The design of a reconfigurable successive approximation analog to digital converter for biomedical applications

In a biomedical signal processing system, ADC is an important circuit that successively converts analog biomedical signals into digital data for next analysis and processing. However, the ADC operates continuously. The power consumption is a very important factor in ADC circuit design. This brief present a 10 bits and 8 bits reconfigurable SAR ADC with a sampling rate of 20KS/s for implantable devices. It adopt Single-ended split-array capacitive DAC to reduce Power consumption and area. The digital parts of SAR ADC operate at 0.5V. The analog parts operate at 1V and 0.6V in 10bits mode and 8bits mode, respectively. The power consumptions are 1.354μW and 152.28nW. DNL are -9m~0.22LSB and -0.02~0.21LSB. INL are -0.2~0.58LSB and -0.25~0.25LSB. ENOB are 9.1 and 7.7, respectively. The ADC achieves the FOM of 123.37fJ/conversion-step and 36.55fJ/conversion-step, respectively.