An 18.6-$\mu $W/Ch TDM-Based 8-Channel Noncontact ECG Recording IC With Common-Mode Interference Suppression

This paper presents an 8-channel electrocardiogram (ECG) monitoring integrated circuit (IC) controlled by time-division multiplexing (TDM). The proposed TDM compensates the electrode DC offsets by forming an individual discrete-time feedback loop per channel while sharing an analog frontend. This enables a chopping-free open-loop amplification, achieving a high input impedance suitable for a noncontact ECG monitoring. In addition, a common-mode interference (CMI) cancellation scheme is also introduced in the proposed TDM schedule for the realization of a pseudo-driven-right leg (DRL) in a multichannel environment. The designed system is implemented in 180 nm CMOS. The chip dissipates 18.6 μW/channel including the power consumption by ADC. It shows the total-CMRR of 100 dB against CMI voltage swing up to 20 V_PP. The chip is verified in noncontact 8-channel ECG using conventional passive electrodes.