Optical spectrometer , particularly a closed-loop optical spectrometer , comprising: at least one light source and/or at least one output for an external light source , wherein the at least one light source is current driven or the at least one output for an external light source is a current source, a spectroscopic sensor array , and an analog-to-digital converter for converting the signals of the spectroscopic sensor array , wherein the analog-to-digital converter is current driven, and a common controller for the at least one light source and/or the at least one external light source and the analog-to-digital converter that is located on a single semiconductor die or integrated in a single circuit , wherein the common controller is a common current controller comprising a first current controller and a second current controller for the at least one light source and/or the at least one output for an external light source and the analog-to-digital converter , wherein the first current controller and the second current controller share the same common voltage reference , wherein the first current controller comprises a first feedback controller , a first sensing resistor and a first current drive stage and the second current controller comprises a second feedback controller, a second sensing resistor and a second current drive stage characterized in that the common current controller further comprises a multiplexer for multiplexing between a first operating condition, in which the first feedback controller is connected to the first sensing resistor and the first current drive stage and in which the second feedback controller is connected to the second sensing resistor and the second current drive stage, and a second operating condition, in which the first feedback controller is connected to the second sensing resistor and the second current drive stage and in which the second feedback controller is connected to the first sensing resistor and the first current drive stage . at least one light source and/or at least one output for an external light source , wherein the at least one light source is current driven or the at least one output for an external light source is a current source, a spectroscopic sensor array , and an analog-to-digital converter for converting the signals of the spectroscopic sensor array , wherein the analog-to-digital converter is current driven, and a common controller for the at least one light source and/or the at least one external light source and the analog-to-digital converter that is located on a single semiconductor die or integrated in a single circuit , wherein the common controller is a common current controller comprising a first current controller and a second current controller for the at least one light source and/or the at least one output for an external light source and the analog-to-digital converter , wherein the first current controller and the second current controller share the same common voltage reference , wherein the first current controller comprises a first feedback controller , a first sensing resistor and a first current drive stage and the second current controller comprises a second feedback controller, a second sensing resistor and a second current drive stage characterized in that the common current controller further comprises a multiplexer for multiplexing between a first operating condition, in which the first feedback controller is connected to the first sensing resistor and the first current drive stage and in which the second feedback controller is connected to the second sensing resistor and the second current drive stage, and a second operating condition, in which the first feedback controller is connected to the second sensing resistor and the second current drive stage and in which the second feedback controller is connected to the first sensing resistor and the first current drive stage . <EOS>