DOI: 10.1109/TIE.2023.3342278

Abstract

    This paper proposes a high-quality ratio-metric measurement (HQRM) method based on analog-to-digital converter (ADC) for high-precision sensors, which shows significant improvement in resolution and stability as well as the sensor’s ability to adapt to rapidly changing experimental environments. The traditional ratio-metric measurement (TRM) method based on ADC is introduced in detail for comparison. Circuits of the two ratio-metric measurement methods are designed and tested, and the experimental results show that the HQRM has much better suppression capability to the output noise and drift caused by the excitation source compared with the TRM. A precision capacitive displacement sensor with the two ratio-metric methods is tested as an example, it is found that the sensor’s output noise and drift caused by the excitation source are significantly better suppressed with the HQRM in the full bandwidth range and the full-scale range, so the resolution of the sensor is improved from 3.79 nm(rms) to 1.51 nm(rms), the temperature drift is reduced from 0.75 nm/°C to nearly zero even with drastic temperature changes. Furthermore, this method is expected to function efficiently for other amplitude-modulated types of high-precision sensors.

文章摘要

提出了一种基于模数转换器(analog-to-digital converter, ADC)的适用于高精度传感器的高质量比例测量(high-quality ratio-metric measurement, HQRM)技术，该技术显著提高了传感器的分辨率和稳定性，以及传感器对快速变化的测试环境的适应能力。作为对比，本文还详细介绍了传统的基于ADC的比例测量(traditional ratio-metric measurement ，TRM)技术。首先设计并测试了这两种比例测量技术对激励源引起的输出噪声的抑制能力。然后以精密电容位移传感器为例，测试这两种比例测量技术对传感器系统中电压基准源的噪声和漂移的抑制能力，实验结果表明，HQRM技术在全带宽范围和全满量程范围内很好地抑制了由电压基准源引起的传感器的输出噪声和漂移，使传感器的分辨率由3.79 nm(rms)提高到1.51 nm(rms)，即使在温度剧烈变化的情况下，温度漂移由0.75 nm/℃降低到接近于零。此外，该方法有望有效地用于其它调幅类型的高精度传感器。

图片摘要

以高精密电容位移传感器为例，相比TRM技术，HQRM技术可以在传感器的全量程和全带宽范围内抑制传感器的噪声和漂移。传感器输出噪声由-130 dB抑制到-150 dB，相应地，分辨率由3.79 nm提升至1.51 nm。在温度变化的频率为0.2 Hz，峰峰值约为35℃的剧烈变化的情况下，传感器的温度漂移从0.75 nm/℃降低到接近于零（淹没于噪声中）。

1）电容位移传感器全量程和全带宽内的噪声抑制

图1：传感器在满量程位置处的输出噪声 

图2：传感器在满量程位置处的输出噪声频谱图

图3：传感器在不同满量程位置的输出噪声。

2）电容位移传感器全量程和全带宽内的温漂抑制

图4：传感器电压基准源的振幅漂移和温度变化。

图5：传感器在满量程位置附近的输出漂移。

图6 传感器在不同满量程位置的输出漂移。

亮点

本文提出了一种基于ADC的高质量比例测量技术，该技术通过调整ADC参考输入端和信号输入端的RC低通滤波器带宽相等，很好地抑制了用于产生正弦信号和参考电压的直流电压基准源的噪声与漂移，从而实现了对正弦信号和参考电压的噪声与漂移的同时抑制。