Advanced and Intelligent Interface Circuits for Capacitive MEMS Sensors - The E and S in MEMS

适用于电容式 MEMS 传感器的先进智能接口电路 - MEMS 中的 E 和 S

• 批准号: EP/D022711/1
• 负责人: Michael Kraft
• 金额: $ 14.14万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD022711%2F1
• 关键词: Advanced; Intelligent; Interface; Circuits; Capacitive

Micro-electro-mechanical sensors measure quantities such as acceleration, rate of turn, pressure or force by using a tiny silicon proof mass whose position is changed as a response to these quantities. This translates into a change in capacitance, which, in turn, can be measured by electronic circuits. Much effort has been put into improving these sensors by developing new micro-fabrication processes and optimising the design of the mechanical sensing element. This research suggests a radically different approach to improve the performance of these sensors, namely to work on the electronic interface and control systems aspects of these sensors. This is achieved by incorporating the micromachined sensing element in so-called closed loop, force-feedback systems where an electrostatic feedback force is generated that counteracts the motion of the proof mass. The most promising type of control system is based on higher order sigma-delta modulators. Sigma-delta modulators (SDM) are the standard approach for electronic analogue-to-digital conversion. It is proposed here to use similar topologies & architectures and apply them to micromachined capacitive sensors to improve their performance properties such as bandwidth, dynamic range, linearity and noise-floor. A further attractive property is that a SDM has a direct digital output signal that can interface with a standard digital signal processor. A property called noise-shaping is of crucial importance and a measure of how well such a sensor system works. Higher-order SDM, as proposed to be used here in conjunction with MEMS sensors, have much superior noise shaping than lower order ones, which have been researched to date. To achieve this goal it will be necessary to develop new architectures and control system topologies, as a one to one transfer of electronic A/D SDM system architectures to MEMS sensors is not possible. This is a challenging task that will require theoretical analysis involving nonlinear control theory, extensive system level simulation, implementation in hardware and rigorous testing of the sensor.Little research has been done in this direction, yet there is huge potential to make a real impact. With this approach it should be possible to develop a very versatile interface chip that can be used with a range of micromachined capacitive sensors, as it is very tolerant to fabrication variations, which are a problem for many micromachined sensors. We want to demonstrate the validity and potential of this approach using a micromachined accelerometer supplied by our industrial partner Melexis. This reflects the general philosophy behind this research programme, use an existing micromachined sensor, and use advanced electronics and control engineering to make it better, more versatile and easier to integrate at the system level.

微机电传感器通过使用微小的硅质量块来测量诸如加速度、转动速率、压力或力等量，该硅质量块的位置随着这些量的响应而改变。这转化为电容的变化，而电容的变化又可以通过电子电路测量。通过开发新的微制造工艺和优化机械感测元件的设计，已经投入了很多努力来改进这些传感器。这项研究提出了一种完全不同的方法来提高这些传感器的性能，即在这些传感器的电子接口和控制系统方面进行工作。这是通过将微机械感测元件结合在所谓的闭环力反馈系统中来实现的，在闭环力反馈系统中，产生抵消检测质量块的运动的静电反馈力。最有前途的控制系统类型是基于高阶Σ-Δ调制器。Σ-Δ调制器（SDM）是用于电子模数转换的标准方法。这里建议使用类似的拓扑结构和架构，并将其应用于微机械电容传感器，以提高其性能特性，如带宽，动态范围，线性度和噪声地板。另一个有吸引力的特性是SDM具有可以与标准数字信号处理器接口的直接数字输出信号。一个被称为噪声整形的特性是至关重要的，也是衡量这种传感器系统工作好坏的一个指标。高阶SDM，如这里提出的与MEMS传感器结合使用，具有比迄今为止已经研究的低阶SDM优越得多的上级噪声整形。为了实现这一目标，将有必要开发新的架构和控制系统拓扑结构，因为电子A/D SDM系统架构到MEMS传感器的一对一转移是不可能的。这是一项具有挑战性的任务，需要进行涉及非线性控制理论的理论分析、广泛的系统级仿真、硬件实现和传感器的严格测试。在这方面的研究很少，但有巨大的潜力产生真实的影响。通过这种方法，应该可以开发出一种非常通用的接口芯片，该芯片可以与一系列微机械电容传感器一起使用，因为它对制造变化非常宽容，这对于许多微机械传感器来说是一个问题。我们希望使用我们的工业合作伙伴Melexis提供的微机械加速度计来证明这种方法的有效性和潜力。这反映了这项研究计划背后的一般理念，使用现有的微机械传感器，并使用先进的电子和控制工程，使其更好，更通用，更容易在系统层面集成。