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| An EEG Acquisition System with Dynamic DC Suppression |
| GAO Dong-rui, LIU Tie-jun, CAI Jia, SHI Xun, DING Chao, XU Peng, YAO De-zhong |
| Key Laboratory for Neurolnformation of Ministry of Education, School of Life Science and Technology, University of Electronics Science and Technology of China, Chengdu Sichuan 610054, China |
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Abstract A three op-amps instrumentation amplifier (I.A) is one of the most important segments in the electroencephalographic (EEG) acquisition system, which is used to suppress the interference of the common mode noise. However, electrode and op-amps offset voltages could saturate the I.A, so the ability of noise suppression for the I.A might be limited. To compensate for the electrode and op-amps offset voltages and improve the property of the I.A, the optical-isolated technology was used in the present study.
This paper described the theory of DC suppression and employed the simulation software(i.e. Multisim10.0.) to demonstrate the constant<urrent source of the optical-isolated device comprised of general-purpose optocouplers. Using this technology we designed and tested an EEG acquisition system. During the test, a constant current was generated by the optocoupler (the MOTOROLA 4N35) when DC offset voltages from 0 to 15 mV were imposed on the input signal in the EEG acquisition system and the value of load resistance in the optical-isolated device was from 3 k to 15 kom.
We also found that the IA with the gain of 857 could effectively reject a DC input range of ±15mV. And An EEG signal is obtained by the EEG acquisition system, and a CMRR of 104.5 dB was achieved without trimmings.
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Received: 15 January 2022
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Corresponding Authors:
GAO Dong-rui. E-mail：gdr1987@126.cam
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