Sigma Delta Current Source and LED Driver
First Claim
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; and
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.
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Accused Products
Abstract
A circuit arrangement includes 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 second controllable current sources are connected to the first and second light emitting diode, respectively, such that the load currents of the light emitting diodes depend on respective control signals received by the current sources. First and second sigma-delta modulators are connected to the first and second light emitting diodes, respectively, and provide bit-streams as control signals to the current sources. The mean value of each bit-stream corresponds to the value of an input signal of the respective sigma-delta modulator.
28 Citations
20 Claims
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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; and 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for driving a multi-color LED arrangement comprising at least a first and a second light emitting diode arranged adjacent to each other for additive color mixing, the method comprising:
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providing a color signal for each light emitting diode, the color signals defining an effective color of the LED arrangement; generating a bit-stream for each color signals such that a mean value of the bit-stream represents the respective color signal; providing a load current to each light emitting diode depending on the respective bit- stream, such that a mean load current of each light emitting diode corresponds to the respective color signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A circuit comprising:
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a first light emitting diode of a first color; a second light emitting diode of a second color arranged adjacent the first light emitting diode, the first color different than the second color such that a combination of the first and second colors is for additive color mixing; a first controllable current source with an output coupled to the first light emitting diode; a second controllable current source with an output coupled to the second light emitting diode; a first sigma-delta modulator with an output coupled to an input of the first controllable current source; and a second sigma-delta modulator with an output coupled to an input of the first controllable current source. - View Dependent Claims (18, 19, 20)
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Specification