The signal to be amplified is fed sequentially to the first amplifier (2) and then to the second amplifier (6) with a lower maximum output level. The output signals of the two amplifiers (2, 6) are supplied to a directional signal coupler for formulating an output signal. There is at least one signal level reduction device, providing an equalising of the interference signal level in both of the amplifier output signals. A phase rotator (3) effects a phase shift of both output signals. Preferably the level reduction device has an attenuator arrangement.
