一种L~U波段RF MEMS单刀十掷开关的设计

论文提出了一种适用于1GHz~60GHz频段的RF MEMS单刀十掷开关。该开关采用三角形上电极结构,以减小悬臂梁等效弹性系数和闭合接触面积,达到低驱动电压、高隔离度的目的。通过渐进传输线结构,改善阶跃补偿引起的信号损耗问题。仿真结果显示:该单刀十掷开关的驱动电压为13V,在1GHz~60GHz频段范围内,输入端两侧输出端口的插入损耗<2dB,其余八个端口插入损耗≤0.59dB,所有端口隔离度均>30dB。此开关可适用于无线通信系统、雷达系统和仪器测量系统等对射频性能要求高的领域内。

Design and fabrication of a series contact RF MEMS switch with a novel top electrode

Radio-frequency(RF)micro-electro-mechanical-system(MEMS)switches are widely used in communication devices and test instruments.In this paper,we demonstrate the structural design and optimization of a novel RF MEMS switch with a straight top electrode.The insertion loss,isolation,actuator voltage,and stress distribution of the switch are optimized and explored simultaneously by HFSS and COMSOL software,taking into account both its RF and mechanical properties.Based on the optimized results,a switch was fabricated by a micromachining process compatible with conventional IC processes.The RF performance in the DC to 18 GHz range was measured with a vector network analyzer,showing isolation of more than 21.28 dB over the entire operating frequency range.Moreover,the required actuation voltage was about 9.9 V,and the switching time was approximately 33μs.A maximum lifetime of 109 switching cycles was obtained.Additionally,the dimension of the sample is 1.8 mm×1.8 mm×0.3 mm,which might find application in the current stage.

DC—20GHz RF MEMS Switch

The design and fabrication of a RF MEMS switch is reported for the first time in China.The switching element consists of a thin metallic membrane,which has the metal-isolator-metal contact and a capacitive shunt switch as single-pole single-throw.When an electrostatic potential is applied to the membrane and the bottom electrode,the attractive electrostatic force pulls the metal membrane down onto the bottom dielectric.The switch characteristics,such as insertion loss and isolation,depend on the off and on-capacitance.The test results are as follows:the pulldown voltage is about 20V;the insertion loss is less than 0 69dB from DC to 20GHz in the up-state;the isolation is more than 13dB from 14 to 18GHz and 16dB from 18 to 20GHz in the down-state.

Thermal Effects and RF Power Handling of DC～5GHz MEMS Switch

A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gold platinum contact is used to get a stable and little insert loss.From DC to 5GHz,0 6dB insertion loss,30dB isolation,and 30μs delay are demonstrated.Thermal effect of the switch is tested in 85℃ and -55℃ atmosphere separately.From DC to 4GHz,the insert loss of the switch increases 0 2dB in 85℃ and 0 4dB in -55℃,while the isolation holds the same value as that in room temperature.To measure the power handling capability of the switch,we applied a continuous RF power increasing from 10dBm to 35 1dBm with the step of 1 0dBm across the switch at 4GHz.The switch keeps working and shows a decrease of the insert loss for 0 1～0 6dB.The maximum continuous power handling (35 1dBm,about 3 24W) is higer than the reported value of shunt switch (about 420mW),which implies series switches have much better power handling capability.

一种X波段三叉H型低电压RF MEMS开关设计

针对射频电路系统所需要的低电压,高隔离度,低插入损耗的应用需求,通过对开关正对面积对驱动电压产生的影响进行探究,设计了一款应用于X波段三叉H型的RF MEMS开关。开关具有六条悬臂梁作为支撑,通过增大上极板面积来降低开关的开启电压。分别使用HFSS和COMSOL对开关的射频性能和机械性能进行仿真,开关最终优化后,在8-12 GHz内,插入损耗为0.26~0.57 dB,隔离度大于31.30 dB。在10.1 GHz达到最优值,插入损耗为0.40 dB,隔离度为50.25 dB。开关电压在11V时就能够实现状态转换,开关的响应时间为18μs。此开关可与射频可重构器件结合,应用于新一代射频微波领域。

Capacitive Microwave MEMS Switch

A novel capacitive microwave MEMS switch with a silicon/metal/dielectric as a membrane is fabricated successfully by bonding and etching-stop process. Its principal, design, and fabricating process are described in detail. A patterned dielectric layer, Ta2O5, with dielectric constant of 24 is reached. Experiment results show this novel structure,where the switch＇s dielectric layer is not prepared on the transmission line, features very low insertion loss. The insertion loss is 0.06dB at 2GHz and lower than 0.5dB in the wider range from De up to 20GHz,especially when the transmission line metal is only 0. 5μm thick.

