A sEMG signal acquisition circuit with high common mode rejection ratio,flexible amplification and good anti-noise performance is designed in view of the sEMG characterized by low frequency and weak signal vulnerable to interference. The amplified part of the signal uses a two-stage amplification scheme to avoid the problem that the noise is excessively enlarged to cause the EMG signal to be submerged. The band-pass filter section composed of two groups of 5-order Sallen-Key low-pass and high-pass filtering circuits makes the stop-band decrease rapidly,approximately to-100 dB/( °) ,so as to attenuate the noise and other physiological signal interference to a large extent. For the power frequency interference problem,this design sets the Q value adjustment potentiometer in the trap part,adjusting the potentiometer to obtain the best collection effect according to the actual situation. The test results show that this design with amplifier gain up to 60dB has a good inhibitory effect of 50 Hz interference,can effectively extract the useful sig-nal between 20 Hz～500 Hz,and has a good anti-noise performance.%针对表面肌电信号(sEMG)信号微弱、频率低、极易受到干扰的特点,设计了具有高共模抑制比、放大增益灵活可调、具有良好抗噪声性能的sEMG信号采集电路.信号的放大部分采用两级放大方案,以避免噪声被过分放大造成肌电信号被淹没的问题.带通滤波器部分由两组5阶Sallen-Key低通和高通滤波电路级联而成,阻带下降速度很快,近似达到-100 dB/(°),对噪声及其他生理电信号干扰的衰减能力极强.针对工频干扰问题,在陷波器部分设置Q值调节电位器,根据实测情况灵活调节电位器旋钮以便获取最佳采集效果.测试结果表明,所设计的电路放大增益可以达到60 dB,对50 Hz工频干扰有很好的抑制作用,可以有效提取20 Hz～500 Hz之间的有用信号,具有良好的抗噪声性能.
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