Design of a 12-b asynchronous SAR CMOS ADC

A low power asynchronous SAR 12b ADC for biomedical applications was designed in a 0.35μm CMOS technology. The split capacitor array DAC with an asynchronous SAR was employed for low power consumption and small die area. Measurement results show that the proposed ADC achieved the SNDR of 68.32 dli, the SFDR of79dB, and the ENOB of11.05 bits. The measured INL and DNL were 1.9/-1.3 LSBs and 1.5/-0.9 LSBs, respectively. The power consumption including all the digital circuits and FOM were measured to be 6.8μW and 49 fJ/Step, respectively at the sampling frequency of 99 KHz.