A circuit arrangement for an optical monitoring system comprises a driver circuit configured to generate at least one driving signal for driving a light source and a detector terminal for receiving a detector current. The circuit arrangement further comprises a current source configured and arranged to generate at the detector terminal a reduction current. The reduction current has an amplitude which is given by a base value whenever none of the least one driving signal assumes a value suitable for activating the light source and by a sum of the base value and a reduction value otherwise. The circuit arrangement also comprises a processing unit configured to generate an output signal depending on a combination of the detector current and the reduction current.
