A Compact Chopper Stabilized Δ-ΔΣ Neural Readout IC With Input Impedance Boosting

This paper presents a scalable neural recording analog front-end architecture enabling simultaneous acquisition of action potentials, local field potentials, electrode DC offsets and stimulation artifacts without saturation. By combining a DC-coupled
$\Delta $
-
$\Delta \Sigma $
architecture with new bootstrapping and chopping schemes, the proposed readout IC achieves an area of 0.0077 mm
²
per channel, an input-referred noise of 5.53 ± 0.36
$\mu \text{V}_{\mathrm{ rms}}$
in the action potential band and 2.88 ± 0.18
$\mu \text{V}_{\mathrm{ rms}}$
in the local field potential band, a dynamic range of 77 dB, an electrode-DC-offset tolerance of ±70 mV and an input impedance of 663
$\text{M}\Omega $
. To validate this neural readout architecture, we fabricated a 16-channel proof of-concept IC and validated it in an
in vitro
setting, demonstrating the capability to record extracellular signals even when using small, high-impedance electrodes. Because of the small area achieved, this architecture can be used to implement ultra-high-density neural probes for large-scale electrophysiology.