Patent ID: 8125162

Claim:
A light emitting diode (LED) driver circuit for controlling current through a first LED and a second LED, the LED driver circuit comprising: a current generator for generating a first current for the first LED and a second current for the second LED; a first sub-circuit connected to the first LED, the first sub-circuit comprising: a first transistor connected to the current generator for receiving the first current from the current generator; a first operational amplifier (OPAMP) connected between a first switch and the first transistor, wherein a first input terminal of the first OPAMP is connected to the first switch, and an output terminal of the first OPAMP is connected to a first terminal of the first transistor, a second switch and a third switch; a second transistor connected to the first LED, wherein a first terminal of the second transistor is connected to the second switch; and a second sub-circuit connected to the second LED, the second sub-circuit comprising: a third transistor connected to the current generator for receiving the second current from the current generator; a second OPAMP connected between a fourth switch and the third transistor, wherein a first input terminal of the second OPAMP is connected to the fourth switch, and an output terminal of the second OPAMP is connected to a first terminal of the third transistor, the third switch and the second switch; a fourth transistor connected to the second LED, wherein a first terminal of the fourth transistor is connected to the third switch; wherein the first sub-circuit and the second sub-circuit are connected to each other such that: the first switch switches the first input terminal of the first OPAMP and the fourth switch switches the first input terminal of the second OPAMP between the first LED and the second LED with a predefined frequency; and the second switch switches the first terminal of the second transistor and the third switch switches the first terminal of the fourth transistor between the output terminals of the first OPAMP and the second OPAMP with the predefined frequency.