A 3.9 mu W, 81.3dB SNDR, DC-coupled, Time-based Neural Recording IC with Degeneration R-DAC for Bidirectional Neural Interface in 180nm CMOS

Abstract

This paper presents a 5-bit VCO-based neural recording IC, which directly quantizes the input signal and achieves a large dynamic range (DR) to process the small-amplitude neural signal in the presence of the large-amplitude stimulation artifact (SA). A feedback-controlled source degeneration is applied to the input transconductor circuit (Oxon) by using a resistor DAC (R-DAC). It mitigates the circuit nonlinearity, resulting in a large signal-to-noise-and-distortion ratio (SNDR) and a high input impedance (Zai). The implemented neural recording IC achieves 81.3dB SNDR over 2001z signal bandwidth and 200mNpp maximum allowable input range while consuming 3.9p..'W per channel.