Marine Electric Field Signal Amplification Circuit with Ultra Low Noise and High Input Impedance

In this paper, for the high impedance marine electric field sensor (MEFS), a marine electric field signal amplification circuit (MEFSAC) with ultra low noise and high input impedance is designed, and the noise analysis of the circuit is carried out. In order to achieve the ultra low noise performance of the circuit, the chopper modulation technology is introuduced to reduce the flicker noise generated by the circuit. The AC amplifier stage with instrumentation amplifier structure is implemented to achieve the coupling of the circuit with the sensor to reduce coupling noise, and the low-pass filter stage with a cut-off frequency of 100Hz is designed to filter out the high-frequency signal generated by the circuit. The noise model of the MEFSAC is established, and the noise of the MEFSAC is analyzed theoretically and the simulation is verified. The gain of the MEFSAC is 60dB, and the background noise of the MEFSAC is 1.87nV/rt(Hz). Through the analysis of circuit noise model, it provides a better method for seeking circuit noise suppression.