应用于可穿戴式智能设备的MEMS电容型传感器信号调理集成电路研究

“Wearable Smart Device” is applying the wearable technology on the daily wear to do the intelligent design and develop the wearable smart devices. Its essence is allowing a variety of MEMS sensors to realize the motion tracking, data collection, information transmission and interaction. So the design of an information collection platform, which should be low cost, low power, high performance, and fully compatible with a variety of MEMS sensors, becomes the core technology of “Wearable Smart Device”. This research project will investigate the design of a low power, high precision and fully compatible signal conditioning integrated circuit for MEMS capacitance sensor, which has the following key characteristics to be well applied in the “Wearable Smart Device”: (1) Fully Compatible: supporting all kinds of MEMS capacitance sensors, which has a pF~nF order of magnitude, in the “Wearable Smart Device” platform, including most of measurement configurations on the ‘Unipolar’ and ‘Push-Pull’ type; (2) Low Power: power can reach 10uW with 1mS measurement time configuration, to provide more stand-by time; (3) High Resolution: realizing the accurate detection of aF order of magnitude changes in capacitance and 13 bit linearity under many non-idealities, such as circuit noise, offset, charge injection, and so on. This project will be implemented in 0.18um CMOS technology, the expected results will be so far exceed than the international similar designs in the high compatibility, low power consumption, high precision (linearity) performance, also the circuit Figure-of-Merit (FoM) is expected to improve by an order of magnitude to 100fJ/step, continue to maintain the international advanced level.

“可穿戴式智能设备”的本质是通过各种MEMS传感器让一个个戴在身上的“小东西”实现运动跟踪、数据收集、信息传输和互动。因此设计低成本、低功耗、高性能、可兼容多种MEMS传感器的信息平台成为其核心技术。本项目将研究MEMS电容型传感器信号调理集成电路，使之具备如下关键特性而更好的应用于可穿戴式智能设备：（1）全兼容：支持pF~nF量级各类MEMS传感器在可穿戴式智能设备平台上的全兼容；（2）低功耗：在单次测量时间配置为1mS进行连续转换时，功耗低至10uW，提供更长待机时间；（3）高精度：在电路噪声、失调等非理性因素影响下实现aF量级电容变化值的精确检测，并达到13位的高线性度。本项目将在0.18um CMOS工艺上实现，预期的研究成果将在高兼容性、低功耗、高精度等方面远远胜过国际同类设计，同时电路的优值有望在当前国际最优水平上再提升一个数量级，至100fJ/step，继续保持国际领先水平。

本项目的研究内容是低功耗高精度全兼容型 MEMS 电容型传感器信号调理集成电路，直接针对可穿戴式智能设备等应用。出于低成本及易于与数字电路集成为片上系统芯片等考量，这些电路基于（深）亚微米标准CMOS工艺进行研究与设计。本项目对相关的 MEMS电容型传感器信号调理电路进行了详细的理论分析、电路设计与优化、模拟仿真及流片验证与测试。具体而言，项目实施主要包括了以下三个方面的内容：A.全兼容型（支持pF~nF量级）MEMS电容型传感器信号调理电路的架构研究与设计；B.低功耗设计：更长待机时间；C.高精度：在电路噪声、失调等非理性因素影响下实现aF量级电容变化值的精确检测。. 本项目设计的信号调理集成电路经深圳市计量质量检测研究院测试，实现了以下关键指标，使之居于行业领先水平：.1）绝对电容精度：79aF（均方根值）；.2）测量时间:0.28uS；.3）电容测量精度位数：16.6位；.4）功耗:38.4uW；.5）线性度：12.6位。. 本项目设计的应用于可穿戴式智能设备的MEMS传感器信号采集平台核心芯片可有效地降低对国外产品的依赖，对可穿戴式智能设备的普及、人民生活的便利、国家物联网发展战略等方面有着重要意义。