A Duty-Cycled Continuous-Time Delta-Sigma Modulator for ExG Biopotential Acquisition

Abstract

This paper introduces a continuous-time (CT) delta-sigma analog-to-digital converter (ADC) integrated with a capacitively-coupled chopper instrumentation amplifier (CCIA) for ExG biopotential recording. The design features a duty-cycled operation that enhances power efficiency by minimizing unnecessary power dissipation during low-frequency signal acquisition. The system is optimized to meet key requirements such as low noise, low power, high input impedance, and sufficient input range for various biopotential signals. Fabricated in a standard 0.18 μm CMOS process, the ADC achieves FoMSNDR of 170.1 dB for a 10 kHz bandwidth, consuming 4.5 μW at 0.6 V. The active area is 0.138 mm².