An amplifier circuit (200) for compensating an output signal provided at an output (212) of a circuit (210) is disclosed. The amplifier circuit (200) comprises an output transmission line (230) connected between the output (212) of the circuit (210) and an output port (240) and an amplifier (220). The amplifier (220) comprises multiple sub-amplifiers (221, 222, 223, 224), inputs of the multiple sub-amplifiers (221, 222, 223, 224) are coupled to an input transmission line (250) for receiving an error signal; and outputs of the multiple sub-amplifiers (221, 222, 223, 224) are coupled at respective places along the output transmission line (230) to inject a compensation signal to the output port (240). The error signal is derived from a reference input signal and the output signal of the circuit (210), and is amplified in the amplifier (220) into the compensation signal.

An electronic device includes a driving amplifier, a power amplifier, a power detector, and a bias circuit. The driving amplifier outputs a radio frequency (RF) signal. The power amplifier is electrically connected to the driving amplifier. The power amplifier includes an input end. The power amplifier receives the RF signal through the input end. The power amplifier amplifies the RF signal. The power detector is electrically coupled to the input end and detects the input power of the RF signal. The power detector outputs a driving voltage according to the input power. The bias circuit is electrically connected to the power amplifier and the power detector. The bias circuit outputs a first driving current to the power amplifier according to the driving voltage. The power amplifier amplifies the power of the RF signal from the input power to a target power according to the first driving current.

Techniques for controlling the output of a power amplifier are disclosed. In one embodiment, the techniques may be realized as a system that includes a power amplifier and a controller coupled to the power amplifier to form a feedback loop. The power amplifier is enabled or disabled in response to a blanking signal. The controller includes an accumulator that stores an accumulated error of the feedback loop. The controller suspends operation of the accumulator when (1) a level of the input signal is below a first threshold for an amount of time that exceeds a second threshold, (2) the blanking signal indicates that the power amplifier is disabled, or (3) both. The controller resumes operation of the accumulator when (1) the level of the input signal is above the first threshold and (2) the blanking signal indicates that the power amplifier is enabled.