A Low Power 12-bit 1-kS/s SAR ADC for Biomedical Signal Processing

In this paper, a 12-bit 1-kS/s successive approximation register analog-to-digital converter (ADC) is presented for biomedical signal processing system. A multi-segmentation digital-to-analog converter architecture and a hybrid switching scheme are proposed to reduce the total unit capacitor count. A new ultra low-leakage switch is proposed for sample-andhold and capacitor control switch blocks in order to improve conversion accuracy and reduce leakage current. The proposed ADC is fabricated in 130-nm CMOS process with a core area of 0.16 mm(2). The measurement results show that the ADC achieves 10.47 ENOB and consumes 110-nW power at a sampling rate of 1 kS/s with 1.0-V supply voltage. A Walden figure of merit of 76 fJ/conversion-step is obtained.