脑电信号预处理电路的设计

Design of electroencephalogram signal pre-processing

①原始的脑电信号十分微弱,一般都在10～50μV,必须进行放大。文内主要介绍了前置电路和主放大电路的设计。②在对脑电放大的同时,电极的极化电压、高频干扰电压、以及产生干扰最严重的50Hz工频干扰电压也随之放大,故必须使用滤波器对这些干扰电压加以滤除,必要时,使用光电耦合进行隔离。文内还介绍了脑电采集系统中使用的滤波电路:包括低通滤波器、高通滤波器、50Hz工频陷波器的设计与实现。经过处理之后,可以得到高质量的脑电信号,然后进入AD转换器进行转换,以便进一步处理。

Original electroencephalogram （EEG） must be magnified because its voltage is very low, usually between 10-50μV. In this paper, preamplifier and main amplifier is introduced. While magnifying EEG, the polarizing voltage of electrodes, voltage of high frequency interference, voltage of 50 Hz industrial frequency that disturbs EEG worst, are all magnified at the same time. We must use filters to filter these interferences. Photo-electric coupling is used when necessary. Additionally, the filter circuits used in EEG collecting system are introduced, including a low-pass filter, a high-pass filter and a 50 Hz-trap filter. After pre-processing, we can acquire high-quality EEG signals, which are sent to AD converter, easy being processed in following steps.