Lateral MEMS microcontact considerations

A lateral switching relay structure has been developed which provides a double gold contact with as low as 70-mΩ measured contact resistance, 0.45-A current-carrying ability at MEMS compatible force levels, TTL compatible actuation, and air gap isolation when open. The die area used for the relay mechanism itself (distinct from the actuation) is approximately 75 μm by 100 μm and was designed to allow fabrication of the relays in the MCNC MUMP's dual polysilicon foundry process with no assembly. Design analysis shows that substantial characterization is needed to design optimal microrelays. Temperature softening and failure modes have been characterized by current voltage techniques. Polysilicon vernier structures were used to develop force/current/conductance curves. Relays using thermal actuators have been built     

MEMS集成滤波器技术

滤波器是频率转换系统(如,调谐电路、接收器)的基本构成模块。借助于MEMS技术实现的滤波器不仅带来插入损耗、功耗、线性等性能的改善,也有利于将整个通信前端集成到单一芯片上。综述了MEMS可调滤波器的研究进展。与单一利用MEMS电容的调变实现频率可调的滤波器相比,分形可调MEMS滤波技术有更小的插入损耗和更宽的调频范围。     

Design and process considerations for fabricating RF MEMS switches on printed circuit boards

Design considerations and process development for fabricating radio frequency microelectromechanical systems (RF MEMS) switches on microwave laminate printed circuit boards (PCBs) are presented in details in this work. Two key processes, high-density inductively coupled plasma chemical vapor deposition (HDICP CVD) for low-temperature silicon nitride deposition, and compressive molding planarization (COMP) have been developed for fabricating RF MEMS switches on PCB. The effects of process conditions of HDICP CVD on low-temperature nitride film are fully characterized for its use in RF MEMS switches on PCB. Not only can COMP planarize the surface of the photoresist for lithographic patterning over topologically complex surfaces, but also simultaneously create a membrane relief pattern on the surface of a MEMS structure. Several membrane-type capacitive switches have been fabricated showing excellent RF performance and dynamic responses similar to those on semiconductor substrates. This technology promises the potential of enabling further monolithic integration of switches with other RF components, such as antennas, microwave monolithic integrated circuits (MMICs), phase shifters, tunable filters, and transmission lines on the same PCBs reducing the losses due to impedance mismatching from components/system assembly and simplifies the design of the whole RF system. [1416].     

基于粒子滤波的声源定位方法

针对噪声与混响环境下的声源定位问题,采用了一种基于粒子滤波的麦克风阵列的声源定位方法。在粒子滤波框架下,将到达麦克风的语音信号作为观测信息,通过计算麦克风阵列波束形成器的输出能量来构建似然函数。实验结果表明,方法提高了声源定位系统的抗噪声与抗混响能力,即使在低信噪比强混响的环境下也能获得较高的定位精度。     

Essential design and fabrication considerations for the reliable performance of an electrothermal MEMS microgripper

Microsystem Technologies - Over the past years, microelectromechanical systems (MEMS) have become a vital component within a wide range of technologies, making the study of their performance and...     

Design considerations for MIS in an Executive MBA program

Executive education courses are typically decision making and policy oriented. This paper suggests and empirically evaluates such an introductory MIS course suitable for an Executive MBA program (EMBA). The analysis reported here should be helpful to any educator teaching or preparing to teach MIS to executives. The evaluation indicates that executives seek both a hands-on educational experience with selected MIS technologies as well as a conceptual framework for managing and using MIS. Although not all MIS topics are deemed relevant, executives develop a strong need to insure a proper organizational direction for MIS activities. They are most concerned with understanding and controlling the evolution and rapid changes of MIS and look for ways that MIS can help them cope with change. For this reason, a successful course pedagogy includes joint case analysis with functional or technique courses in the overall curriculum.     

应用于MEMS陀螺仪的SoC设计

为了解决微电子机械系统(MEMS)陀螺仪体积较大、冗余的计算资源浪费等问题,对Cortex-M3内核的数据处理能力及总线架构进行了研究,设计了一款应用于MEMS陀螺仪的智能化、小型化、低功耗的片上系统(SoC);通过分析温度对陀螺输出信号的影响,对MEMS陀螺温度误差的智能化补偿方式进行了研究,采用以Cortex-M3为核心与电容/电压转换电路、模数转换器(ADC)等模块进行集成化设计的方法,在实现同样功能的情况下减小了陀螺体积;结合MEMS陀螺仪对信号处理资源的要求对存储空间及通信接口进行配置,采用0.18 μｍ BCD加工工艺对SoC进行设计制作;测试结果表明,针对MEMS陀螺仪进行匹配设计的SoC对陀螺输出信号进行温度补偿处理后,全温度区间(-40 ℃～85 ℃)零偏变化量由3.147°/s降低到0.035°/s,显著提升了MEMS陀螺仪的全温测量精度。     

