Extracting Behavioral Data from Physical Descriptions of MEMS for Simulation

The work described here deals with the problems of modeling and simulation for MEMS devices. The eventual goal is to produce a top-down MEMS design system similar to today's powerful VLSI design systems. In this work a fixed fabrication process (MUMPS) and a fixed layout tool (L-Edit) are chosen. Thus our efforts are concentrated on reliable simulation of designs and eventual comparison with actual fabricated parts. The cantilever beam is chosen as an example of how extraction from a physical layout may be modeled and interfaced with various simulators.     

Hierarchical Mixed-Domain Circuit Simulation, Synthesis and Extraction Methodology for MEMS

Emerging results for mixed-domain circuit simulation, a component-level synthesis strategy, and a layout extractor is presented for use in design of microelectromechanical systems (MEMS). The mixed-domain circuit representation is based on Kirchhoffian network theory. Micromechanical and electromechanical components may be partitioned hierarchically into low-level reusable elements. The MEMS component-level synthesis approach uses optimization to generate microstructure layout that meets specified performance criteria. A feature-recognition based extractor for verification translates layout geometry into the mixed-domain circuit representation. A common MEMS component, the integrated microresonator, demonstrates the use of these tools. Lumped-parameter MEMS simulation of the resonant frequency matches finite-element analysis to 1% and fabricated resonators match to within 4% of the synthesized performance. Based on this initial work, a hierarchical structured design methodology for integrated microsystems that is compatible with standard VLSI design is proposed.     

MEMS tunable SOI waveguide Bragg grating filter with 1.3 THz tuning range for C-band 100 GHz DWDM optical network

A MEMS tunable integrated waveguide Bragg grating-based filter for C-band optical dense wavelength-division multiplexing (DWDM) network is presented and analyzed in this work. Waveguide Bragg grating being a notch filter in the transmission spectrum is used to realize a tunable filter by varying the applied voltages to the fixed–fixed beam loaded with this grating. The strain across the grating is enhanced by choosing MEMS beam configuration such that the metal electrode is the bottom-most layer of the composite fixed–fixed beam. Device dimensions are chosen to achieve a narrow full width half maximum of 0.77 nm, allowing filtering of adjacent channels of 100 GHz DWDM network. A large Bragg wavelength shift of 10.4 nm (1552.52–1562.92 nm) was achieved at 45.8 V actuation providing tuning for 14 DWDM channels with inter-channel cross talk below ? 21 dB, with tuning range of 1.3 THz.

     

MEMS开关可重构矩形缝隙环天线的设计

提出一种基于MEMS开关的可重构矩形缝隙环天线设计.其关键部件之一是射频微波MEMS开关,选取了接触式MEMS开关.该天线为用共面波导馈电的多频率可重构天线,通过多个MEMS开关来改变矩形缝隙环天线的拓扑结构,按照一定的规则控制开关可实现多频率可重构.其结构简单,剖面低,易于与电路集成.     

基于锆钛酸铅的低电压驱动MEMS电场传感器研究

该文提出一种基于锆钛酸铅(PZT)的低电压驱动微机电系统(MEMS)电场传感器。该传感器基于电荷感应原理,其敏感单元由固定电极和可动电极构成。固定电极与可动电极均为感应电极,同时两者又是屏蔽电极。在PZT压电材料的驱动下,可动电极产生垂直于敏感芯片基底的振动并且与固定电极形成交互屏蔽,当存在待测电场时,分别在可动电极和固定电极上产生相位差为180°的感应电流信号。该文进行了传感器的设计和有限元仿真,提出敏感微结构的加工工艺流程,突破了基于PZT压电材料的可动电极MEMS工艺兼容制备技术,完成了敏感芯片制备,对传感器进行了性能测试。该传感器具有工作电压低的突出优点。实验测试表明,在0～50 kV/m电场强度范围内,采用1 V交流驱动电压,电场传感器的灵敏度为0.292 mV/(kV/m),线性度为2.89%。     

MEMS CAD系统IMEE的研究和开发

IMEE是一个自主研发的MEMSCAD系统 ,它包括节结点化的系统设计功能、工艺编辑、设计和三维模拟功能、参数化版图单元的版图设计功能等。该系统的最大特点是以工艺为主线 ,贯穿整个设计过程 ,重点解决MEMS设计与工艺脱节的问题 ,实现MEMS工艺设计和在线模拟。另外 ,该系统是跨平台的 ,即适用于UNIX也适用于WINDOWS操作系统 ,对其他MEMSCAD软件具有很好的兼容性 ,还支持用户自主扩展其他功能模块。     