RF MEMS Switch on Poly-Silicon Substrate

The improvements of the design and the compatibility with silicon IC of RF MEMS switch are presented.The compatibility with silicon IC is realized by dielectric isolation technology,and the decrease of the pull voltage of the switch is done by etching some holes on the metal membrane.The preliminary test results are as follows: C off and C on are 0 32pF,6pF,respectively;the pull down voltage is about 25V.The package of the RF MEMS switch is done by micro stripline,and the isolation and the insertion loss are 35dB,2dB,respectively at 1 5GHz;the switching speed is about 3μs by oscilloscope.

Effect of Inertial Shock on RF MEMS Capacitive Switches Property in Low Vacuum

The influence of outside inertial shock combined with RF signal voltages on the properties of a shunt capacitive MEMS switch encapsulated in a low vacuum environment is analyzed considering the damping of the air around the MEMS switch membrane. An analytical expression that approximately computes the displacement induced by outside shock is obtained. According to the expression, the minimum required mechanical stiffness constant of an MEMS switch beam in some maximum tolerated insertion loss condition and some external inertial shock environment or the insertion loss induced by external inertial shock can also be obtained. The influence is also illustrated with an RF MEMS capacitive switch example,which shows that outside environment factors have to be taken into account when designing RF MEMS capacitive switches working in low vacuum. While encapsulating RF MEMS switches in low vacuum diminishes the air damping and improves the switch speed and operation voltage,the performances of a switch is incident to being influenced by outside environment. This study is very useful for the optimized design of RF MEMS capacitive switches working in low vacuum.

射频MEMS开关寿命测试系统的设计与实现

针对射频MEMS开关寿命测试成本昂贵,测试连线复杂,且随着射频MEMS开关的尺寸不断缩小,传统测试效率低、测试任务只能在实验室进行等问题,本文设计并实现了一种小型且集成化的射频MEMS开关测试系统,组建了具备信号发生、波形实时监测、寿命计算、数据记录和测试报告打印等功能的射频MEMS开关测试系统,并用该系统对某款射频MEMS开关进行了初步测试评价。结果表明该系统较好的完成了射频MEMS开关的开关电压、开关时间和冷、热寿命的测试,能够满足射频MEMS开关的测试要求,证明了该测试系统的实用性和测试工作的准确性。

一种晶圆级封装的MEMS数控衰减器

设计实现了一种晶圆级封装的三位MEMS数控衰减器,工作频段DC~15 GHz,衰减范围0~35 dB,步进5 dB。衰减器采用MEMS工艺实现,信号传输采用共面波导(CPW)结构,6个直接接触式悬臂梁MEMS开关对称放置实现不同衰减量的切换,每个开关带有三个触点,电阻网络采用T型结构,整个衰减器实现晶圆级封装。测试结果显示,DC~15 GHz频段内实现了8个衰减态,衰减器插入损耗小于1.7 dB,回波损耗小于-15 dB,衰减平坦度小于±5%,功耗几乎为零。芯片尺寸为2.7 mm×2.7 mm×0.8 mm。

高速MEMS开关长时间实时监测系统设计

为了监测射频MEMS开关的工作状态,设计了一种基于FPGA复原波形计数技术的长时间工作状态监测系统。该系统由驱动和检测两部分构成:对于驱动电压比较高的MEMS芯片设计了可调的高压驱动电路,电压可调范围在40_(Vpp)~110_(Vpp)之间连续变化;通过高压驱动控制射频MEMS器件的通断,将通过的射频信号调理采集并通过阈值判定开关通断的有效性。该系统达到了实时监测射频MEMS开关工作状态的目的,另一方面,在长时间连续工作条件下,监测系统的计数功能可实现对开关寿命的测试。

