A 0.62 μW/sensor 82 fps Time-to-Digital Impedance Measurement IC with Unified Excitation/Readout Front-end for Large-Scale Piezo-Resistive Sensor Array

Abstract: This paper presents a fast impedance measurement IC for large-scale piezo-resistive sensor array. It features a unified differential time-to-digital demodulation architecture that readout impedance directly through the excitation circuit. The proposed pre-saturation adaptive bias technique further improves power efficiency. The chip scans 253 sensors in 12.2 ms (82 fps) at 125 kHz, consuming 158 {\mu}W (7.5 nJ/sensor). With loads from 20 {\Omega} to 500 k{\Omega}, it achieves 0.5% error and up to 71.1 dB SNR.