Design Optimization of a Low-Power and Low-Complexity Digital Driven-Right-Leg Circuit for Active-Electrode Measurement Systems

This article presents a methodology for optimizing the design of a digital driven-right-leg (DRL) circuit for use in improving the common-mode rejection ratio (CMRR) of multichannel active-electrode (AE) biopotential measurement systems operating with dry electrodes. Taking into consideration important design aspects including stability and performance, the proposed methodology aims to maximize the system’s CMRR while minimizing the DRL circuit’s complexity and power consumption. Our design methodology is validated through an ECG measurement system implemented with discrete components. Measured results show that, even with low-resolution data converters, the digital DRL circuit can help boost the overall CMRR by 77.6 dB. With only 6 bits of resolutions for its data converters operating from a full-scale range of 3.3 V, the proposed DRL circuit enables an AE pair, with a poor intrinsic CMRR of 38.26 dB and without the help of any notch filtering, to acquire ECG from dry electrodes with unnoticeable powerline interference.