A 36.8-μ W 66 nV/ √ Hz 85.7 dB-System-SNDR Reconfigurable Single-Channel ExG Acquisition System for Bio-Sensor Modules

This paper presents a fully integrated reconfigurable single-channel IC with high energy efficiency for bio-signal acquisition in Internet-of-Medical Things (IoMT) systems. The overall signal chain consists of a capacitively-coupled instrumentation amplifier (CCIA) and a 16-bit delta-sigma ( Delta Sigma ) ADC. The ADC is directly driven by the CCIA without a traditional driver stage. The folded path of the first stage in CCIA is sliced for reconfigurable noise levels. In addition, a single-stage floating inverter amplifier (FIA) assisted by the correlated-level-shifting (CLS) technique is employed in the switched-capacitor (SC) Delta Sigma modulator for fully dynamic operation with sufficient DC gain. Fabricated in 180-nm CMOS, the CCIA achieves an input-referred noise level ranging from 35.8 to 67 nV/ root Hz with a best noise-efficiency factor (NEF) of 5.54. It corresponds to an integrated noise ranging from 0.63 to 1.16 mu V-rms (0.5-100 Hz) and 1.93 to 3.51 mu V-rms (0.1-3 kHz), respectively. The ADC achieves a peak SNDR of 92.6 dB for a 2.3- V-pp differential input and can support 16 x power/BW reconfigurability with ENOB > 15 bit. The complete system occupies an active area of 0.56 mm (2) and achieves 85.7-dB system SNDR over a 500 Hz BW with an OSR of 128. It consumes 36.8 mu W from a 1.8-V supply, corresponding to an SNDR-based Schreier FoM of 157 dB. Biological measurement is demonstrated successfully, and the results verify that the proposed IC is applicable to high-quality ExG signal acquisition.