DOI: 10.1109/TIE.2022.3201344
Abstract
This study presents a high-precision detection method based on biased operational rectifier (BOR) and tracking analog-to-digital converter (TADC) for real-time monitoring of the amplitude drift of sinusoidal excitation signals, which significantly reduces the requirement for ADC's measurement accuracy and improves the signal-to-noise ratio (SNR). BOR modules are proposed innovatively to make the amplitude drift can be detected easily by an ADC with poor precision. Combining with the tracking ADC, the proposed detector could suppress the noise near the cut-off frequency and thus improve SNR. An amplitude drift detector and a lock-in amplifier are designed and tested experimentally. The results show that the voltage resolution of the proposed detector could reach 0.12 ppm for a sinusoidal source with an amplitude of 2.5 V. The SNR is measured 88 dB, which is 8 dB higher than that of the lock-in amplifier. The proposed detector is also applied in a precision capacitive displacement sensor. With the amplitude drift detector, the drift of the capacitive sensor caused by the signal source's amplitude drift could be significantly reduced from 16 nm/°C to 2 nm/°C. Furthermore, this method is also applicable to other amplitude-modulated types of high-precision sensors.
文章摘要
本研究提出了一种基于偏置运算整流器（BOR）和跟踪型模数转换器（TADC）的高精度检测方法，用于实时监测正弦激励信号的幅度漂移。这种方法显着降低了对ADC测量精度的要求并提高了信噪比（SNR）。创新性地提出的BOR模块使得幅度漂移可以很容易地被精度较差的ADC检测到。所提出的检测器通过与跟踪型的ADC相结合可以抑制截止频率附近的噪声，从而提高 SNR。我们设计出了幅度漂移检测器和锁定放大器，并进行了实验测试。实验结果表明：对于振幅为 2.5 V 的正弦源，所提出的检测器的电压分辨率可以达到 0.12 ppm；测得的SNR为88 dB，比锁定放大器高8dB。所提出的检测器还应用于高精度电容式位移传感器中。由信号源的幅度漂移引起的电容传感器的漂移可以在幅度漂移检测器的帮助下从16 nm/°C显著降低到2 nm/°C。此外，该方法也适用于其他调幅类型的高精度传感器。
图片摘要
本文提出的幅值漂移检测器由BOR模块和TADC构成，并形成一个反馈电路结构。这种电路可以在BOR模块里就将微弱信号放大，并利用TADC的检测原理精确的测量出正弦信号的幅值漂移。
在温度变化10℃的情况下，由提出的幅值漂移检测器测得的正弦信号的幅值漂移情况与电容位移传感器的位移漂移表现得非常一致。通过补偿，我们将电容传感器的漂移从16 nm/°C显著降低到2 nm/°C。
亮点
在BOR模块的帮助下，我们使用一个直流参考信号消除了带有漂移的正弦信号幅值中的大的参考值，并只留下漂移了，随后放大和检测。
使用TADC作为数模转换器，构建闭环电路，显著地提高了检测电路的SNR。
在幅度漂移检测器的帮助下，由信号源的幅度漂移引起的电容传感器的漂移从16 nm/°C被显著降低到2 nm/°C。
