A 0.01-mm² Mostly Digital Capacitor-Less AFE for Distributed Autonomous Neural Sensor Nodes

Abstract

This letter presents a miniaturized neural recording analog front-end (AFE) suitable for distributed sub-mm neural recording implants. Including reference generators, this AFE occupies an area of only 0.01 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , thanks to a mostly digital architecture with more than half of area being scalable digital logic. Implemented in 65-nm CMOS, the AFE is measured to consume 3.2 μW of power from 0.6-V supply, and achieves an input-referred noise of 2.2 μV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> over 500 Hz of bandwidth. The AFE is validated by integrating it into a neural sensing SoC with wireless power and data telemetry. In vitro experiments demonstrate reliable recording of the AFE in a fully wireless environment.