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.