An 8-b 50-MHz 225-mW submicron CMOS ADC using saturation eliminated comparators

The fastest, low-power 8-b CMOS subranging A/D converter with a 50-MHz conversion rate and 225-mW power consumption is realized using 0.8-μm CMOS technology. The comparator used in the converter has a saturation elimination circuit, which eliminates the comparison delay caused by saturation. This circuit is useful for improving conversion speed or reducing converter power consumption. It is also effective in achieving low-power medium-speed converters. An 8-b 20-MHz 65-mW A/D converter can also be achieved with the same circuitry by decreasing the bias current. Therefore, this new converter makes it possible to realize mixed digital-analog ASICs for HDTV and for ED/IDTV applications