A 0.5V 1KS/s 2.5nW 8.52-ENOB 6.8fJ/conversion-step SAR ADC for biomedical applications

Abstract

A low-FOM SAR ADC using the leakage reduction bootstrapped switch (LRBS) to achieve a satisfactory ENOB and using a low-power approach with a low voltage, low sampling rate, and low-DAC-capacitance structure is presented for biomedical applications. LRBS is proposed to alleviate the leakage caused by the low-power approach to increase SNDR and ENOB. From the measurement results, the 0.18μm CMOS prototype chip with the total DAC capacitance of 2.765pF consumes 2.5nW and achieves a SNDR of 53.05dB under a 0.5V supply voltage at 1KS/s with a Nyquist input. The resulting FOM is 6.8fJ/conversion-step.