Power efficient SAR ADC adaptive to input activity for ECG monitoring applications

The proposed 1.8-V 10-bit 1-kS/s successive approximation register (SAR) analog-to-digital converter (ADC) for electrocardiographic (ECG) monitoring applications has two operation modes suitable for the dichotomous activity of ECG signals: full and reduced switching modes. MSBs tracking and LSBs extrapolation run in full and reduced switching mode, respectively, for smooth mode changes adaptive to the input activity. A prototype chip was fabricated in 0.18-μm CMOS technology. The suitability of the proposed adaptive switching was proved by the measurements that the total power consumption was reduced by 15.3% compared to the full switching case.