A Low-Noise 0.001Hz-lkHz Sample-Level Duty-Cycling Neural Recording System-on-Chip.

Multiscale dynamics of neural and metabolic interactions implicated in disease states call for precision electrophysiology to resolve a variety of biopotential signals across the body that cover a wide range of frequencies, from the mHz-range electrogastrogram (EGG) to the kHz-range electroneurogram (ENG). Currently available integrated systems for unobtrusive and minimally invasive electrophysiology suffer from tradeoffs between bandwidth coverage, noise floor, power consumption, and input impedance, which limits their detection range and accuracy. Here we present a 16-channel wide-band ultra-low-noise neural recording system-on-chip fabricated in 65nm CMOS for chronic use in mobile healthcare settings that covers 0.001 Hz to 1 kHz bandwidth through sample-level duty-cycling. Each channel consists of a delta-sigma analog-to-digital converter (ADC) achieving $\mathbf{1.0}\ \mu \mathbf{V}_{rms}$ input-referred noise over 1 Hz - 1 kHz bandwidth with a Noise Efficiency Factor (NEF) of 2.93 in continuous operation mode, while power duty-cycling of the biasing and clocks maintains consistent low input-referred noise levels down to 0.001 Hz sampling rates at $\mathbf{435}\ \mathbf{M}\Omega$ input impedance. In vivo recordings from the chip interfacing to electrodes mounted on the forehead resolving slow-wave electroencephalogram (EEG) biopotentials demonstrate proof-of-concept functionality.