基于绝缘液体充填封装RFMEMS开关特性分析

提出并设计一种采用绝缘液体充填封装的RF MEMS开关,分析其工作原理,并以高压油、蓖麻油、甘油为绝缘液体充填封装,仿真分析绝缘液体对RF MEMS开关的驱动电压、冲击速度、响应时间、开关电容等方面的影响。结果表明:绝缘液体充填封装有效地将驱动电压降为原来的1/εr,降低上极板对下极板的冲击速度。对3种液态封装材料性能分析,蓖麻油效果最好:阈值电压下降了一半,约为10 V;当驱动电压为20 V时,响应时间为40.6μs,优于高压油(91.3μs)、甘油(89.9μs),冲击速度约为1.26 m/s。     

低驱动电压k波段电容耦合式RFMEMS开关的设计

设计了一种低驱动电压的电容耦合式射频微机械(RF MEMS)开关.RF MEMS开关采用共面波导传输线,双电极驱动,悬空金属膜采用弹性折叠梁支撑.使用MEMS CAD软件CoventorWare、微波CAD软件HFSS,分别仿真了开关的力学性能和电磁性能,仿真结果表明:开关的驱动电压为2.5V,满足低驱动电压的设计目标;开关开态的插入损耗约为0.23 dB@20 GHz,关态的隔离度约为18.1 dB@20 GHz.最后给出了这种RF MEMS开关的微制造工艺.     

基于共平面波导的可调低通滤波器的设计和制作

介绍了一种使用多触点MEMS开关实现的新型可调微波MEMS低通滤波器,应用MEMS制作工艺在石英衬底上实现滤波器结构.滤波器基于慢波共平面波导周期性结构,具有尺寸小、插损低、可与单片微波集成电路工艺兼容等优点.滤波器截止频率的大小取决于MEMS开关的状态.实验结果表明,当MEMS开关受到激励时,低通滤波器的3-dB截止频率从12.5GHz转换至6.1GHz,带内纹波小于0.5dB,带外抑制大于40dB,开关的驱动电压在25V左右.     

RF MEMS开关的静电斥力驱动研究

针对射频微机电系统(RF MEMS)开关工作时因介质充电而发生“粘连”失效的问题,提出了利用静电斥力驱动替代传统的静电引力驱动方式,使RF MEMS开关在工作时介质层不存在电势差,从根源上消除介质充电.通过COMSOL仿真软件,分析了静电斥力的产生机理,重点探究了静电斥力驱动结构中尺寸参数对可动极板位移的影响,并通过结构优化有效降低了驱动电压,为开关后续设计提供了参考.     

宽带直接接触式RF MEMS开关

本文提出一种静电驱动直接接触式宽带MEMS开关,包含CPW传输线、双U型金属悬臂梁、触点和锚区,兼顾了开关接触可靠、克服微结构粘连和低驱动电压三大结构可靠性设计因素。本开关为三端口开关,使用低温表面微机械工艺,制作在400μm厚的高阻硅衬底上,芯片尺寸0.8mm×0.9mm。样品在片测试结果表明,在6GHz频点,开关本征损耗0.1dB,隔离度24.8dB,等效开关接触电阻0.6Ω,关态电容6.4fF,开关时间47μs,开关驱动电压为20-60V。     

基于CMOS的开关电容DC-DC降压变换器

在标准CMOS工艺的基础上,分析了基本串并电容组合开关电容DC-DC降压变换器的工作原理和集成方法.采用两个单端开关电容变换器反相并联联结,降低了输出电压波纹.利用电路内部节点电压驱动MOS开关管,避免了每个开关管都必须单独驱动.用SPICE软件对电路进行了瞬态分析,给出了分析结果.     

欧姆接触式RF MEMS开关设计与仿真

利用表面微加工工艺设计了一种双悬臂梁支撑的欧姆接触式MEMS开关,开关的材料为Au。通过对开关驱动电压的理论分析得出,悬臂梁的刚度越低,下拉电压就会越小;又因为刚度与悬臂梁厚度的三次方呈比例,所以,降低刚度最有效的办法就是减少梁的厚度。通过对开关的性能仿真发现:开关的闭合电压为44V;触点的接触力为22.45μN;谐振频率为25.5kHz。开关闭合时,触点接触后并非立即稳定,而是要弹跳数次后才趋于稳定,此现象增加了开关从闭合到稳定的时间。驱动电压为50,60 V时开关的弹跳时间分别为174.94,66.84μs,由此可见,通过适当增加电压可有效降低开关时间和由闭合到稳定的时间。     

CAD/CAE系统中静电性能和机电性能仿真

在常规机械中很少考虑的微小静电力会对MEMS的电路产生一定影响,同时MEMS的元件在静电力作用下会发生变形,进而使得MEMS的几何结构和电容等产生变化,加之目前MEMS试制成本较高,因此,必须对整个系统的静电性能和机电性能进行分析.利用边界元素法,对MEMS各元件进行静电性能分析;采用有限元分析软件包对MEMS作机电性能分析,探讨了驱动电压与位移的关系、位移变化与电容的关系等.通过仿真测试发现,可提高设计质量,降低成本,缩短研制周期.     

