A power amplifier comprises a first amplification stage having an input terminal receiving a radio frequency (RF) signal to be amplified and having a first coupling unit, a second amplification stage outputting an amplified radio frequency signal and having a second coupling unit and a third coupling unit providing RF feedback to the input terminal of the first amplification stage through an RF feedback path, the second coupling unit being coupled to the first coupling unit, and the third coupling unit being coupled to the first coupling unit.

A power supply switch circuit includes a first switch configured to supply a first power supply voltage to a power supply terminal of a power amplifier, a control voltage generator configured to compare a first voltage of the power supply terminal with a predetermined first reference voltage to generate a first control voltage higher than the first power supply voltage, and a switch controller configured to use the first control voltage to generate a switching driving signal controlling the first switch.

A power supply switch circuit includes: a first switch to switch supply of a first power supply voltage to a power supply terminal of a power amplifier; a control voltage generator to generate a first control voltage through a charge pump operation, and to control the charge pump operation by comparing the first power supply voltage to a first voltage, which is a voltage of the power supply terminal; and a switch controller to generate a switching driving signal to control the first switch using the first control voltage.

The present power amplifier linearizing module linearizes operation of a power amplifier and operates in parametrizing mode and operation mode. A processing module executes a feed-forward transfer functions set, which includes at least: a transfer function P and a summing function. The transfer function P derives a change signal ΔV.sub.a relative to the control signal component received and the summing function summing the incremental change signal ΔV.sub.a to an input signal to generate an adjusted input signal. A transfer function G uses the adjusted input signal to generate an RF signal representative of the amplifying of the adjusted input signal based on the control signal component. The processing module determines a linearizing control signal component based on the generated RF signal representative.

A system and method which includes receiving an input signal and providing, by an amplifier circuit, an output signal in response to the input signal, the output signal having an envelope. An envelope detection signal corresponding to the envelope of the output signal is generated. A bias current provided to an amplifier circuit is adjusted based upon the envelope detection signal. The amplifier circuit includes an amplifier and a transformer, the transformer being configured to establish a magnetically coupled feedback loop from an output of the amplifier to an input of the amplifier.

A power management integrated circuit (PMIC) can improve the ramp up speed of a boost converter with the inclusion of a controllable switch that may modify the connection of an output capacitor to reduce the ramp time as the output voltage is ramping to a desired boost setpoint. The switch may be controlled using jump start logic to switch a first plate or terminal of the output capacitor from a ground connection to a voltage supply connection. Once a threshold voltage is reached, the first plate of the capacitor may be switched from the supply voltage to ground. In certain cases, by switching the connection of the output capacitor between ground and a supply voltage based on one or more threshold voltages or a boost setpoint, the time to ramp from an initial voltage to a desired boost setpoint may be reduced.

A power amplifier circuit includes a transistor having a base to which a radio frequency signal is input and a collector to which a power supply voltage that varies in accordance with an envelope of amplitude of the radio frequency signal is supplied and from which an amplified signal obtained by amplifying the radio frequency signal is output; a first termination circuit provided at a stage subsequent to the transistor and configured to attenuate a harmonic component of the amplified signal; and a second termination circuit provided at the stage subsequent to the transistor and configured to attenuate a harmonic component of the amplified signal. The first termination circuit and the second termination circuit have a property of resonating for a radio frequency signal having a frequency between a frequency of a second harmonic component and a frequency of a third harmonic component.

A radio frequency circuit includes a power amplifier configured to selectively amplify one of a first radio frequency signal and a second radio frequency signal that have different bandwidths, and when the first radio frequency signal is input to the power amplifier, a first bias signal is applied to the power amplifier, and when the second radio frequency signal is input to the power amplifier, a second bias signal different from the first bias signal is applied to the power amplifier.

Apparatus and methods for power amplifier output matching is disclosed. In one aspect, there is provided an output matching circuit including an input configured to receive an amplified radio frequency signal from a power amplifier, a first output, and a second output. The output matching circuit further includes a first matching circuit electrically connected between the input of the output matching circuit and the first output, the first matching circuit configured to suppress harmonics of a fundamental frequency of the amplified radio frequency signal when the amplified radio frequency signal is within a first band. The output matching circuit further includes a second matching circuit electrically connected between the input of the output matching circuit and the second output, the second matching circuit configured to suppress harmonics of the fundamental frequency of the amplified radio frequency signal when the amplified radio frequency signal is within a second band different from the first band.

An envelope tracking (ET) radio frequency (RF) front-end circuit is provided. The ET RF front-end circuit includes an ET integrated circuit(s) (ETIC(s)), a local transceiver circuit, a target voltage circuit(s), and a number of power amplifiers. The local transceiver circuit receives an input signal(s) from a coupled baseband transceiver and generates a number of RF signals. The target voltage circuit(s) generates a time-variant ET target voltage(s) based on the input signal(s). The ETIC(s) generates multiple ET voltages based on the time-variant ET target voltage(s). The power amplifiers amplify the RF signals based on the ET voltages. Given that the time-variant ET target voltage(s) is generated inside the self-contained ET RF front-end circuit, it is possible to reduce distortion in the time-variant ET target voltage(s), thus helping to improve operating efficiency of the power amplifiers, especially when the RF signals are modulated with a higher modulation bandwidth (e.g., ≥200 MHz).