电容式微加速度计的噪声分析

噪声是以微弱信号处理为特征的电容式微加速度计性能提高的主要制约因素。针对电容式微加速度计的噪声,详细分析和研究了其特性。首先分析了电容式微加速度计的系统噪声由机械热噪声和电路噪声两部分组成;采用热力学均分理论和集成电路噪声特性分别对机械热噪声和电路噪声进行建模、分析和计算,得到了机械热噪声等效噪声加速度和各级电路的噪声值。然后用自行设计的微加速度计表头和接口电路进行试验,实验结果验证了噪声模型的正确性,确认了电容式微加速度计电容检测电路—电荷放大器是最主要的噪声源。     

非硅MEMS电容式微加速度计的测控电路设计

为了提高MEMS微加速度计的量程和抗过载能力,设计了基于UV-LIGA技术的非硅MEMS电容式微加速度计。针对该加速度计,设计了基于相敏解调的差分电容测控电路。检测通道主要由前置级电荷积分放大电路、带通滤波电路、相敏解调器、低通滤波以及电平转换电路组成,反馈通道由低通滤波和加法电路组成。完成了微加速度计测控电路的调试和检测通道的标定实验,实验表明:检测通道的量程约为±6 pF,灵敏度为89.3 mV/pF,线性度为2.59%,满足加速度计检测通道的要求。     

单载波调制型加速度计差分电容检测电路

单载波调制型差分电容检测电路是为满足微机械加速度计高线性度、高分辨率的需要而设计的,本文给出了检测电路的原理图,分析了寄生电阻、电容模型,从理论上证明该电路可有效消除寄生电阻和电容的影响,并推导了各关键功能模块的传递函数;此外,从电路的各个局部环节研究了会对电路性能造成影响的因素,包括放大电路的噪声源、载波信号稳定性、两路电荷放大器一致性、调制信号与参考信号相位同步等.经理论推导,通过改进和避免不利因素的影响即可保证电路的稳定性,适用于微机械加速度计检测领域.     

差分电容硅微加速度计检测电路研究

针对硅微加速度计中微小差分电容检测,提出了一种基于调制解调方法的闭环检测电路,介绍了该闭环检测系统的原理框图和实现途径。分析了基于单路载波的前置电容-电压( C-V)转换电路,证明了基于相关芯片的解调方法的有效性,其解调效率仅对开环输出有影响;基于双路反馈电路的静电力平衡回路有效提高该检测系统的线性度。结合硅微加速度计参数和电路设计参数,对加速度计系统进行了仿真,仿真结果显示系统稳定,刻度系数为0.9 V/gn 左右,带宽700 Hz左右。结合表头进行的精密转台实验结果表明该加速度计系统刻度系数0.88 V/gn,量程可达±13 gn。     

（中国微米纳米技术学会文章）一种硅微机械结构振动幅度的电学测量方法及实验研究

本文针对硅微机械结构振动幅度由于封装难以计算机视觉测量及电学测量中的精度受接口电路参数影响的问题,在对静电梳齿驱动、平板电容检测的硅微谐振结构进行建模分析后,提出基于单边带电压比的电学测量振动幅度的方法并分析了测量方法的原理。实验表明研制的某硅微机械谐振加速度计在受迫振动下的振动幅度为0.25um,频谱分析还表明存在上电噪声引起的振动幅度,该测试方法还能应用于硅微谐振结构的谐振频率测量,同时为高品质因数的硅微机械谐振结构的可静电自激驱动提供了依据。     

微加速度计启动漂移特性研究与实验

目前研制的基于体硅工艺的微加速度计存在着启动时间较长,启动漂移量较大的问题,难以满足某些需要快速启动的应用.为了减少微加速度计的启动时间,对微加速度计的启动漂移特性进行了研究.分析了启动过程中微加速度计表芯自身发热,驱动和检测电路的发热的热传导和电路参数漂移的影响,并建立了包括电路的微加速度计有限元模型进行热仿真分析,...     

微机械电容式加速度传感器测试电路研究

在测量硅微电容式加速度传感器时,由于器件信号的微弱和寄生电容的干扰,提高加速度的稳定性和分辨率非常困难.针对这种情况,作者分析对比开关性和调制解调型两种常见微弱电容检测方法优缺点,并提出了一种微电容检测的改进电路,用此电路对电容式加速度传感器进行了测试.数据表明,微加速度计灵敏度为1.63 V/gn,可以检测到10-17F量级的电容值.     

