DIO: 10.1109/TIM.2022.3156975

Abstract

This paper proposes a synchronous demodulation method based on gated integrator for precision sensors, which shows significant improvement in signal-to-noise ratio (SNR) and resolution. Several traditional demodulation methods are introduced, especially the lock-in amplifier in detail for comparison. Through a comprehensive analysis of the gated integrator, it is proved that the proposed method shows a larger useful signal output with similar noise suppression capability compared with the lock-in amplifier so a better SNR could be obtained. Circuits of the two demodulation methods are manufactured and tested, and the results show that the output characteristic of the proposed method is consistent with the theoretical analysis. A precision eddy current displacement sensor prototype with the two demodulation methods is designed and tested as an example. It is found that the resolution of the sensor is improved with the proposed method by about 0.4 bits. Furthermore, this method is expected to function efficiently for any precision sensor requiring synchronous demodulation.

文章摘要

  本文提出了一种基于门控积分器的精密传感器同步解调方法，该方法在信噪比（SNR）和分辨率方面都有显著提高。文章中介绍了几种传统的解调方法，如锁定放大器，并将提出方法与之进行了详细的比较。通过对门控积分器的综合分析，证明了与锁相放大器相比，该方法具有更大的有用信号输出和类似的噪声抑制能力，因此可以获得更好的信噪比。文中对两种解调方法的电路进行了制作和测试，结果表明，该方法的输出特性与理论分析一致。作者设计并测试了两种解调方法的精密电涡流位移传感器样机，测试结果表明，该方法使传感器的分辨率提高了约0.4位。这种解调方法有望在任何需要同步解调的精密传感器上有效运行。

图片摘要

  本文中提出的解调方法由于主要积分自有用信号的一部分（由占空比决定），而不是全部（如相敏检波）。由于主要是对波形幅值较大的部分进行积分，因此输出信号的有效值更大。同时可以证明对于噪声的抑制，本方法与相敏检波有基本相同的抑制能力。因而本方法可以获得更高的输出信噪比。

亮点：

  提出利用门积分器电路对输入正弦信号进行解调，可以获得更高的输出信噪比。