Patent ID: 8278840
Filing Date: 2012-10-02
Classification: H05B,Y02B

Abstract:
1. A circuit arrangement comprising a first light emitting diode and a second light emitting diode emitting light of different colors arranged adjacent to each other for additive color mixing; a first and a second controllable current source coupled to the first light emitting diode and a second light emitting diode, respectively, such that load currents of the first and second light emitting diodes depend on respective control signals received by the first and second current sources; a first and a second sigma-delta modulator coupled to the first light emitting diode and the second light emitting diode, respectively, and providing bit-streams as control signals to the first and second current sources, whereby a mean value of each bit-stream corresponds to a value of an input signal of the respective first or second sigma-delta modulator; and a further modulator receiving as an input signal a brightness signal whose value represents a desired brightness and generating a further bit-stream whose mean value represents the desired brightness.