适用于编码超材料的低启动电压高隔离MEMS射频开关  

Low turn-on voltage and high isolation RF MEMS switches for coding metamaterial

作　　者：林铭团 陈柏池 龙世新 袁博秋 郭志清 丁浩 查淞 吴学忠[1] LIN MingTuan;CHEN BaiChi;LONG ShiXin;YUAN BoQiu;GUO ZhiQing;DING Hao;ZHA Song;WU XueZhong(College of Intelligence Science and Technology,National University of Defense Technology,Changsha 410073,China;College of Electronic Science,National University of Defense Technology,Changsha 410073,China;School of Physics and Electronic Science,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]国防科技大学智能科学学院,长沙410073 [2]国防科技大学电子科学学院,长沙410073 [3]长沙理工大学物理与电子科学学院,长沙410114

出　　处：《中国科学：技术科学》2023年第8期1411-1418,共8页Scientia Sinica(Technologica)

基　　金：博士后创新人才支持计划项目(编号:BX2021368)资助。

摘　　要：电磁编码超材料利用可调控器件如二极管、微机电(micro-electro-mechanical system,MEMS)开关、液晶材料等可实现对空间电磁波的操控,在智能通信、雷达、无线电能传输等方面具有重要的应用价值.然而,目前主流的PIN(positive-intrinsic-negative)二极管、MEMS开关等调控器件,存在寄生电容大、非线性效应严重、电压控制复杂等缺点,限制了电磁编码超材料的广泛应用.文中首先分析了单悬臂梁MEMS开关启动电压和端口隔离度的矛盾问题.进一步,提出了双悬臂梁MEMS射频开关设计,其由两个悬臂梁串联而成.通过减少悬臂梁与驱动电极的间隙距离,可将启动电压降低至5 V以兼容常用的TTL(transistor-transistor logic)输出电平,降低了电压控制电路的复杂度.由于采用双臂串联的方式,隔离度得以保证,在全频段内达到20 dB以上.所提MEMS开关的机电性能经过COMSOL软件仿真,验证了可行性.随后的电磁仿真结果表明,双悬臂梁MEMS结构在电极间隙为1.5μm时的隔离性能优于间隙为2.5μm的单悬梁臂MEMS开关.最后将所设计的MEMS开关应用于典型的能量选择线条型超材料结构.结果表明,通过控制MEMS开关闭合或断开,超材料结构呈现出了典型的透波和屏蔽两种状态,验证了所提MEMS开关应用于超材料结构的可行性.相比PIN二极管,所提的MEMS开关电磁性能更接近于理想开关.本文提出的MEMS设计可推动MEMS编码超材料的进一步推广和应用.Electromagnetic-coded metamaterials can modulate electromagnetic waves by using adjustable devices such as diodes,microelectromechanical systems(MEMS)switches,and liquid crystal materials,which have applications in intelligent communication,radar,and radio energy transmission.However,current devices such as positive-intrinsic-negative(PIN)diodes and MEMS switches have the disadvantages of large parasitic capacitance and nonlinear effect or complex voltage control circuits,which limit the widespread use of coding metamaterials.The contradiction between the turn-on voltage and single-cantilever MEMS switch isolation is first described.Furthermore,based on the traditional single-cantilever MEMS structure,a double-cantilever MEMS RF switch structure composed of two cantilevers in series is proposed.By reducing the distance between the cantilever and the driving electrode,the turn-on voltage can be reduced to 5 V.This voltage is compatible with the output level of the common control system and can reduce the external voltage control circuit.Simultaneously,isolation can be ensured based on the use of double cantilevers,reaching more than 20 dB for the whole band.The electromechanical performance of the proposed MEMS switch is also verified using COMSOL software simulation.Subsequently,electromagnetic simulation software helps simulate the electromagnetic characteristics of the switch.The simulation results show that the isolation performance of the double-cantilever MEMS structure with a gap of 2.5μm is better than that of the single-cantilever MEMS switch with an electrode gap of 1.5μm.Finally,the designed MEMS switch is applied to a typical energy-selective linear metamaterial structure.The results show that by controlling the MEMS switch to be connected or disconnected,the metamaterial structure presents two typical states,i.e.,transmission and shielding.The presence of these states verifies the feasibility of the proposed MEMS switch for the metamaterial structure.Compared with a PIN diode,the electromagnetic per

关 键 词：MEMS开关 低启动电压 高隔离度 编码超材料 

分 类 号：TM564[电气工程—电器] TB34[一般工业技术—材料科学与工程]