The present invention provides a control circuit to stabilize an output power of a power amplifier. The control circuit comprises a voltage clamping loop, a current clamping loop and a loop for reducing power variation under VSWR, where the voltage clamping loop is used to clamp an output voltage of the power amplifier within a defined voltage range, the current clamping loop is used to clamp a current of the power amplifier within a defined current range, and the loop for reducing power variation under VSWR is implemented by an impedance detector to compensate the output power under VSWR variation.

A radio frequency (RF) amplification device comprises an RF amplification circuit, and a dynamic level shifter (DLS) circuit coupled between a supply voltage and the RF amplification circuit. The DLS circuit is configured to provide a first shifted voltage to the RF amplification circuit via a first diode when the supply voltage is above a first threshold voltage level. The DLS circuit is further configured to provide a second shifted voltage to the RF amplification circuit via a first shunt transistor when the supply voltage is below the first threshold voltage level, wherein the supply voltage less the second shifted voltage is less than the supply voltage less the first shifted voltage.

An electronic device includes devices such as a power source, a power amplifier, and a speaker. The electronic device may supply an adaptable output voltage to the power amplifier based on a detected operating state of the speaker. Specifically, by designing a connecting circuit between the power source and the power amplifier, when the power amplifier operates on different circuits, the power source can provide different output voltages for the power amplifier, and then provide an adaptable driving power for the speaker.

An RF amplifier comprising an input-transistor having an input-transistor-base terminal, an input-transistor-collector terminal and an input-transistor-emitter terminal; a degeneration-component connected between the input-transistor-emitter terminal and a ground terminal; and a protection-transistor having a protection-transistor-base terminal, a protection-transistor-collector terminal and a protection-transistor-emitter terminal. The input-transistor-base terminal is connected to the protection-transistor-emitter terminal, and the protection-transistor-base terminal is connected to the input-transistor-emitter.

An electronic device includes devices such as a power source, a power amplifier, and a speaker. The electronic device may supply an adaptable output voltage to the power amplifier based on a detected operating state of the speaker. Specifically, by designing a connecting circuit between the power source and the power amplifier, when the power amplifier operates on different circuits, the power source can provide different output voltages for the power amplifier, and then provide an adaptable driving power for the speaker.