A high-precision digital interface circuit is achieved for a tunnel magneto-resistance sensor with a high sensitivity and high dynamic range. The analog front-end detection circuit adopts the structure of a current feedback instrumentation amplifier, and a chopper technology and ripple suppression loop are used to improve the performance. In the back-end digital conversion part, a fourth-order fully feedforward sigma-delta modulator is designed, and the chopper circuit is further applied to eliminate the low frequency noise and offset of the first-stage integrator. The measurement results show that with the input equivalent magnetic field signal amplitude of 100 mV centered at 31 Hz, the SFDR of the final digital output stream reaches 95 dB, and the overall power consumption is 30 mW.

实现了具有高灵敏度和高动态范围的隧道磁阻传感器的高精度数字接口电路。模拟前端检测电路采用电流反馈仪表放大器的结构，并采用斩波技术和纹波抑制环路来提高性能。在后端数字转换部分，设计了一个四阶全前馈sigma-delta调制器，并且进一步应用了斩波器电路，以消除第一级积分器的低频噪声和失调。测量结果表明，在以31 Hz为中心的100 mV输入等效磁场信号幅度的情况下，最终数字输出流的SFDR达到95 dB，总功耗为30 mW。