A 0.2-V 1.2 nW 1-KS/s SAR ADC with a novel comparator structure for biomedical applications

Abstract

In this paper, a modified successive-approximation-register analog-to-digital converter (SAR ADC) with a novel low power dynamic comparator at 0.2 V supply voltage is presented. The power consumption of SAR ADC has been reduced by 70% with design of proposed low-power comparator and using power reduction techniques such as power gating and reducing the supply voltage. Also, by custom design for unit capacitor in the SAR ADC, the area has been reduced by 46% compared to the conventional structure. The proposed ADC with a sampling frequency of 1 kS/s and power consumption of only 1.21 nW for biomedical applications has been designed and simulated in a TSMC 65 nm CMOS technology and occupies an area of 0.013 mm2. The proposed biomedical ADC is verified using analog electroencephalogram (EEG) and electrocardiogram (ECG) inputs which demonstrate it is proper to quantize these biosignals. The figure-of-merit (FOM) of the proposed converter is 3.2 fJ/conversion-step.