An 8-bit 450-MS/s single-bit/cycle SAR ADC in 65-nm CMOS

Abstract

A low-energy 8-bit 450-MS/s single-bit/cycle SAR ADC is presented. The design combines top-plate sampling, small unit capacitances (0.75 fF), symmetric DAC switching, and judicious delay optimization around a single high-speed comparator to achieve an ENOB of 7.6 at Nyquist, translating into an FOM of 76 fJ/conversion-step. The converter occupies an active area of 0.035 mm2 in 65-nm CMOS.