电容式微加速度计的刻度温漂的半解析模型

针对电容式微加速度计的刻度温漂,根据微加速度计的检测原理及热变形的分析结果,建立了刻度温漂的半解析模型,并在此基础上分析了刻度温漂的主要影响因素.分析结果表明,刻度温漂由两部分组成,第一部分主要由单晶硅的弹性模量的温度系数决定,可以通过高掺杂降低;第二部分由微加速度计的热变形引起,它的大小与封装胶的弹性模量、梳齿的宽度、大电容间隙与小电容间隙的比值以及固定梳齿锚点的位置相关;第一部分和第二部分分别是正数和负数,因此相互补偿.基于MEMS体硅微加工工艺,制造了微加速度计的实验样品,刻度温漂的测量结果验证了理论分析结果的正确性.     

电容式力平衡加速度计的设计

电容式微机械加速度计是一种将加速度转换成差分电容、通过检测差分电容的变化来检测加速度大小的一类高精度的惯性传感器.利用开关电容电路实现C-V变换,利用反馈静电力实现力平衡闭环控制,设计了一种电容式微机械加速度计.通过构建电容式加速度传感器及外围电路的数学模型,推导了闭环工作的系统函数.并对实际系统进行研制,最后给出了整个系统的测试结果.     

基于Verilog-A的电容式MEMS加速度计模型

本文分析了传统MEMS电容式加速度计模型的不足,根据三明治结构电容式加速度计的特点,考虑了寄生电容和热机械噪声的影响,建立了用Verilog-A硬件描述语言实现的模型。该模型与主流集成电路设计环境相兼容,具有很强的可移植性。模拟验证结果表明,该模型如实反映了MEMS电容式加速度计的工作状态,能够为设计单片集成的微弱电容检测电路提供有效的帮助。     

A monolithic three-axis micro-g micromachined silicon capacitive accelerometer

A monolithic three-axis micro-g resolution silicon capacitive accelerometer system utilizing a combined surface and bulk micromachining technology is demonstrated. The accelerometer system consists of three individual single-axis accelerometers fabricated in a single substrate using a common fabrication process. All three devices have 475-/spl mu/m-thick silicon proof-mass, large area polysilicon sense/drive electrodes, and small sensing gap (<1.5 /spl mu/m) formed by a2004 sacrificial oxide layer. The fabricated accelerometer is 7/spl times/9 mm/sup 2/ in size, has 100 Hz bandwidth, >/spl sim/5 pF/g measured sensitivity and calculated sub-/spl mu/g//spl radic/Hz mechanical noise floor for all three axes. The total measured noise floor of the hybrid accelerometer assembled with a CMOS interface circuit is 1.60 /spl mu/g//spl radic/Hz (>1.5 kHz) and 1.08 /spl mu/g//spl radic/Hz (>600 Hz) for in-plane and out-of-plane devices, respectively.     

声表面波加速度计中压膜阻尼技术的研究

分析论证了压膜阻尼应用于声表面波加速度计的可行性。利用机电模拟方法,建立完整的声表面波加速度计等效电路模型。通过对该模型进行计算机仿真分析,总结出各种压膜阻尼参数影响声表面波加速度计性能的规律,从而为声表面波加速度计的设计提供重要的理论依据。     

用于高速旋转载体的惯性导航系统设计

针对高速旋转载体的实际应用情况,采用了无陀螺捷联惯性导航技术方案,快速精确测量载体的姿态、速度和位置信息。无陀螺捷联惯导系统采用加速度计来解算载体相对惯性系的角速度,从而代替角速度陀螺仪,提高了系统的高过载的适应能力。首先推导了一种基于六加速度计配置方式力学编排方程,分析了加速度计精度、杆臂长度以及时间等因素对角速度误差产生影响,最后仿真分析了加速度计精度对惯导系统的定位精度的影响,为系统设计提供理论依据。     

Placement of Accelerometers for High Sensing Resolution in Micromanipulation

High sensing resolution is required in sensing of surgical instrument motion in micromanipulation tasks. Accelerometers can be employed to sense physiological motion of the instrument during micromanipulation. Various configurations of accelerometer placement had been introduced in the past to sense motion of a rigid-body such as a surgical instrument. Placement (location and orientation) of accelerometers fixed in the instrument plays a significant role in achieving high sensing resolution. However, there is no literature or work on the effect of placement of accelerometers on sensing resolution. In this paper, an approach of placement of accelerometers within an available space to obtain highest possible sensing resolution in sensing of rigid-body motion in micromanipulation tasks is proposed. Superiority of the proposed placement approach is shown in sensing of a microsurgical instrument angular motion by comparing sensing resolutions achieved as a result of employing the configuration following the proposed approach and the existing configurations. Apart from achieving high sensing resolution, and design simplicity, the proposed placement approach also provides flexibility in placing accelerometers; hence it is especially useful in applications with limited available space to mount accelerometers.     

