US Patent 7394994 Optical receiver circuit

An optical receiver circuit comprising an optical converter circuit (38), comprising a photodiode and converting optical power into electrical power, a sensor circuit for deriving a control voltage VCONTR as a characteristic value of the electrical power output by the optical converter circuit (38); and an attenuator circuit (44) having a variable attenuation, the attenuation being controlled by the characteristic value of the electrical power output by the sensor circuit so as to obtain a constant output signal level of the optical receiver circuit. An output circuit is also provided and comprises a matching network (46), an amplifier stage (48) and an output transformer (50).