Pass the weak magnetic field through a high-gain amplifier that amplifies it 1000 times

OP37 is a broadband ultra-low noise OP amplifier . Good noise characteristics can be obtained with small signal source resistance . We set the amplification factor of the amplifier to 1000 times. In order to reduce power supply interference, a CR decoupling circuit port is added to the power line. In the low frequency band , if the resistance of the feedback resistor is not reduced, it will be restricted by noise . Here we select Ri=IOOC>, R2=iOkQ. Since the operating level of the OP amplifier is very high, there is no need to consider the influence of noise. . The low frequency characteristics are composed of ca, ugly 5 and mouth. , determined by I, so the parameters of these components can be selected according to the signal frequency.