An 8-bit two-step flash A/D converter for video applications

A novel configuration for two-step analog-to-digital (A/D) flash conversion is described. The coarse and fine conversions are performed with a four-bit multiplexed flash converter, so only 15 comparators are necessary for an eight-bit converter. The D/A conversion and the subtraction required for the circuit operation are performed using the charge redistribution technique. A test chip, integrated with a 3-μm CMOS technology (area=3 mm
²
), has demonstrated the effectiveness of the proposed configuration