高精度微弱磁场信号采集系统的设计与实现

微弱磁场测量是研究物质特性和探索未知世界的重要手段之一。实现高精度的微弱磁场信号测量需要设计高精度的信号采集系统，而以模拟量输出的磁强计通常需要数字采集系统进行模/数转换。为此，文章设计开发基于Σ-Δ型模/数转换器（ADC）的高精度微弱磁场信号采集系统，包括系统硬件电路设计和系统核心控制器FPGA的功能设计，实现了FPGA对ADC的读写控制，以及ADC输出数据的接收和发送等。性能测试结果表明，该系统的有效采样位数可接近理论值（21位），输出噪声RMS值为1.9 μV，磁场测量精度满足0.1 nT要求。

Design and implementation of signal acquisition system for high-precision weak magnetic field

The weak magnetic field measurement is one of the important means to study the material properties and to explore the unknown world. For the magnetometer with analog signal output, an A/D converter is needed to support a high-precision signal acquisition system for the high-precision measurement of weak magnetic field signals. Therefore, a signal acquisition system for high precision weak magnetic field is developed based on the Sigma-Delta A/D converter. The system hardware circuit design and the functional design of the FPGA as the system core controller ensure the Read/Write control of the A/D converter by the FPGA, as well as the receiving and the transmission of the ADC output data. Results of the performance test show that the effective resolution of the system can approach the theoretical value of 21bits, with an output RMS noise as low as 1.9 μV and a measurement precision of 0.1 nT, better than the required value.