Novel Logarithmic Active Pixel Sensor with High Dynamic Range and High Output Swing

The logarithmic response complementary metal oxide semiconductor （CMOS） image sensor provides a wide dynamic range, but its drawback is the lack of simple fixed pattern noise（FPN） cancellation scheme. Designed is a novel logarithmic active pixel sensor（APS） with high dynamic range and high output swing. Firstly, the operation principle of mixed-model APS is introduced. The pixel can work in three operation modes by choosing the proper control signals. Then, FPN sources of logarithmic APS are analyzed, and double-sampled technique is implemented to reduce FPN. Finally, according to the simulation results, layout is designed and has passed design rule check（DRC）, electronic rule eheck（ERC） and layout versus schematic（LVS） verifications, and the post-simulation results are basically in agreement with the simulation results. Dynamic range of the new logarithmic APS can reach about 140 dB; and the output swing is about 750 inV. Results show that by using double sampled technique, most FPN is eliminated and the dynamic range is enhanced.     

微机电系统计算机辅助设计的研究

微机电系统(MEMS)的计算机辅助设计(CAD)是MEMS实现商品化的重要基础。文章介绍了MEMSCAD的概况和技术特点，提出了一种MEMSCAD的典型体系结构和MEMS建摸与模拟的层次，重点研究了微机电系统中的耦合场分析和宏模型与系统级模拟等关键问题。     

地震勘探用电容式闭环微加速度计的仿真

MEMS加速度传感器大幅提高了新型地震检波器的各项性能指标。利用有限元软件AN-SYS建立了悬臂硅梁的力学模型,并通过其力学性能仿真,得出优化的设计结构尺寸,即梁长L=150μm,梁宽b=40μm,梁厚h=4μm,活动电极和固定电极的间距d0取为1μm。同时利用电路仿真软件建立了传感器闭环系统的整体仿真数学模型,仿真结果表明其阶跃响应和正弦响应基本和理论分析结果吻合,传感器的分辨率可达0.001 m/s2,频带宽度可达500 MHz。该基于MEMS加速度传感器的新型地震检波器在地震勘探中将具有广阔的应用前景。     

基于MEMS共面波导腔的带阻滤波器的设计

应用计算机辅助设计了一种基于共面波导结构的MEMS带阻滤波器.研究了微尺度电磁学、力学、温度等效应.利用ANSOF的HFSS软件模拟分析了滤波器的损耗参数,并应用ANSYS软件分析复合结构的热应力分布,得出了阻带中心频率在18GHz的MEMS带阻滤波器件,提供了一些有意义的理论分析及应用.     

MEMS工艺集成化设计及其可视化

针对目前MEMS设计复杂 ,直观性差等问题 ,提出了工艺集成化设计和可视化的可行性解决方案 ,对其中的关键技术进行了研究 ,并基于所提出的方案研究了工艺设计的集成化和可视化的实现技术。首先对MEMS表面加工工艺进行了详细的分析 ,采用面向过程的方法建立了表面工艺过程的统一模型。基于这一模型 ,研究了MEMS工艺设计的集成化技术 ,实现了工艺设计中各种信息的集成化 ,并设计开发了工艺设计的集成化软件环境。最后 ,对工艺设计中的二维版图的三维重构算法进行了详细的研究 ,通过SolilWorksAPI接口的开发 ,在SolilWorks的环境下实现了工艺过程的三维可视化     

五位分布式MEMS传输线移相器的优化设计

通过在共面波导传输线上周期性地加载分布电容,外加驱动电压改变电容值,实现分布式MEMS传输线移相器。从三个方面优化了五位分布式MEMS传输线移相器的设计:一是分别设计了11.25°和22.5°两种微桥,单元在Ka波段的插入损耗均大于-0.8 dB,回波损耗均小于-15 dB,相移精度小于0.4°,新的五位移相器以2种单元、19个微桥的结构替代了传统单一单元、31个微桥的结构,可减少微桥的总数;二是CPW传输线采用折叠布局,通过共用部分地线,移相器平面尺寸减小至1.81 mm×3.84 mm,相比传统五位分布式移相器,面积减小了56%,实现了器件的小型化;三是设计了一种新型的直流偏置结构,结构简单、工艺容易实现。     

Yield analysis for self-repairable MEMS devices

In this paper, yield analysis for a self-repairable MEMS (SRMEMS) accelerometer design is proposed. The accelerometer consists of (n  +  m) identical modules: n of them serve as the main device, while the remaining m modules act as the redundancy. The yield model for MEMS redundancy repair is developed by statistical analysis. Based upon the yield model, the yield increase after redundancy repair for different m and n numbers is analyzed. ANSYS Monte Carlo simulation is used to estimate the yield of BISR/non-BISR MEMS devices with random point-stiction defects. The simulation results are in good agreement with the theoretical prediction based on our yield model. The simulation results also show that the SRMEMS leads to effective yield increase compared to non-BISRS design, especially for a moderate initial yield.     

