Apparatus and methods for bias switching of power amplifiers are provided herein. In certain configurations, a power amplifier system includes a power amplifier that provides amplification to a radio frequency (RF) signal, a power management circuit that controls a voltage level of a supply voltage of the power amplifier, and a bias control circuit that biases the power amplifier. The power management circuit is operable in multiple supply control modes, such as an average power tracking (APT) mode and an envelope tracking (ET) mode. The bias control circuit is configured to switch a bias of the power amplifier based on the supply control mode of the power management circuit.

Systems, devices and methods related to multi-band power amplifier. In some embodiments, a power amplifier module includes a power amplifier having an output stage and configured to receive a signal. The power amplifier module also includes a first programmable harmonic termination circuit in electrical communication with the output stage of the power amplifier. The first programmable harmonic termination circuit includes a first plurality of capacitors and a first plurality of switches, with at least one of the first plurality of capacitors being in electrical communication with at least one of the first plurality of switches. The power amplifier module further includes a controller configured to modify a configuration of the first plurality of switches of the first programmable harmonic termination circuit based at least in part on a second harmonic frequency of the signal.

Systems, devices and methods related to multi-band power amplifier. In some embodiments, a power amplifier module includes a power amplifier having an output stage and configured to receive a signal. The power amplifier module also includes a first programmable harmonic termination circuit in electrical communication with the output stage of the power amplifier. The first programmable harmonic termination circuit includes a first plurality of capacitors and a first plurality of switches, with at least one of the first plurality of capacitors being in electrical communication with at least one of the first plurality of switches. The power amplifier module further includes a controller configured to modify a configuration of the first plurality of switches of the first programmable harmonic termination circuit based at least in part on a second harmonic frequency of the signal.

Devices and methods for operating a charge pump. In some implementations, a charge pump module includes a clock circuit configured generate to a first clock signal and a second clock signal, the first clock signal having a lower frequency than the second clock signal. The charge pump module also includes a driving circuit configured to generate a first set of clock signals based on the first clock signal and a second set of clock signals based on the second clock signal, the driving circuit coupled to the clock circuit. The charge pump module further includes a charge pump core including a set of capacitances, the charge pump core configured to charge the set of capacitances based the first set of clock signals and the second set of clock signals.

Devices and methods for operating a charge pump. In some implementations, a charge pump module includes a clock circuit configured generate to a first clock signal and a second clock signal, the first clock signal having a lower frequency than the second clock signal. The charge pump module also includes a driving circuit configured to generate a first set of clock signals based on the first clock signal and a second set of clock signals based on the second clock signal, the driving circuit coupled to the clock circuit. The charge pump module further includes a charge pump core including a set of capacitances, the charge pump core configured to charge the set of capacitances based the first set of clock signals and the second set of clock signals.

A power amplification system with shared common base biasing is disclosed. A method for power amplification at a controller of a power amplification system comprising a plurality of cascode amplifier sections can include receiving a band select signal indicative of one or more frequency bands of a radio-frequency input signal to be amplified and transmitted. The method may further include biasing a common base stage of each of the plurality of cascode amplifier sections, and biasing a common emitter stage of a subset of the plurality of cascode amplifier sections.

A power amplification system with shared common base biasing is disclosed. A method for power amplification at a controller of a power amplification system comprising a plurality of cascode amplifier sections can include receiving a band select signal indicative of one or more frequency bands of a radio-frequency input signal to be amplified and transmitted. The method may further include biasing a common base stage of each of the plurality of cascode amplifier sections, and biasing a common emitter stage of a subset of the plurality of cascode amplifier sections.

The present disclosure relates to devices and methods for detecting and preventing occurrence of a saturation state in a power amplifier. A power amplifier module can include a power amplifier including a cascode transistor pair. The cascode transistor pair can include a first transistor and a second transistor. The power amplifier module can include a current comparator configured to compare a first base current of the first transistor and a second base current of the second transistor to obtain a comparison value. The power amplifier module can include a saturation controller configured to supply a reference signal to an impedance matching network based on the comparison value. The impedance matching network can be configured to modify a load impedance of a load line in electrical communication with the power amplifier based at least in part on the reference signal.

The present disclosure relates to devices and methods for detecting and preventing occurrence of a saturation state in a power amplifier. A power amplifier module can include a power amplifier including a cascode transistor pair. The cascode transistor pair can include a first transistor and a second transistor. The power amplifier module can include a current comparator configured to compare a first base current of the first transistor and a second base current of the second transistor to obtain a comparison value. The power amplifier module can include a saturation controller configured to supply a reference signal to an impedance matching network based on the comparison value. The impedance matching network can be configured to modify a load impedance of a load line in electrical communication with the power amplifier based at least in part on the reference signal.

Systems and methods related to power amplification and power supply control. A power amplification control system can include an interface configured to receive a transceiver control signal from a transceiver. The power amplification control system can include a power amplifier control component configured to generate a power amplifier control signal based on the transceiver control signal from the transceiver and a power supply control component configured to generate a power supply control signal based on the transceiver control signal from the transceiver and to generate the power supply control signal based on a local control signal from the power amplifier control component.