A read-in IC for infrared scene projectors with voltage drop compensation for improved uniformity of emitter current

Abstract

This paper proposes a read-in integrated circuit (RIIC) for infrared scene projectors, which compensates for the voltage drops in ground lines in order to improve the uniformity of the emitter current. A current output digital-to-analog converter is utilized to convert digital scene data into scene data currents. The unit cells in the array receive the scene data current and convert it into data voltage, which simultaneously self-adjusts to account for the voltage drop in the ground line in order to generate the desired emitter current independently of variations in the ground voltage. A 32 x 32 RIIC unit cell array was designed and fabricated using a 0.18-mu m CMOS process. The experimental results demonstrate that the proposed RIIC can output a maximum emitter current of 150 mu A and compensate for a voltage drop in the ground line of up to 500 mV under a 3.3-V supply. The uniformity of the emitter current is significantly improved compared to that of a conventional RIIC.