Research on Low Noise Chopping Amplifier Circuit Based on Feedback Regulation

Abstract

In order to overcome the limitation of 1/f noise on long-period magnetotelluric sensors, it is necessary to use low-noise chopping technology for signal conditioning. However, the static operating point drift of Junction Field-Effect Transistor (JFET) is difficult to achieve stable amplification with the chopper technology. This paper proposes a low noise amplifier (LNA) with chopper technology based on feedback adjustment. The LNA reduces the turning frequency of the circuit, and maintains the JFET static point. At 375mHz, its noise is 2.55nV/Hz .