生物电信号的特点是信号源内阻高,信号小,频带宽,低频端延伸至直流,例如脑电、胃电信号幅度约几十微伏,而体表希氏束电位的H波幅仅3微状左右。放大这些弱信号,有必要设计一个噪声低,输入阻抗高,并有一定共模抑制能力的直流放大器。我们设计了一个低噪声放大电路,用国产元件装配了数台,经实际应用,测试其噪声性能都在2μV Bioelectric signal is characterized by high signal source resistance, small signal bandwidth, low frequency extended to DC, such as brain electricity, gastric electrical signal amplitude of about dozens of microvolts, and surface His bundle potential H amplitude of only 3 micro Or so. To amplify these weak signals, it is necessary to design a DC amplifier with low noise, high input impedance and some common-mode rejection. We designed a low-noise amplifier circuit, assembled with a few domestic components, the actual application, the test noise performance at 2μV