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 180 nm 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.

Single-Stage CMOS Operational Transconductance Amplifiers (OTAs): A Design Tutorial

“…G m -C filters, based on OTAs, have been employed in sensor interface integrated circuits (ICs) [1][2][3], biopotential recording circuits [4][5][6], and wireless communication integrated circuits (ICs) [7][8][9] to attenuate interferers with a wide tuning range of cut-off frequencies. OTA-based integrators with an inherent high gain and low-pass frequency response have been used in delta-sigma analog-to-digital converters (ADCs) [10][11][12]. Moreover, OTAs themselves have served as feedforward amplifiers of closed-loop systems such as capacitively coupled instrumentation amplifiers (CCIAs) [13][14][15] and power ICs [16][17][18][19][20] thanks to their high gain performance.…”