A Wide Dynamic Range Sigma-Delta Modulator for EEG Acquisition Using Randomized DWA and Dynamic-Modulated Scaling-Down Techniques

Abstract

This paper proposes a wide dynamic range (DR) and high-resolution discrete-time (DT) 2-order 4-bit sigma-delta modulator with a novel dynamic-modulated scaling-down (DM-SD) technology for non-invasive electroencephalogram (EEG) acquisition. The DM-SD technology can expand the input dynamic range and suppress large input offsets at the same time. The modulator was designed with 180nm CMOS technology with an area of 0.49 mm2. We achieve a 118.1 dB SNDR when the input signal is 437.5 Hz and the signal bandwidth is 1500 Hz. Due to the proposed DM-SD technology, the DR is expanded to 126 dB. The power consumption of the whole modulator is 1.6 mW and a 177.8 dB Schreier figure-of-merit (FoMs) is realized.

Keywords

• ΣΔ modulator
• analog-to-digital (ADC)
• dynamic range (DR)
• electroencephalogram (EEG)
• dynamic-modulated scaling-down (DM-SD)
• low parasitics capacitance