一种超宽带MEMS开关的研制

MEMS射频器件,特别是超宽带器件,对其中的射频器件提出了宽带指标的要求。以此为背景,在理论分析的基础上设计了一种应用于12.5 GHz~50 GHz频带的超宽带双膜桥式MEMS开关,该开关具备低损耗、高隔离度等特点,文中给出了开关的制备工艺,并进行流水完成了芯片制备。经测试,该开关在设计频段内,回波损耗优于20 dB,插入损耗典型值0.3 dB@12.5~35 GHz,优于0.5 dB@45 GHz,隔离度全频段优于20 dB,驱动电压在45 V~55 V之间。     

高压断路器开关电容网络电机操动机构控制系统研究

高压断路器电机操动机构响应时间对电力系统的安全性能起到了至关重要的作用.为了降低电机操动机构的响应时间,提高分合闸速度,本文针对高压真空断路器电机操动机构控制装置设计了一套满足断路器动作要求的开关电容网络.通过改变电容器组串并联的方式满足断路器分闸或合闸过程中对电压等级的要求,并添加了驱动电机转角位置反馈和电压反馈,使...     

A novel DMTL capacitive switch with electrostatic actuation MAM capacitors

A novel DMTL capacitive switch with electrostatic actuation metal–air–metal (MAM) capacitors is presented. The top board of MAM capacitors will be pulled down together with the switch bridge. It has higher isolation in down-state than DMTL capacitive switch and has lower insert loss and higher self-actuation RF power comparing with MEMS shunt capacitive switch. Two of the novel DMTL capacitive switches are designed for high isolation and high self-actuation RF power, respectively. The calculated result shows that both of the two novel switches have lower insert loss than the MEMS shunt capacitive switch. The self-actuation RF power of them are 4 and 2.4 times that of MEMS shunt capacitive switch, respectively, at the cost of ?6.23 and ?3.54?dB reduction in isolation (30?GHz).     

Design and consideration of wafer level micropackaging for distributed RF MEMS phase shifters

A novel packaging structure which is performed using wafer level micropackaging on the thin silicon substrate as the distributed RF MEMS phase shifters wafer with vertical feedthrough is presented. The influences of proposed structure on RF performances of distributed RF MEMS phase shifters are investigated using microwave studio (CST). Simulation results show that the insertion loss (S₂₁) and return loss (S₁₁) of packaged MEMS phase shifters are −0.4–1.84 dB and under −10 dB at 1–50 GHz, respectively. Especially, the phase shifts have well linear relation at the range 1–48 GHz. At the same time, this indicated that the proposed pacakaging structure for the RF MEMS phase shifter can provide the maximum amount of linear phase shift with the minimum amount of insertion loss and return loss of less than −10 dB.     

折叠梁平面角对电容式RFMEMS开关性能的影响

低驱动电压电容式RFMEMS开关采用弹性拆叠梁支撑可变电容活动极板,使开关弹性结构具有很小的弹性系数,但也降低了开关的一阶模态谐振频率,致使开关无法获得较高的开关速度。提出了通过调整弹性折叠梁平面角微调弹性结构弹性系数的方法,在保证开关具有低驱动电压的同时,尽可能提高弹性结构的一阶模态谐振频率。仅改变弹性折叠梁平面角的大小,对其分别为0°,45°,90°的具体开关结构,应用MEMSCAD软件CoventorWare进行机电耦合仿真,定性分析了弹性折叠梁平面角对微结构弹性系数的影响。仿真结果表明：改变弹性折叠梁平面角大小,可以微调电容式RFMEMS开关的驱动电压和一阶模态谐振频率。     

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].     

