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Sigma delta current source and LED driver

  • US 8,278,840 B2
  • Filed: 03/08/2010
  • Issued: 10/02/2012
  • Est. Priority Date: 03/12/2009
  • Status: Active Grant
First Claim
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1. A circuit arrangement comprisinga 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.

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