A broad-band amplifier for the amplification of a photoelectric current triggered by a light signal, including a first transistor connected to receive the photoelectric current, a second transistor connected in series with the first one, a resistance connected between the base of the first transistor and the emitter of the second transistor, a third transistor and a fourth transistor which form a current mirror, the third transistor being connected in series with the second transistor, and a resistance located between the third transistor and ground.