Design and simulation of a thermally actuated MEMS switch for microwave circuits

The design, modeling, and optimization of a novel, thermally actuated CMOS‐MEMS switch are presented in this article. This series capacitive MEMS switch solves the substrate loss and down‐state capacitance degradation problems commonly plaguing MEMS switches. The switch uses finger structure for capacitive coupling. The vertical bending characteristic of bimorph cantilever beams under different temperatures is utilized to turn the switch on and off. A set of electrical, mechanical, and thermal models is established, and cross‐domain electro‐thermo‐mechanical simulations are performed to optimize the design parameters of the switch. The fabrication of the switch is completely CMOS‐process compatible. The design is fabricated using the AMI 0.6 μm CMOS process and a maskless reactive‐ion etching process. The measured results show the insertion loss and isolation are 1.67 and 33 dB, respectively, at 5.4 GHz, and 0.36 and 23 dB at 10 GHz. The actuation voltage is 25 V and the power consumption is 480 mW. This switch has a vast number of applications in the RF/microwave field, such as configurable voltage control oscillators, filters, and configurable matching networks. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Reliability design of thermally actuated MEMS switches based on V-shape beams

This paper presents the design and fabrication of the thermally actuated MEMS switches based on out-of-plane V-beams. The purpose of this research is to analyze the mechanical response of a V-thermal actuator fabricated from aluminum in order to improve the accuracy in response and to increase the switch lifetime. The actuation of this kind of switches is based on the thermal displacement of the mobile electrode under thermal load that is generated when the actuation voltage is applied. It can be used either as a capacitive switch or as a metal-to-metal one. The displacement of the mobile electrode for a given temperature is analytically calculated and validated both numerically and experimentally. Experimental investigations are performed on a macro-scale sample using a 3D digital image correlation measuring system, a heating source and a thermal camera for temperature monitoring. The first fabrication steps of the MEMS switch based on the V-beam thermal actuator are presented. The out-of-plane V-beams thermal MEMS switches can be monolithically integrated in RF applications.

     

RF MEMS packaged switch evaluation tests up to 25 GHz

This article presents the results of the series of experimental tests of a packaged RF MEMS switch manufactured as a chip on a silicon substrate in the Center for Materials and Microsystems of Fondazione Bruno Kessler. Experiments have been performed up to 25 GHz and included S-parameters check in different operation and environmental conditions, including variation of input power, ambient temperature and number of switching cycles. Presented RF MEMS SPST switch is a basic element of more complex reconfigurable networks such as SPxT switches, phase shifters, power attenuators etc.

     

A low loss and power efficient micro-electro-thermally actuated RF MEMS switch for low power and low loss applications

Microsystem Technologies - A novel laterally and micro-electro-thermally actuated RF MEMS switch is presented in this paper. Despite many RF MEMS switches requiring continuous actuation voltage to...     

A new design of multi-bit RF MEMS distributed phase shifters for phase error reduction

In this paper, the major source of phase error for multi-bit MEMS distributed phase shifters, the mismatch between adjacent bits, is investigated. A quantitative account of the phase deviation with the effect of mismatch considered is presented by the simulated results as well as theoretically calculated results. A novel multi-bit distributed MEMS phase shifter aimed to eliminate this error source is proposed. The basic concept for the structure is that, by controlling the phase shifter from the unit cell level, performance deterioration resulted from multiple reflection of the signal in the device in the phase state switching process is avoided. To verify the feasibility of the proposed structure, two X-band 5-bit distributed phase shifters are designed and simulated. Compared with the traditional structure, the average phase errors in all phase states of the two are improved by 28.22 and 36.52 % at 10 GHz. The average RMS phase errors in the bandwidth of 1–12-GHz of 56 frequency points are 1.23° and 1.85°. The improvements of the return loss and insertion loss are also exhibited. Furthermore, the aperiodic distributed phase shifter using different unit cells is introduced to demonstrate that the proposed structure can also be used to decrease the number of MEMS switches of multi-bit MEMS distributed phase shifters.     

Design and modeling of a novel RF MEMS series switch with low actuation voltage

This paper presents the design, analysis, modeling and simulation of a novel RF MEMS series switches with low actuation voltage. A mechanical modeling is presented to describe the behavior of the series switch. The switch is designed with special mechanical structures. The novel mechanical and mathematical modeling of the switch leads to calculation of the accurate actuation voltage. The spring constant has been calculated in relation to the presence of the residual stress in the beam. The calculated spring constant for this beam is used to determine the accurate actuation voltage. The size of the switch is 60 × 110 µm². The designed RF MEMS series switch was simulated using Intellisuite MEMS tool. He calculated actuation voltage is 4.05 V and simulated one is 4.2 V for 0.6 µm beam thickness. The calculated result is also very close with simulated one. The proposed switch compared with other electrostatic switches has low actuation voltage and small size. The RF characteristics were simulated using HFSS software and the switch has good RF performance. The insertion loss of 0.067 dB, return loss of 26 dB and isolation of 16 dB were achieved at 40 GHz.