US Patent 8716947 LED current source digital to analog convertor

Various embodiments relate to a method of producing a high precision current using N current mirrors, a feedback control amplifier, and a reference current regulator to drive a light emitting diode, including: selecting one of the N current mirrors as a first current mirror; driving the first current mirror using a reference current produced by the reference current regulator; measuring a first sense voltage at the first current mirror; measuring a second sense voltage at a second current mirror that is one of the remaining N−1 current mirrors; integrating a difference of the first sense voltage and the second sense voltage to produce a feedback signal; and driving the remaining N−1 current mirrors using the feedback signal.