Abstract: A feedforward amplifier system comprises a main amplifier and an auxiliary amplifier. An input signal including one carrier signal used as a first pilot signal, is supplied to a main amplifier to produce an amplified output signal. A second pilot signal is injected into the amplified output signal. The amplified output signal from the main amplifier is supplied to an output of the amplifier system through a delay line. In each of a first loop associated to the main amplifier and a second loop including the auxiliary amplifier, two control signals with pilot signal components arc produced, discrete Fourier transforms of the pilot signal components of the two control signals are calculated, and the amplitude and phase of the input signal of the main or auxiliary amplifiers are adjusted to values making the two Fourier transforms substantially equal to each other. Alternatively, the first pilot signal is produced by a generator and is injected into the input signal.