一种L~Ka波段的双边多触点型RF MEMS单刀六掷开关

目前通讯、导航等领域对单刀多掷开关有广泛的需求,而此类开关存在体积大、工作频带窄、插入损耗大、隔离度低等问题。文章设计了一种串联接触式双边多触点型RF MEMS单刀六掷开关。开关的下电极上设有三个圆形触点,远端连接有喇叭状过渡带,其上是带有带状孔的“X”形上电极,通过减小接触电阻和耦合电容来改善射频性能。经HFSS软件仿真优化,该开关工作频率可覆盖L~Ka波段,且在26.5 GHz下,插入损耗≤0.3 dB,隔离度≥37 dB,性能良好,尺寸为1.05×1.05×0.5 mm^(3)。结果表明,设计的单刀六掷开关射频性能具有较大优势,同时满足小型化的要求,因此在L~Ka波段的导航、认知无线网络以及微波测试等领域具有较大的应用前景。

一种L~E波段的混合型射频MEMS单刀双掷开关设计

针对传统RF MEMS单刀双掷(SPDT)开关应用存在频段低、插入损耗高、隔离度低等问题,设计了一种混合型SPDT开关,通过在一条通路上设置接触式开关和电容式开关,实现了在L~E频段下的低插入损耗和高隔离度。通过设计蛇形上电极结构,降低了上电极的弹性系数,进而降低开关上电极下拉所需的驱动电压。采用HFSS仿真软件对混合型SPDT开关的射频性能参数进行了优化,并利用COMSOL对开关的蛇形上电极进行应力-位移分析。仿真结果表明,在DC~90 GHz的频段下,SPDT开关的插入损耗小于1.5 dB@90 GHz,隔离度大于52 dB@67 GHz、29 dB@90 GHz。此开关适用于无线通信系统、雷达系统和仪器测量系统等对工作频段要求高的领域内。

减少静电漂移的高可靠RF MEMS开关研究

RF MEMS开关具有制作工艺简单、易于集成等优点。而目前由电介质膜电荷积累造成的静电漂移及频繁机械碰撞导致严重的可靠性问题阻碍了其嵌入终端射频系统稳定性的提高。因此结构上采用电介质悬空薄膜改善电荷积累问题,并对开关机械结构限位实现开关的动态缓冲,降低高频次的机械碰撞损伤。同时依靠凸台触点结构,减少静电漂移。确立了电介质膜充电、开关寿命的理论模型并预测开关的寿命。结果表明,所设计开关寿命超过12900 h。相比已有RF MEMS开关,在两极板间距及金属梁-电介质膜间距分别相等的情况下,所提出的开关结构,寿命分别提高253倍和166倍,极大地改善静电漂移问题。在52.2 GHz工作频率下,隔离度为-41.31 dB,损耗为-0.25 dB,响应时间为50μs,为高性能、高可靠、长寿命射频开关提供了理论模型。

一种基于光刻胶牺牲层的RF MEMS开关制备方法

论文针对RF MEMS开关上电极传统的牺牲层工艺存在工艺兼容性差、释放时热应力大等问题,提出了一种基于光刻胶牺牲层的MEMS开关制备方法。通过采用在氮气环境下进行固化处理的方法,解决了光刻胶作为牺牲层时容易出现的表面褶皱、破裂等问题,同时提高了牺牲层表面的平整度;通过氧等离子体干法刻蚀释放工艺,获得了具有高平整度和低粗糙度的MEMS开关上电极结构。测试结果表明,基于光刻胶牺牲层工艺制备的RF MEMS开关在DC-20GHz频段内性能良好,隔离度均小于-30.0dB,插入损耗均大于-1.0dB。该RF MEMS开关具有良好的应用前景。

一种高功率射频MEMS开关设计

随着无线通信设备小型化以及宽通信范围的需求导致器件的功率密度要求越来越高。射频前端接收器和基站天线等射频通信应用要求开关能处理1W~2W的射频信号。论文设计了一种低损耗、高功率容量的四触点射频MEMS开关。文中对四触点射频MEMS开关基地材料和上电极结构进行优化,提升了四触点射频MEMS开关的射频性能和功率容量。经HFSS电磁仿真可知:该射频MEMS开关在L~K波段内,插入损耗≤0.2GHz,隔离度≥27dB,经理论计算,该射频MEMS开关的功率容量为2.17W。

