A Capacitance-to-Digital Converter for Displacement Sensing with 17b Resolution and 20µs Conversion Time

📋 论文概要

本文提出一种用于位移传感的电容数字转换器，实现了17位分辨率和20微秒转换时间，满足精密机电系统对亚纳米级动态稳定性的需求。

💡 主要创新点

• 实现了17b的高分辨率电容数字转换，适用于亚纳米级位移传感。
• 在20微秒内完成转换，实现低延迟，适用于实时伺服控制。

🏷 关键词

📄 原文摘要

In precision mechatronic systems, such as wafer steppers, the position of critical mechanical components must be dynamically stabilized with sub-nanometer precision. This can be achieved by a servo loop consisting of a displacement sensor and an actuator. Compared to optical interferometers, capacitive displacement sensors offer smaller size and lower cost. However, mechanical tolerances limit their electrode spacing to about 10µm [1], while the targeted resolution is below 100pmrms. This requires a capacitance-to-digital converter (CDC) with more than 17b resolution. Furthermore, its latency must be low enough (20µs) to avoid compromising servo-loop stability. Lastly, it should be stable enough to maintain measurement accuracy during the intervals between system calibrations. In this paper, we report a CDC with capacitive offset cancellation, which digitizes a 10pF off-chip capacitance (in the presence of a 10pF parasitic capacitance CP

👥 作者与机构

Sha Xia, Kofi Makinwa, Stoyan Nihtianov

Delft University of Technology, Delft, The Netherlands