A 0.053 mm2 10-bit 10-ks/s 40-nW SAR ADC with pseudo single ended switching procedure for bio-related applications

Abstract

This paper presents a power and area efficient pseudo single ended switching ADC for portable biomedical signal monitoring applications. The switching method features an 8-bit binary-weighted DAC array with a novel layout method called limited bottom-plate routing (LBPR) maintaining both feasibility and symmetry, a dynamic biased comparator and dynamic control logic. As a result, the proposed ADC saves 96.7% power consumption and 87.5% area occupation compared with conventional SAR ADC. Also, a novel DAC array layout method is promoted maintaining both feasibility and symmetry. A prototyped chip including a proposed ADC is fabricated in a 0.13 μm CMOS process. On condition of 0.6 V supply voltage and 10 kS/s sampling rate, the measured signal-to-noise-distortion (SNDR) and spurious free dynamic range (SFDR) are 57.8 dB and 64.3 dB, respectively. Besides, the ADC consumes only 40 nW power and 0.053 mm2 area achieving a figure-of-merit (FoM) of 6.26 fJ/conversion-step. Low power and low area occupation make it a good candidate for biomedical signal monitoring applications.