Finite Element Simulation of Frequency Response of MEMS-Microphone

The frequency response of a MEMS microphone is largely dependent on the design and size of the package. The location and size of the acoustic port, the dimensions of the front and back chamber, and the packaging material are of key importance. In this paper we present the results of calculating the frequency response of a MEMS microphone obtained by finite element modeling (FEM) for two main types of packaging with different positions of the acoustic port. The simulation results are analyzed and compared to the measured frequency response of the MEMS microphone.     

交指型MEMS滤波器的优化设计

交指型微机电系统(MEMS)滤波器是采用MEMS工艺制备出的交指型结构滤波器,针对交指型MEMS滤波器电磁优化算法中存在速度慢,占用计算资源大等问题,对交指型MEMS滤波器优化设计方法进行了研究。采用主动空间映射算法,在ADS和HFSS软件中建立滤波器电路结构模型和三维结构电磁模型,并分别将它们用于主动空间映射算法所需的粗糙仿真和精确仿真,仅进行了5次精确仿真就完成了一款Ku波段滤波器的优化设计。结果表明,设计的滤波器中心频率为14 GHz,顶部损耗为1.6 dB,-1 dB带宽为2.2 GHz,满足设计指标要求,同时验证了优化设计方法的可行性。     

CMOS layout design of the hysteresis McCulloch-Pitts neuron

A McCulloch-Pitts neuron is the simplified neuron model which has been successfully used for many optimisation problems. The neural network with the hysteresis property can suppress the oscillatory behaviours of neural dynamics so that the convergence time is shortened. In this paper, digital CMOS layout design of the hysteresis McCulloch-Pitts neuron is presented. Based on simulation results using the hysteresis McCulloch-Pitts binary neuron model, a 6-bit fixed point 2's complement arithmetic was adopted for the calculation of the input U of each neuron. Each neuron needs 204 transistors and requires a 399 lambda *368 lambda layout area using the MOSIS scalable CMOS/bulk (SCMOS) VLSI technology with 2 mu m rule of P well, double level metal. Layout design of the hysteresis McCulloch-Pitts neuron chip was completed, and fabrication of the chip and the design for the test circuit for the fabricated CMOS VLSI chip are underway at present.<>     

热致封装效应对MEMS固支梁谐振频率的影响

MEMS器件的封装效应显著而复杂,其中由贴片封装引起的结构热失配是封装效应的主要成因.论文在前期封装-器件耦合行为模型的基础上,利用激光多普勒测振仪实验验证了贴片工艺的热致封装效应对固支梁器件性能的影响.结果表明,贴片前后固支梁的谐振频率发生显著变化,并沿芯片表面表现出明显的分布特征.考虑封装效应的理论模型可以较好地预测该结果,为MEMS系统的器件-封装协同设计提供理论指导.     

射频MEMS封装技术

MEMS在射频(RF)应用领域表现出的低功耗、低损耗和高数据率的优越特性为RF无线通信系统及其微小型化提供新的技术手段。在产品设计的初期阶段,RF MEMS封装的设计考虑是降低成本、提高产品合格率的有效途径。我们主要针对当前RF MEMS器件与电路设计制造中突出的问题——封装技术进行研究,指出封装在产品设计中的重要地位和技术实现方法,特别介绍了计算机仿真在RF MEMS器件与电路封装中的作用。     

多层梁机电耦合系统的等效电路宏模型

实现MEMS器件系统级模拟的关键是建立其宏模型。由单层梁构成的机电耦合系统的等效电路宏模型 ,已做过深入的研究 ,但实际的MEMS器件通常都是多层的 .本文提出了一种基于力 电压 (F V)类比的、适用于由多层梁构成的机电耦合系统的等效电路宏模型 ,该模型可进行小信号时域和频域分析 ,能为多层梁机电耦合系统的设计带来很大的方便。模拟结果表明 ,该模型具有较高的精度