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提出一种用于提取神经电信号的新型单片集成CMOS前置放大器.在放大器输入端引入的交流耦合电容可以消除存在于电极电解液之间的电极极化电压,栅源电压为负值的二极管连接的nMOS晶体管能够作为大电阻,并且占用很小芯片面积,可以通过此大电阻为前置放大器提供直流偏置,同时不影响输入阻抗值.通过对输入级进行理论噪声分析,确定了放大器中的各个器件参数.仿真结果表明,由于采用电容负反馈结构,此放大器的交流增益为38.8dB,无直流增益,在0.1Hz～1kHz频率范围内,总输入等效噪声为277nVrms.
A novel monolithic integrated CMOS preamplifier for extracting neural signals is proposed.The AC coupling capacitor introduced at the input of the amplifier can eliminate the electrode polarization voltage existing between the electrode electrolytes and the gate voltage is negative Diode-connected nMOS transistor can be used as a large resistor and occupy a small chip area, which can be used to provide a pre-amplifier DC bias, without affecting the input impedance value.Analysis of the input stage theoretical noise, to determine the amplifier The simulation results show that the amplifier has an AC gain of 38.8dB and no DC gain due to the capacitor negative feedback structure. The total input equivalent noise is 277nVrms in the frequency range of 0.1Hz to 1kHz.