MEMS传感器的惯性测量模块的设计与初始校准

设计了一种基于微机电系统(MEMS)传感器的惯性测量模块,它包括三轴加速度计、三轴陀螺和三轴磁阻传感器。这种惯性测量模块具有体积小、功耗低、成本低的优点,可以方便地用在微小机器人定位系统以及空中机器人控制系统中。详细分析了模块的误差来源,提出了模块中三轴加速度计的非正交误差模型。并运用基于Newton迭代的方法实现了一种自动初始校准算法。实验结果表明:这种自动初始校准算法可以有效地消除该模块的固定偏差、比例误差和非正交误差。     

Design and fabrication of microtunnel and Si-diaphragm for ZnO based MEMS acoustic sensor for high SPL and low frequency application

The purpose of the paper is to design and fabricate a ZnO-based MEMS acoustic sensor for higher sound pressure level (SPL) measurement in the range of 120–200 dB and low frequency infrasonic wave detection. The thickness of silicon diaphragm was optimized for higher SPL using MEMS-CAD-Tool COVENTORWARE. The microtunnel which relates the cavity to the atmosphere was designed and simulated analytically for low cut-off frequency of the sensor in infrasonic band. The resonance frequency of the sensor was obtained using modal analysis. The sensitivity of the sensor was also estimated using COVENTORWARE. The optimized Si-diaphragm thickness for the intended SPL range was determined and found to be 50 μm. The lower cut-off frequency of the sensor for a 10 μm-deep microtunnel was found to be 0.094 Hz. The resonance frequency of the sensor was obtained using modal analysis and found to be 78.9 kHz. Based on simulation results, the MEMS acoustic sensor with 10 μm-deep microtunnel was fabricated. The optimum sensitivity of sensor was calculated using simulated results and found to be 116.4 μVolt/Pa. The lower cut-off frequency of the sensor can be utilized to detect low frequency sounds. The high SPL sensing capability of the device up to 200 dB facilitates detection of high sound pressure level in launch vehicles, rocket motors and weapons’ discharge applications.     

一种用于空投翼伞雀降时的声波高度计系统设计

针对空投翼伞雀降时的准确测高问题,在分析了现有高度测量设备优缺点的基础上,提出了采用声波高度计来提高高度测量信号的准确度。首先完成了声波高度计系统原理样机的研制,并利用设计的声波高度计系统在室内和室外针对不同反射面分别进行了不同高度情况下的试验研究,多组试验数据事后处理的最大测量误差均值分别为室内的0.326m和室外的0.814m,表明设计的高度计在试验量测范围内,其测量精度可以满足空投的要求。     

Adaptive Kalman filter for MEMS IMU data fusion using enhanced covariance scaling

MEMS (micro-electro-mechanical-system) IMU (inertial measurement unit) sensors are characteristically noisy and this presents a serious problem to their effective use. The Kalman filter assumes zero-mean Gaussian process and measurement noise variables, and then recursively computes optimal state estimates. However, establishing the exact noise statistics is a non-trivial task. Additionally, this noise often varies widely in operation. Addressing this challenge is the focus of adaptive Kalman filtering techniques. In the covariance scaling method, the process and measurement noise covariance matrices Q and R are uniformly scaled by a scalar-quantity attenuating window. This study proposes a new approach where individual elements of Q and R are scaled element-wise to ensure more granular adaptation of noise components and hence improve accuracy. In addition, the scaling is performed over a smoothly decreasing window to balance aggressiveness of response and stability in steady state. Experimental results show that the root mean square errors for both pith and roll axes are significantly reduced compared to the conventional noise adaptation method, albeit at a slightly higher computational cost. Specifically, the root mean square pitch errors are 1.1? under acceleration and 2.1? under rotation, which are significantly less than the corresponding errors of the adaptive complementary filter and conventional covariance scaling-based adaptive Kalman filter tested under the same conditions.     

多准则MEMS陀螺随机误差在线建模与实时滤波

针对随机误差相关性较弱的MEMS陀螺仪,提出采用多准则曲线方法辨识其带有截距项的随机误差时间序列模型.采用该模型可直接对MEMS陀螺仪的实测量数据进行在线建模,而无需零均值化离线处理.基于该模型并采用状态扩增的方法设计卡尔曼滤波器,实现了MEMS陀螺仪随机误差的实时滤波.实验结果表明,针对某MEMS陀螺仪带有截距项的AR(2)模型可以作为其随机误差模型,经过在线建模和实时滤波后,MEMS陀螺仪随机误差的标准差降低了50%,有效抑制了MEMS陀螺仪的随机误差.     

