A 24.8-μW Biopotential Amplifier Tolerant to 15-VPP Common-Mode Interference for Two-Electrode ECG Recording in 180-nm CMOS

This article presents a biopotential amplifier that has a large tolerance to common-mode interference (CMI) for a reliable two-electrode electrocardiogram (ECG) recording. To withstand large CMI without affecting the ECG signal, a common-mode charge pump (CMCP) that absorbs displacement current from the CMI and keeps the common-mode input within the desired range is proposed. This article also analyzes the effects of CMCP under non-ideal conditions and provides design guidelines for improved signal quality. A prototype chip fabricated in 180-nm CMOS achieves CMI tolerance of 15 VPP at 60 Hz while consuming 24.8 μW from a 1.2-V supply.