22.2 A Rugged Wearable Modular ExG Platform Employing a Distributed Scalable Multi-Channel FM-ADC Achieving 101dB Input Dynamic Range and Motion-Artifact Resilience

Abstract

Wearable ExG biopotential acquisition systems can potentially capture a wealth of clinically useful diagnostic information during activities of daily life. In practice, however, motions from common activities introduce large artifacts that can easily saturate traditional analog front-ends (AFEs) designed to sense biopotentials on the micro- to milli-volt scale. In addition, the wires that connect each electrode to an array of high-impedance AFEs can easily pick up interference and large, potentially saturating artifacts. For these reasons, many-channel monolithic biopotential sensing systems are often fragile and difficult to use in ambulatory environments. While active electrodes can be used to combat interference picked up by high-impedance wires, they require power-hungry drivers to deliver high-fidelity signals across relevant anatomy to an array of ADCs. Placing an ADC on each active electrode followed by a digital bus driver can eliminate analog driver power, resulting in a per-channel power consumption of 104μW in [1]. However, the 12b SAR ADC in [1] could not tolerate significant motion artifacts, and further increasing the ADC resolution to accommodate a larger dynamic range (DR) would require a quadratic increase in per-channel ADC power consumption.