A 12-bit 100kS/s SAR ADC for Biomedical Applications

This paper describes a 12-bit 100kS/s successive approximation register analog-todigital converter (SAR ADC) for biomedical system. Both top-plate sampling technique and VCM-based switching technique are applied to the capacitor digital-to-analog converter (CDAC) to implement a 12-bit SAR ADC with 10-b capacitor array DAC. To enhance the linearity of proposed ADC, thermometer decoder is used in capacitor array DAC. Switching-energy minimization technique, asynchronous control with a low-power delay circuit and true single phase clocking (TSPC) D_FF are also adopted to reduce power consumption. Simulation results show that the proposed ADC achieves the SNDR of 70.97dB, the SDFR of 80.23dB and the ENOB of 11.49b with the CMOS 0.18m technology. Total power consumption is 11.16W under the supply voltage of 1.8V at the sampling frequency of 100 kHz. And the figure of merit (FoM) is 38.79fJ/conversionsteps.