Designing a Low-Power LNA and Filter for Portable EEG Acquisition Applications

Abstract

A circuit with a low-power low-noise amplifier and a Gm-C ultra-low-power filter is proposed in this paper for portable electroencephalogram (EEG) acquisition applications. The proposed circuit contains a two-stage chopper-stabilized fully recycling folded cascode (TSRFC) amplifier and a second-order continuous-time Gm-C low pass filter (LPF) with ultra-low-power consumption. The noise and input offset are reduced using the chopper-stabilized technique. A two-stage amplifier that consists of composite transistors and a recycling structure is proposed for the amplifier. Compared to a typical folded cascode CMOS amplifier, the proposed design has higher DC gain and slew rate as well as lower input-referred noise. This circuit has an adjustable second-order Gm-C LPF with very low power consumption. The amplifier achieves a midband gain of 70 dB and a -3dB bandwidth in the range 0.1-212 Hz. Moreover, the amplifier is designed in 0.18-µm CMOS process and the chip area of the proposed circuit with pads is 450×450 μm 2 . The adjustable LPF has a 100 Hz cut-off frequency. The proposed circuit has an input-referred noise of 0.7 μVrms, (0.1~100Hz) and a power consumption of 380 nW at 1 V supply.INDEX TERMS Fully recycling folded cascode amplifier, chopper-stabilized technique, EEG, Gm-C filter, low-noise design.

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

“…A o,TC_OTA in ( 9) is g m r o times higher than A o,5TR_OTA in (3), while ω 3dB,TC_OTA in ( 10) is g m r o times lower than ω 3dB,5TR_OTA in (4). Note that ω GB,TC_OTA is same as ω GB,5TR_OTA in (5).…”

“…Operational transconductance amplifiers (OTAs), which convert an input voltage to an output current, play crucial roles in a wide range of electronic systems. 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].…”

0.36 μW/channel capacitively-coupled chopper instrumentation amplifier in EEG recording wearable devices for compressed sensing framework

“…14) The capacitively coupled chopper instrumentation amplifier (CCIA) architecture, which adds a chopping technique to the above configuration, has been extensively used as a lownoise amplifier (LNA) for EEG measurement. [15][16][17][18][19][20][21][22][23] In general, a tradeoff is present between the input referred noise (IRN) and the power consumption of an LNA. Research has been conducted to optimize this tradeoff, and the application of CS is considered one of the solutions.…”

BEATS: An Open-Source, High-Precision, Multi-Channel EEG Acquisition Tool System

“…Some researches focus on the study of electrodes [6], [7]. Others focus on analog-todigital conversion and transmission of EEG signals [8], [9], [10], [11], [12], [13], [14], [15]. Some of them also design a graphical user interface (GUI) for signal processing and analysis [16], [17].…”