Design of MEMS switch for RF applications

Components like passive electronically scanned (sub) arrays, T/R modules, reconfigurable antennas etc., in RF applications are in need of MEMS switches for its re-configurability and polarization. This paper presents the analysis, design and simulation of a MEMS switch. The switch proposed in this paper is intended to work in the frequency range of 4–8 GHz. The proposed switch fulfills the switching characteristics concerning the five requirements loss, linearity, high switching speed, small size/power consumption, low pull down voltage following a relatively simple design, which ensures reliability, robustness and high fabrication yield. The switch implemented in this paper is based on the integration mode of operation and widely used in RF applications.     

导航系统MEMS加速度计的设计

本文介绍了加速度传感器芯片ADXL250在设计导航系统中的加速度计方面的一个应用.文中还介绍了加速度计相关的标定电路.标定前后的实验数据对比表明:用此加速度传感器设计的加速度计体积小、结构简单,精度高,能很好地满足惯性测量和导航系统中加速度的测量.     

Design considerations for knowledge acquisition

Expert systems are commercially becoming more prominent and available as the breadth of applications continues to expand, eventually they could very well become the most integral part of an organization's normal operations. Knowledge acquisition is often found to be the major problem in the development of expert systems. This paper places in order the framework for proper knowledge acquisition to ensure that knowledge which is the key for any expert system is acquired effectively from an expert.     

Robust extended multidelay filter and double-talk detector for acoustic echo cancellation

We propose an integrated acoustic echo cancellation solution based on a novel class of efficient and robust adaptive algorithms in the frequency domain, the extended multidelay filter (EMDF). The approach is tailored to very long adaptive filters and highly auto-correlated input signals as they arise in wideband full-duplex audio applications. The EMDF algorithm allows an attractive tradeoff between the well-known multidelay filter and the recursive least-squares algorithm. It exhibits fast convergence, superior tracking capabilities of the signal statistics, and very low delay. The low computational complexity of the conventional frequency-domain adaptive algorithms can be maintained thanks to efficient fast realizations. We also show how this approach can be combined efficiently with a suitable double-talk detector (DTD). We consider a corresponding extension of a recently proposed DTD based on a normalized cross-correlation vector whose performance was shown to be superior compared to other DTDs based on the cross-correlation coefficient. Since the resulting DTD also has an EMDF structure it is easy to implement, and the fast realization also carries over to the DTD scheme. Moreover, as the robustness issue during double talk is particularly crucial for fast-converging algorithms, we apply the concept of robust statistics into our extended frequency-domain approach. Due to the robust generalization of the cost function leading to a so-called M-estimator, the algorithms become inherently less sensitive to outliers, i.e., short bursts that may be caused by inevitable detection failures of a DTD. The proposed structure is also well suited for an efficient generalization to the multichannel case.     

Multi-level and multi-objective design optimisation of a MEMS bandpass filter

Microelectromechanical system (MEMS) design is often complex, containing multiple disciplines but also conflicting objectives. Designers are often faced with the problem of balancing what objectives to focus upon and how to incorporate modeling and simulation tools across multiple levels of abstraction in the design optimization process. In particular due to the computational expense of some of these simulation methods there are restrictions on how much optimization can occur. In this paper we aim to demonstrate the application of multi-objective and multi-level design optimisation strategies to a MEMS bandpass filter. This provides for designers the ability to evolve solutions that can match multiple objectives. In order to address the problem of a computationally expensive design process a novel multi-level evaluation strategy is developed. In addition a new approach for bandpass filter modeling and optimization is presented based up the electrical equivalent circuit method. In order to demonstrate this approach a comparison is made to previous attempts to design similar bandpass filters. Results are comparable in design but at a significant reduction in functional evaluations, needing only 10,000 functional evaluations in comparison to 2.6 million with the previous work.     

Design considerations for a general-purpose microprocessor

The authors examine the performance, cost, and schedule tradeoffs made for the NS 32532, a 32-bit general-purpose microprocessor. Among its features are a 30-MHz clock frequency, three on-chip caches, a four-stage pipeline, and dedicated mechanisms for multiprocessing support. The authors describe the design constraints set by the VLSI processing and packaging technologies. They address the issue of market requirements by examining the software and hardware considerations for the microprocessor's target applications. After describing the functional partitioning choices, including the means for supporting a memory hierarchy and floating-point operations, they present the NS32532's microarchitecture. They then examine the microprocessor's system interface, the memory reference transactions, and the instruction-flow and data-flow monitoring mechanisms. Finally, the authors present an overview of the methodology adopted to accomplish the design within a strict schedule while achieving full functionality and meeting cost and performance goals     

Design considerations for array processing languages

The Department of Energy (DoE) has a long history of large-scale scientific calculation on the most advanced ‘number-crunching’ computers. Recently, an effort to improve communications and software sharing among DoE laboratories has been underway. One result of this sharing is a project to design and implement a common language. That language turns out to be FORTRAN 77 significantly extended with new data structures, control structures and array processing. The data used to design the array processing feature is surprising and likely to be of use to others working in scientific language design; it is reported here so that others may profit from DoE's experience.