K波段可调功率分配比的MEMS五端口环形结研究

提出了一种基于MEMS悬臂梁开关的五端口环形结的结构,以实现可调谐的功率分配比。在结构上,采用MEMS悬臂梁开关控制环形结信号线是否接地短路,进而控制整体电路的拓扑结构,达到输出端口的功率分配比可调的效果。建立了五端口环形结等效电路的S参数微波系统模型,并通过理论模型与仿真结果相比较,验证了模型的正确性。利用该模型可知,对于四分之一波长时,在UP态,端口1的微波信号功率被等分至端口2和端口4,端口3和端口5近乎无输出;在DOWN态,端口1的微波信号功率被分至端口2、端口3、端口4和端口5输出,其中端口2和端口4的输出功率相等,而端口3和端口5的输出功率为端口2或端口4的一半。经过有限元软件验证,在K波段中心频率22 GHz附近,UP态时S_(11),S_(31),S_(51)均小于-20 dB,S_(21),S_(41)均大于-3.3 dB;DOWN态时S_(11)小于-17 dB,S_(21)-S_(31)和S_(41)-S_(51)均接近3 dB,验证了设计的有效性。

A novel multifunctional electronic calibration kit integrated by MEMS SPDT switches

Design and simulation results of a novel multifunctional electronic calibration kit based on microelectromechanical system(MEMS)single-pole double-throw(SPDT)switches are presented in this paper.The short-open-load-through(SOLT)calibration states can be completed simultaneously by using the MEMS electronic calibration,and the electronic calibrator can be reused 10^(6) times.The simulation results show that this novel electronic calibration can be used in a frequency range of 0.1 GHz–20 GHz,the return loss is less than 0.18 dB and 0.035 dB in short-circuit and open-circuit states,respectively,and the insertion loss in through(thru)state is less than 0.27 dB.On the other hand,the size of this novel calibration kit is only 6 mm×2.8 mm×0.8 mm.Our results demonstrate that the calibrator with integrated radiofrequency microelectromechanical system(RF MEMS)switches can not only provide reduced size,loss,and calibration cost compared with traditional calibration kit but also improves the calibration accuracy and efficiency.It has great potential applications in millimeter-wave measurement and testing technologies,such as device testing,vector network analyzers,and RF probe stations.

Sensitivity analysis of pull-in voltage for RF MEMS switch based on modified couple stress theory

An approximate analytical model for calculating the pull-in voltage of a stepped cantilever-type radio frequency （RF） micro electro-mechanical system （MEMS） switch is developed based on the Euler-Bernoulli beam and a modified couple stress theory, and is validated by comparison with the finite element results. The sensitivity functions of the pull-in voltage to the designed parameters are derived based on the proposed model. The sensitivity investigation shows that the pull-in voltage sensitivities increase/decrease nonlinearly with the increases in the designed parameters. For the stepped cantilever beam, there exists a nonzero optimal dimensionless length ratio, where the pull-in voltage is insensitive. The optimal value of the dimensionless length ratio only depends on the dimensionless width ratio, and can be obtained by solving a nonlinear equation. The determination of the designed parameters is discussed, and some recommendations are made for the RF MEMS switch optimization.

A novel low-loss four-bit bandpass filter using RF MEMS switches

This paper details the design and simulation of a novel low-loss four-bit reconfigurable bandpass filter that integrates microelectromechanical system(MEMS)switches and comb resonators.A T-shaped reconfigurable resonator is reconfigured in a'one resonator,multiple MEMS switches'configuration and used to gate the load capacitances of comb resonators so that a multiple-frequency filtering function is realized within the 7-16 GHz frequency range.In addition,the insertion loss of the filter is less than 1.99 dB,the out-of-band rejection is more than 18.30 dB,and the group delay is less than 0.25 ns.On the other hand,the size of this novel filter is only 4.4 mm×2.5 mm×0.4 mm.Our results indicate that this MEMS reconfigurable filter,which can switch 16 central frequency bands through eight switches,achieves a low insertion loss compared to those of traditional MEMS filters.In addition,the advantages of small size are obtained while achieving high integration.