A power amplifier circuit includes first and second transistors and a first voltage output circuit. A radio frequency signal is input into a base of the first transistor. The first voltage output circuit outputs a first voltage in accordance with a power supply voltage. The first voltage is supplied to a base or a gate of the second transistor. An emitter or a source of the second transistor is connected to a collector of the first transistor. A first amplified signal generated by amplifying the radio frequency signal is output from a collector or a drain of the second transistor.

Switchable base feed circuit for radio-frequency (RF) power amplifiers. In some embodiments, an RF power amplifier (PA) circuit can include a transistor having a base, a collector, and an emitter, with the transistor being configured to amplify an RF signal. The PA circuit can further include a bias circuit configured to provide a base bias signal to the base of the transistor. The PA circuit can further include a switchable base feed circuit implemented between the bias circuit and the base of the transistor. The switchable base feed circuit can be configured to provide a plurality of different resistance values for the base bias signal between the bias circuit and the base of the transistor. Such a PA circuit can be implemented in products such as a die, a module, and a wireless device.

Disclosed herein are power amplification systems that are dynamically biased based on a signal indicative of an envelope of the signal being amplified. The power amplification systems include a power amplifier configured to amplify an input radio-frequency (RF) signal to generate an output RF signal when biased by a biasing signal. The power amplification systems also include a bias component configured to generate the biasing signal based on an envelope signal indicative of an envelope of the input RF signal. The biasing signal can improve or enhance the linearity of the power amplification systems.

A power amplifier system having a power amplifier stage with dynamic bias circuitry is disclosed. Also included is bias control circuitry having a compression sensor having a sensor input coupled to a RF signal output and a sensor output, wherein the compression sensor is configured to generate a gain deviation signal in response to a sensed deviation from a flat gain profile of the power amplifier stage. Further included is a bias driver that is configured to drive dynamic bias circuitry to adjust bias to the power amplifier stage to maintain the flat gain profile in response to the gain deviation signal.

A method and system for linearizing a Radio Frequency Power Amplifier (RFPA) is disclosed. The method comprises calibrating signals in the RFPA to linearize the RFPA, using at least one of a first signal, a second signal, a third signal, and a fourth signal. The first signal is generated corresponding to ambient temperature. The second signal is generated corresponding to process corner of transistors in the RFPA. The third signal is generated corresponding to power supply voltage. The fourth signal is generated by feeding back output of the RFPA.

A power amplifier apparatus includes: an amplifier configured to amplify an input signal; a sensing circuit connected to the amplifier and configured to sense a bias of the amplifier; and a biasing circuit connected to the sensing circuit and configured to provide a biasing current to the amplifier, wherein the sensing circuit is configured to change the biasing current based on the bias of the amplifier.

An apparatus and a method for improving nonlinearity of a power amplifier in a wireless communication system are provided. A transmission apparatus in a wireless communication system comprises: at least one processor; a transceiver; and an amplifier for amplifying a signal provided from the transceiver, wherein if a power of a signal inputted into the transceiver is smaller than a reference value, the transceiver attenuates the power of the signal based on a gain compensation value corresponding to the power of the signal.

The invention relates to a broadband high power amplifier that comprises a signal input adapted to receive an input signal, at least one amplifier stage adapted to amplify the received input signal, a signal output adapted to output the signal amplified by the at least one amplifier stage as an output signal, a monitoring unit adapted to monitor signal characteristics of the input signal and the output signal and a control unit adapted to operate the at least one amplifier stage at an optimal operating point depending on the current signal characteristics monitored by said monitoring unit.

A power amplification apparatus which is a Doherty power amplification apparatus includes a main amplifier configured to amplify an input signal, and an auxiliary amplifier configured to amplify the input signal when a level of the input signal is higher than a predetermined level. The power amplification apparatus includes an auxiliary amplifier threshold value shift detector configured to detect a threshold value shift in the auxiliary amplifier; and an auxiliary amplifier bias voltage adjustment circuit configured to adjust a bias voltage of the auxiliary amplifier based on the detected threshold value shift in the auxiliary amplifier.

A low noise amplifier (LNA) system having a constant noise factor (Const-NF) mode and a constant third-order intercept (Const-IP3) mode is disclosed. The LNA system includes an LNA core and a trade-off bias network coupled to the LNA core to selectably bias the LNA core to realize the Const-NF mode and the Const-IP3 mode. The trade-off bias network is made up of selectable Const-NF circuitry and selectable Const-IP3 circuitry. The LNA system further includes a bias switching controller that is configured to enable the selectable Const-NF circuitry and disable the selectable Const-IP3 circuitry to select the Const-NF mode in response to a first condition and to disable the selectable Const-NF circuitry and enable the selectable Const-IP3 circuitry to select the Const-IP3 mode in response to a second condition.