The present disclosure provides a power amplifier circuit capable of suppressing the occurrence of noises while enabling control of an output power level. The power amplifier circuit includes a first transistor that amplifies a first signal; a bias circuit that supplies a bias current or voltage based on a control signal to the first transistor; a second transistor to which a control current based on the control signal is supplied, which has an emitter or a source thereof connected to a collector or a drain of the first transistor, and from which a second signal obtained by amplifying the first signal is output; and a first feedback circuit provided between the collector or the drain of the second transistor and the base or the gate of the second transistor.

Power amplification system with adjustable common base bias. A power amplification system can include a cascode amplifier coupled to a radio-frequency input signal and coupled to a radio-frequency output. The power amplification system can further include a biasing component configured to apply one or more biasing signals to the cascode amplifier, the biasing component including a bias controller and one or more bias components. Each respective bias component may be coupled to a respective bias transistor.

An outphasing amplifier includes a first class-E power amplifier having an output coupled to a first conductor and an input receiving a first RF drive signal. A first reactive element is coupled between the first conductor and a second conductor. A second reactive element is coupled between the second conductor and a third conductor. A second class-E power amplifier includes an output coupled to a fourth conductor and an input coupled to a second RF drive signal, a third reactive element coupled between the second and fourth conductors. Outputs of the first and second power amplifiers are combined by the first, second and third reactive elements to produce an output current in a load. An efficiency enhancement circuit is coupled between the first and fourth conductors to improve power efficiency at back-off power levels. Power enhancement circuits are coupled to the first and fourth conductors, respectively.

The embodiments described herein include amplifier devices that are typically used in radio frequency (RF) applications. The amplifier devices described herein use a plurality of phase shifters to provide selectable back-off power. Specifically, the amplifier devices can be implemented with phase shifters having phase shift values selected to provide a desired back-off power.

Provided is a power amplification module that supports a plurality of communication systems. The power amplification module includes: two power amplifiers that can be selectively connected in parallel with each other; a switch that, in accordance with one communication system selected from among the plurality of communication systems, selects one power amplifier that is to operate by itself from among the two power amplifiers or selects the two power amplifiers and connects the two power amplifiers in parallel with each other; and a phase correction circuit that, when the two power amplifiers are both selected, corrects a phase difference by being selectively connected between the outputs of the two selected power amplifiers such that a phase difference is not generated between the output signals of the two selected power amplifiers.

A wireless communication device includes an amplifier block amplifying a radio frequency (RF) input signal. The amplifier block includes: a first amplification unit and a second amplification unit. The first amplification unit amplifies the RF input signal to generate a first RF amplified signal including a first non-linearity factor and a second RF amplified signal including a second non-linearity factor, and combines the first and second RF signals to generate a third RF amplified signal. The second amplification unit receives and amplifies the third RF amplified signal to output an RF output signal corresponding to the at least one carrier.

Circuits, devices and methods related to power amplification without matching network. In some embodiments, a power amplification circuit can include a power amplifier configured to amplify a signal. The power amplification circuit can further include a filter coupled to the power amplifier. The power amplifier can be further configured to operate with an impedance that is approximately same as an impedance of the filter.

Doherty power amplifier having high supply voltage. In some embodiments, a power amplification system can include a supply system configured to provide a high-voltage supply signal, and a Doherty power amplifier having an input splitter configured to receive and split a signal into a carrier amplifier and a peaking amplifier. The Doherty power amplifier can further include a combiner configured to combine amplified signals from the carrier and peaking amplifiers to provide an output signal. The Doherty power amplifier can be configured to receive the high-voltage supply signal for operation of the carrier and peaking amplifiers. The power amplification system can further include an output path configured to couple the combiner to a filter. The Doherty power amplifier can have an impedance substantially the same as an impedance of the filter when operated with the high-voltage supply signal.

A voltage-to-current converter that reduces third harmonic distortion. An amplifier includes an input stage. The input stage includes a first voltage-to-current conversion stage and a second voltage-to-current conversion stage. The first voltage-to-current conversion stage is configured to provide an input to output gain with compressive nonlinearity. The second voltage-to-current stage is cascaded with the first voltage-to-current conversion stage. An input of the second voltage-to-current stage is connected to an output of the first voltage-to-current conversion stage. The second voltage-to-current conversion stage is configured to provide an input to output gain with expansive nonlinearity.

A power amplifier includes a carrier amplifier that operates from when an input signal is small, a peak amplifier that starts to operate when the input signal becomes large, a phase adjusting circuit that adjusts phases of an output of the carrier amplifier and an output of the peak amplifier, an impedance transforming line that transforms a load of the carrier amplifier when the input signal is small, and has a characteristic impedance close to an optimum load impedance of the carrier amplifier, and a circuit that is arranged between the output of the carrier amplifier and the impedance transforming line and reduces an output capacitance of the carrier amplifier.