One-Wire Frequency-Division Multiplexing Multi-Channel Biopotential Active Electrode with Harmonic Cancellation.

Biopotential signal acquisition for ECG, EEG, and other ExG monitoring applications is tending toward higher electrode count to provide increased resolution and accuracy. In turn, increasingly large wire bundles limit both scalability and ambulatory use. Frequency-division multiplexing (FDM) architectures have been employed to decrease wire count, where channel count is limited by modulation harmonics. In this work, we present an FDM-based active electrode architecture that uses harmonic cancellation to extend the available modulation frequency bandwidth by 3X compared to recent state-of-the art FDM-based biopotential readout systems, while maintaining similarly low power operation. Measured results from a 0.18 mu m CMOS prototype IC demonstrate single- and multi-channel operation, with each active electrode circuit consuming only 12 mu W and 0.3mm2 per channel. In addition, fully digital demodulation enables one-wire operation between multiple active electrodes and a back-end readout system. This approach addresses a fundamental challenge for future scalability applied to manyelectrode bioelectrical measurement systems.