Abstract: A power amplifier for amplifying an electric input signal in an operational frequency range and providing an output signal, comprising switching means (22), filter means (14, 15) for generating a power output signal by low pass filtering a block wave signal, input means for receiving the electric signal and feeding it to a first input of the switching means, the power amplifier further comprising a feedback circuit (24) connecting the output signal to the first input of the switching means. The power amplifier comprises a servo amplifier (32) connected to receive an error signal appearing at the first input of the switching means and to feed a correction output signal to a second input of the switching means (22) for neutralizing an impact of the error signal on the output signal. The invention relates to a method of amplifying an electric input signal in an operational frequency range.