A 64.8~μ W > 2.2 G Ω DC–AC Configurable CMOS Front-End IC for Wearable ECG Monitoring

This paper presents a low-power and high input impedance dc-ac configurable CMOS front-end integrated circuit (IC) for wearable ECG monitoring. This IC mainly includes three parts, namely: 1) high input impedance dc-coupled instrumentation amplifier; 2) AC-coupled programmable gain amplifier; and 3) low-power single operational amplifier continuous-time ΣA modulator. In addition, on-chip power management and clock generator were implemented to minimize the device size of the ECG monitoring system. This IC can be configured to dc-coupled topology to achieve ultra-high input impedance for dry electrode, and ac-coupled topology to achieve better electrode dc offset suppression for wet electrode. A baseline wander tracking technique is proposed to eliminate baseline disturbance, and a right-leg-driven circuit is realized to enhance the common-mode rejection ratio and minimize the 50/60 Hz power line interference. Fabricated in 0.18-μm CMOS process, this front-end IC occupies 0.24 mm2active area and consumes 64.8 μW from a 1.8-V supply. It achieves peak SNR 54.7 dB, spurious free dynamic range 58.2 dB, input impedance higher than 2.2 GQ, and dc suppression as large as ±300 mV.