A Resolution-Reconfigurable 5-to-10b 0.4-to-1V Power Scalable SAR ADC

A resolution-reconfigurable 5-to-10b SAR ADC for micro-power sensor nodes is implemented in a low-leakage 65nm CMOS process, operating from 2MS/s at 1V to 5kS/s at 0.4V, with power that is linear with sample rate. The DAC power and ADC input capacitance scale exponentially with resolution, and voltage scaling further reduces the energy-per-conversion. Leakage power-gating is applied at low sample rates to reduce the minimum energy point of the ADC. The figure-of-merit is 22.4fJ/conversion-step in 10b mode at 0.55V.