One example includes a device that is comprised of a pre-power amplifier, a power amplifier, a signal path, and a dynamic bias circuit. The pre-power amplifier amplifies an input signal and outputs a first amplified signal. The power amplifier receives the first amplified signal and amplifies the first amplified signal based on a dynamic bias signal to produce a second amplified signal at an output thereof. The signal path is coupled between an output of the pre-power amplifier and an input of the power amplifier. The dynamic bias circuit monitors the first amplified signal, generates the dynamic bias signal, and outputs the dynamic bias into the signal path.

Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes an error amplifier that controls a voltage level of a power amplifier supply voltage of the power amplifier based on amplifying a difference between a reference signal and an envelope signal indicating an envelope of the RF signal. The envelope tracker further includes a multi-level switching circuit that generates an error amplifier supply voltage based on sensing a current of the error amplifier, and uses the error amplifier supply voltage to power the error amplifier.

A power amplifier circuit includes a first transistor having an emitter electrically connected to a common potential, a base to which a first high-frequency signal is input, and a collector from which a third high-frequency signal is output; a second transistor having an emitter electrically connected to the common potential, a base to which a second high-frequency signal is input, and a collector from which a fourth high-frequency signal is output; a first capacitance circuit electrically connected between the collector of the second transistor and the base of the first transistor; and a second capacitance circuit electrically connected between the collector of the first transistor and the base of the second transistor.

Doherty radio frequency (RF) amplifier circuitry includes an input node, an output node, a main amplifier path, and a peaking amplifier path. The main amplifier path is coupled between the input node and the output node and includes a main amplifier. The peaking amplifier path is coupled in parallel with the main amplifier path between the input node and the output node, and includes a peaking amplifier and a peaking variable gain preamplifier between the input node and the peaking amplifier. The peaking variable gain preamplifier is configured to adjust a current provided to the peaking amplifier.

An example electronic device includes an antenna; a switching regulator; a communication chip including an amplifier, a first linear regulator operably connected to the amplifier and the switching regulator and configured to be supplied with a first voltage from the switching regulator, and a second linear regulator operably connected to the amplifier and the switching regulator and configured to be supplied with a second voltage higher than the first voltage from the switching regulator, the communication chip configured to transmit a radio-frequency signal outside of the electronic device through the antenna; and a control circuit. The control circuit is configured to produce an envelope of an input signal input to the amplifier in connection with the radio-frequency signal and to provide the produced envelope to at least one of the first linear regulator or the second linear regulator. The first linear regulator is configured to provide a third voltage corresponding to the envelope to the amplifier using the first voltage based on the envelope having a voltage in a first range. The second linear regulator is configured to provide a fourth voltage higher than the third voltage to the amplifier using the second voltage based on the voltage of the envelope being in a second range including values larger than values included in the first range.

In some embodiments, an amplifier system can include an amplifier circuit having first and second amplifiers configured to amplify respective first and second portions of an input signal. Each of the first and second amplifiers can include a cascode stage with input and output transistors arranged in a cascode configuration. The amplifier system can further include an envelope tracking bias circuit coupled to the amplifier circuit and configured to provide a bias signal to the output transistor of the cascode stage of at least one of the first and second amplifiers. The amplifier system can further include a supply circuit configured to provide a non-envelope tracking supply voltage to the output transistor of the cascode stage of the at least one of the first and second amplifiers.

A power amplifier circuit includes a power amplifier including a first transistor having a first terminal connected to a reference potential, a second terminal to which a first current and a radio-frequency signal are input, and a third terminal connected to a first power supply potential via a first inductor; a capacitor connected to the third terminal of the first transistor; a second transistor including a first terminal connected to the capacitor and the reference potential via a second inductor, a second terminal to which a second current is input and is connected to the reference potential, and a third terminal connected to the first power supply potential via a third inductor and outputs signal; and an adjustment circuit that outputs a third current corresponding to the first power supply potential or a second power supply potential to the second terminal of the second transistor.

An apparatus and method for calibrating an envelope tracking (ET) lookup table (LUT) are provided. An ET power management apparatus includes a power amplifier configured to amplify a radio frequency (RF) signal from a time-variant input power to a time-variant output power linearly related to the time-variant input power. A calibration circuit is employed to receive a time-variant output power feedback nonlinearly related to the time-variant input power, determine a linear relationship between the time-variant input power and the time-variant output power based on the time-variant output power feedback, and calibrate the ET LUT based on the determined linear relationship. As a result, it is possible to improve accuracy of the ET LUT to thereby improve operating efficiency and linearity of the power amplifier.

In some embodiments, a power supply system for a power amplifier can include a voltage converter implemented generate a first voltage at an output node, and an envelope following circuit implemented to generate and combine a second voltage with the first voltage to provide a combined output voltage for the power amplifier. The combined output voltage can have a waveform that follows one or more peaks of an envelope of a radio-frequency signal above the first voltage.

Amplifier circuits, radio communication circuits, radio communication devices, and methods provided in this disclosure. The amplifier circuit may include an amplifier configured to amplify an input signal to provide an output signal. The output signal of the amplifier may include a direct current (DC) signal. The amplifier circuit may further include a current source coupled to the amplifier. The current source may be configured to receive an electrical supply. The current source may further be configured to divide the direct current (DC) signal of the output signal based on the electrical supply.