Analysis : Electroencephalography Acquisition System: Analog Design

Abstract

Electroencephalography (EEG) is a sensitive and weak biosignal that varies from person to person. It is easily affected by noise and artifacts. Hence, maintaining the signal integrity to design an EEG acquisition system is crucial. This article proposes an analog design for acquiring EEG signals. The proposed design consists of eight blocks: (1) a radio-frequency interference filter and electro-static discharge protection, (2) a preamplifier and second-order high-pass filter with feedback topology and an unblocking mechanism, (3) a driven right leg circuit, (4) two-stage main and variable amplifiers, (5) an eight-order anti-aliasing filter, (6) a six-order 50-Hz notch filter (optional), (7) an opto-isolator circuit, and (8) an isolated power supply. The maximum gain of the design is approximately 94 dB, and its bandwidth ranges from approximately 0.18 to 120 Hz. The depth of the 50-Hz notch filter is −35 dB. Using this filter is optional because it causes EEG integrity problems in frequencies ranging from 40 to 60 Hz.

A Novel Battery-Supplied AFE EEG Circuit Capable of Muscle Movement Artifact Suppression

“…In EEG Generic Circuit Design, various subcomponents work together for accurate brainwave signal capturing and denoising. One of the most characteristic examples of them is the Filter subcomponents such as Notch, Anti-Aliasing, High Pass, and Low Pass Filters, which refine signals by eliminating interference and keeping only the frequency bands of interest from the input raw EEG signal [12]. Another example is the Circuit subcomponents, including Chopper Circuits and Electrostatic Discharge Protection (ESD), which minimize low-frequency noise and protect against electrostatic discharge damage.…”

“…Furthermore, the Analog Multiplexers select signals in multi-channel setups, while the Analog to Digital Converter digitizes the collected signals from the electrodes for further analysis [14]. Moreover, the Drive Right Leg Circuit reduces interference by introducing a feedback loop between the EEG device and the Human Body [12]. Last but not least, the Power Supply subcomponents, such as batteries and regulators, ensure a stable power supply for the device.…”

“…As it becomes apparent, each engineering decision has tradeoffs, that must be well understood for the design to meet its predefined requirements. Table 3 presents a structured overview of the various components involved in EEG circuits, along with their respective functions [12][13][14].…”

A Novel Battery-Supplied AFE EEG Circuit Capable of Muscle Movement Artifact Suppression

“…In EEG Generic Circuit Design, various subcomponents work together for accurate brainwave signal capturing and denoising. One of the most characteristic examples of them is the Filter subcomponents such as Notch, Anti-Aliasing, High Pass, and Low Pass Filters, which refine signals by eliminating interference and keeping only the frequency bands of interest from the input raw EEG signal [22]. Another example is the Circuit subcomponents, including Chopper Circuits and Electrostatic Discharge Protection (ESD), which minimize low-frequency noise and protect against electrostatic discharge damage.…”

Accurate neural network classification model for schizophrenia disease based on electroencephalogram data

“…The sampling rate was 500 Hz and the electrodes were placed following the International System 10-20 [32] with reference points Fpz/Afz/Fz/Cz/Pz/Qz. External interferences and artifacts existing in EEG signals due to electrical distribution network, breathing, eye-blinking, body movements, breathing or sweating were removed via ltering [33][34]. More speci cally, a notch lter at 50 Hz and a low pass lter with 40 Hz cut-off frequency were applied.…”