无陀螺导弹姿态测试系统的设计

由于陀螺仪和加速度计组成的传统导航系统难以应用在高速旋转的飞行体姿态测试中,设计了由MEMS加速度计和地磁传感器构成无陀螺测试系统。介绍了总体电路的设计思想,并说明了复杂可编程逻辑器件(CPLD)控制A/D采样和数据存储的策略。通过模拟转台上不同情况下的实际测量证明:此电路完全满足三维姿态测试的设计要求,并能得到良好的测试波形。     

太阳能光伏-热伏发电板的自适应追光系统设计与实现

在小型太阳能光伏-热伏发电系统中,为了提高其发电效率,通常会辅以自动追光系统;针对现有的基于多光电二极管的自动追光系统结构复杂等问题,提出了一种基于光敏电阻的自适应追光系统;为了实现发电板对光源的追踪,采用了基于负反馈的自适应追光原理,通过软件设计控制追光精度,同时增加了系统位置消抖控制;在硬件方面,采用光敏电阻感应光强,借助AD转换电路和舵机,以驱动太阳能光伏-热伏发电板转动直至发电板平面垂直于太阳光;优化设计了光敏电阻与板面的夹角大小以调整追光的区域及误差;最后完成了整体装置的机械结构设计和电路图设计及仿真;结果表明,与现有的多光电二极管追光系统相比,所设计的追光系统机械装置部分的设计更加简单,便于实现,同时通过优化设计改善了追光的稳定性。     

Digital stabilization of motion of precision controlled base platforms with inertial sensitive elements. II. Application of float angular velocity sensor and pendulum accelerometers

Problem of synthesis of digital control system for a new-generation broad-band calibration testbed, operating in two regimes, is considered. The first low-velocity regime uses gyroscopic (float) angular velocity sensor together with the system of pendulum accelerometers, measuring tangential accelerations of the points of their attachment to the platform. The second high-velocity regime uses pendulum accelerometers only, part of these accelerometers recording tangential accelerations, and the other part, centrifugal accelerations. Similar to [1], the problem is connected with finding digital control algorithms realized in one processor which determine controllers of auxiliary loops (for angular velocity sensors and accelerometers) and the controller of the main loop (stabilization circuit) providing stabilization of the given motion of the controlled base platform. Solution to this problem is given; this solution represents the method for synthesis of such systems; analysis of obtained solution in the temporal and frequency domain is performed.     

Sub-Micro-Gravity In-Plane Accelerometers With Reduced Capacitive Gaps and Extra Seismic Mass

This paper presents a robust fabrication technique for manufacturing ultrasensitive micromechanical capacitive accelerometers in thick silicon-on-insulator substrates. The inertial mass of the sensor is significantly increased by keeping the full thickness of the handle layer attached to the top layer proof mass. High-aspect-ratio capacitive sense gaps are fabricated by depositing a layer of polysilicon on the sidewalls of low aspect- ratio trenches etched in silicon. Using this method, requirements on trench etching are relaxed, whereas the performance is preserved through the gap reduction technique. Therefore, this process flow can potentially enable accelerometers with capacitive gap aspect-ratio values of greater than 40:1, not easily realizable using conventional dry etching equipment. Also, no wet-etching step is involved in this process which in turn facilitates the fabrication of very sensitive motion sensors that utilize very compliant mechanical structures. Sub-micro-gravity in-plane accelerometers are fabricated and tested with measured sensitivity of 35 pF/g, bias instability of 8 mug, and footprint of <0.5 cm².     

基于S3C2410的超声造影剂震荡仪的设计

针对传统声振式造影剂制备方法的缺陷．提出一种基于嵌入式的小型系统设计方案。文中在机械振荡法原理的基础上．结合现代电路设计出以ARMS3C2410处理器为核心．电阻式触摸屏为输入的机械式硬件电路。并详细阐述系统工作原理、硬件结构和相关驱动程序。试验结果表明,系统操作方便．具有良好的人机界面,能够制备粒径分布均一,性质稳定的超声造影剂。该设计是一种新型超声造影剂制备方法．对目前造影剂制备技术的研制提供了一种有效的手段．并有望实现商品化．     

Design of an SOI-MEMS high resolution capacitive type single axis accelerometer

In recent years, high resolution micro accelerometers are increasingly finding various applications in different segments of life. The current work deals with the design of a high resolution single axis accelerometer based on SOI-MEMS technology. Accordingly two different approaches for designing comb type, capacitive, SOI-MEMS accelerometer is presented. Initially a system level approach using a simulation platform from SABER is carried out to obtain the basic design. Later, a device level design is carried out by building three dimensional (3D) geometric models using finite element (FE) simulations through CoventorWare software. Different design parameters like mechanical and electrical sensitivity, capacitance values, resonant frequency, etc. are obtained in either of the cases and compared. The design is optimized based on the overall sensitivity and the system noise level both electrical and mechanical, respectively. The complete design is worked out in accordance with the silicon on insulator based multiuser MEMS fabrication processes (MUMPs) technology from MEMSCAP foundry.