DYNAMICALLY CONTROLLABLE DRIVE CIRCUIT FOR PARALLEL ARRAY OF LIGHT EMITTING DIODES
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United States of America Patent
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app pub date -
Jan 8, 2013
filing date -
Mar 9, 2010
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Abandoned
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Abstract
The present invention relates to a parallel light emitting diode (“LED”) drive circuit and provides a drive circuit configured to drive a parallel array of LEDs. The drive circuit comprises: a switching control signal generator, a plurality of switches, a plurality of sampling resistors, and a plurality of chopper amplifiers. Each switch is coupled to a respective LED in the LED array. Each chopper operational amplifier configured to receive a reference voltage and a switching control signal generated by the switching control signal generator and generate an input offset voltage. Each chopper operational amplifier includes a differential amplifier including an input transistor pair and a current mirror transistor pair, of which the electrical positions can be reserved when the switching control signal is switched between a first state and a second state, wherein the offset voltage, which causes the lightness mismatching in a parallel LED circuit, can be cancelled.
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