection line, an impedance at a frequency of a fundamental wave amplified by the amplifier is larger than an impedance at a frequency of a second harmonic having twice the frequency of the fundamental wave.

A power amplifier circuit comprising a transistor for receiving a signal to be amplified at an input and for outputting an amplified signal at an output; a modulated power supply connected to the transistor output; and a resistive element connected at the transistor output such that a low impedance is maintained at the transistor output across a range of operational frequencies.

A power amplifier circuit comprising a transistor for receiving a signal to be amplified at an input and for outputting an amplified signal at an output; a modulated power supply connected to the transistor output; and a resistive element connected at the transistor output such that a low impedance is maintained at the transistor output across a range of operational frequencies.

Optimized impedance characteristics of a variable impedance device causes the apparatus to transmit wireless signals with minimal out-of-band transmission at an optimized efficiency of the power amplifier. The variation of impedance characteristics of an antenna cause a change in the coefficients of a mapping function. The relatively fast variations to the power supply voltage of a power amplifier are applied to the mapping function to generate control signals which vary the impedance characteristics of a variable impedance device. The output of the mapping function includes control signals that control optimized impedance characteristics of a variable impedance device as a function of the variation of the supply voltage to a power amplifier. The coefficients of the mapping function may be regularly determined based on a comparison of out-of-band power and in-band power transmitted by an antenna.

Various envelope tracking amplifiers are presented that can be switched between an ET (envelope tracking) mode and a non-ET mode. Switches and/or tunable components are utilized in constructing the envelope tracking amplifiers that can be switched between the ET mode and the non-ET mode.

Various envelope tracking amplifiers are presented that can be switched between an ET (envelope tracking) mode and a non-ET mode. Switches and/or tunable components are utilized in constructing the envelope tracking amplifiers that can be switched between the ET mode and the non-ET mode.

Aspects of this disclosure relate to a cascode circuit electrically coupled between an amplifier configured to amplify a radio frequency (RF) signal and different loads. The cascode circuit can function as a switch to selectively provide an output from the amplifier to a number of different loads. In certain embodiments, the cascode circuit can be electrically coupled between different stages of a multi-stage power amplifier. For instance, the amplifier can be a first stage of the multi-stage power amplifier and the different loads can include different power amplifier transistors of a second stage of the multi-stage amplifier. The cascode circuit can be implemented by bipolar transistors according to certain embodiments.

Aspects of this disclosure relate to a cascode circuit electrically coupled between an amplifier configured to amplify a radio frequency (RF) signal and different loads. The cascode circuit can function as a switch to selectively provide an output from the amplifier to a number of different loads. In certain embodiments, the cascode circuit can be electrically coupled between different stages of a multi-stage power amplifier. For instance, the amplifier can be a first stage of the multi-stage power amplifier and the different loads can include different power amplifier transistors of a second stage of the multi-stage amplifier. The cascode circuit can be implemented by bipolar transistors according to certain embodiments.