A 16-Channel Neural Signal Recording IC Achieving a 4-to-90-Hz Tunable High-Pass Cutoff Frequency based on a PVT-Insensitive Pseudo-Resistance Technique

State-of-the-art capacitively coupled neural signal recording front-ends require a sufficiently low and tunable high-pass cutoff frequency (f
HP
), which is typically formed with a G-to-TΩ pseudo-resistor (PR) rendering the f
HP
vulnerable to process variations. This study presents a 16-channel neural recording front-end that features superior uniformity and tunability in the f
HP
S of different channels. A self-biased current source (SBCS) is utilized to generate a picoampere (pA) bias current, which is further tuned through a specifically designed current-mirror digital-to-analog converter (DAC). The IC is fabricated in a 180-nm CMOS technology and occupies an area of 3.75 mm
²
. The resistance of the PR (R
PR
) features an 86% reduction in the relative standard deviation compared with the conventional design. The measured tuning range of the f
HP
across different channels shows remarkably consistency which covers from 4 Hz to 90 Hz.