Low power 8-b CMOS current steering folding-interpolating A/D converter

This paper presents a CMOS A/D converter based on the folding and interpolating technique. A current steering folder composed of differential pairs allows low power operation and an interpolation is used for high speed with low supply voltage. In a folding circuit, only twenty-three MOSFETs are required to have eight reference voltages of an 8-b A/D converter. The interpolation is implemented with a current division technique to generate 32 folding signals. This approach requires much less area and power consumption than other conventional flash A/D converter. The simulation in a 0.35 mu m CMOS process achieves 8-b resolution at 250 Msample/s with power consumption 70 mW at 3.3 V power supply. The preliminary experiment indicates the current steering folder and coarse bits operate as expected.