硅基共面波导RF MEMS开关设计关键技术研究

发布时间：2018-12-11 02:37

【摘要】：射频微机电系统(RF MEMS)技术作为未来通信的核心技术,通过灵巧的设计,可以实现更复杂的功能,还具有更轻便、低能耗、低成本等特点。RF MEMS开关由于其高隔离、低损耗、小体积、易集成、优良线性度等特性,近年来成为国内外研究热点。完善开关设计,将其应用于可调射频器件如可调滤波器、可重构天线、移相器等已经成为研究的趋势。基于MEMS技术的射频开关和基于开关的可调射频器件在卫星、通信系统、各类雷达系统、新概念探测设备等领域具有巨大的应用前景。本文面向硅基共面波导(CPW) RF MEMS开关,从需求出发,针对其电磁,电路和力学特性进行建模分析。通过对上、下态电容,电感和电阻的计算分析,实现了开关电磁参数的精确提取；建立了开关的电路模型,进行了电路模型中电参数射频性能分析；分析计算了开关弹性系数,建立了静电驱动下的静态和动态变形分析,并对低驱动电压设计方法进行了研究。在对模型分析的基础上,分析了影响开关射频性能的因素,引入了共面波导缺陷地(DGS)结构,有效地降低了开关的谐振频率。完成了低驱动电压开关、高隔离度开关、高可靠性开关、稳定电感直插式开关的设计、仿真及测试,并将其应用于模拟可调和数字可调滤波器设计中,验证了开关设计的有效性。设计完成了两套开关平坦化MEMS加工方案,对开关和可调滤波器进行了加工测试,分析了测试结果,验证了理论模型,给出了工艺改进方案。主要创新点如下： 1.提出了一种开关电容精确计算方法提出了一种求解MEMS开关上态电容的方法,将带有MEMS桥的共面波导等效成两组微带线,通过精确计算微带线电容,实现RF MEMS开关上态电容的精确提取。其准确性在参数提取后的有限元结构仿真和电路模型仿真对比中得到了验证。 2.构建了一种基于缺陷地结构的电感可调开关模型在开关电磁模型分析的基础上,提出将共面波导传输线的缺陷地结构引入硅基共面波导MEMS开关设计中。根据电磁参数的提取,验证了缺陷地额外电感的引入。在不改变开关尺寸的前提下,该结构增加了开关的设计维度,为电容式开关谐振频率的低频化设计提供了一种有效的解决方案。通过开关的设计、仿真及测试验证了其有效性。 3.提出了一种电容式MEMS开关射频性能优化设计方法研究了开关梁几何尺寸和梁上释放孔对射频性能隔离度和插入损耗的影响,分析了影响电容式开关谐振频率的因素,包括极板相对面积、介质层间距和介电常数、梁结构本身电感和缺陷地引入电感对谐振频率的影响,提出了一种开关射频性能优化设计的方法。 4.研制了多款高性能MEMS开关根据对开关性能需求的不同,设计了两款低驱动电压开关,包括圆弧弯曲梁开关和双弯曲梁开关,开关在保证隔离度的同时驱动电压测试低于30V；两款高隔离度电压开关,包括糖果形开关和混合式开关,在工作频率范围内隔离度优于-40dB；两款高可靠性开关,包括仿生物神经细胞结构的仿生式和四通式开关；多款稳定电感的直插式开关,避免了开关梁电感对谐振频率的影响,便于电感的准确设计。开关谐振频率设计包括Ku至Ka波段。通过理论模型分析提取了其特性参数,并将其加工测试。 5.实现了基于MEMS开关的模拟、数字可调滤波器一体化设计在对开关设计和参数提取的基础上,对开关、滤波器进行一体化设计,将设计的新型低驱动电压圆弧弯曲梁开关应用于滤波器设计,完成了基于K倒相器的模拟可调滤波器和槽线半波耦合数字可调滤波器设计。进行了可调滤波器的加工,开关驱动电压低于30V,模拟可调频率范围为20.26GHz至26.15GHz,数字可调频率为19.2GHz,19.9GHz,20.5GHz,21.7GHz。测试验证了基于开关的可调滤波器一体化设计的有效性。 6.设计了MEMS开关平坦化工艺提出了采用多次涂胶干法刻蚀结合胶体自流平效应的开关表面平坦化加工工艺,加工粗糙度低于100A。完成了金梁和铝梁开关结构的加工、测试和分析。分析了测试结果,验证了影响开关谐振频率漂移的因素,在对开关失效分析的基础上提出了工艺改进方案。论文最后对研究工作进行了总结,给出了进一步研究的方向。
[Abstract]:The radio-frequency micro-electro-mechanical system (RF MEMS) technology, as the core technology of future communication, can realize more complex functions through the smart design, and also has the characteristics of light weight, low energy consumption, low cost and the like. The RF MEMS switch has become a hot spot at home and abroad due to its high isolation, low loss, small volume, easy integration and excellent linearity. The design of the switch is improved, and it can be applied to adjustable RF devices such as tunable filter, reconfigurable antenna, phase shifter and so on. The radio-frequency switch based on the MEMS technology and the adjustable radio-frequency device based on the switch have great application prospect in the fields of satellite, communication system, various radar systems, new concept detection equipment and the like. In this paper, a silicon-based coplanar waveguide (CPW) RF MEMS switch is used to model the electromagnetic, electrical and mechanical properties of a silicon-based coplanar waveguide (CPW) RF MEMS switch. Through the calculation and analysis of the capacitance, the inductance and the resistance of the upper and lower states, the accurate extraction of the electromagnetic parameters of the switch is realized, the circuit model of the switch is established, the radio frequency performance of the electrical parameters in the circuit model is analyzed, and the elastic system of the switch is calculated and calculated. The static and dynamic deformation analysis under the electrostatic drive is established, and the design method of the low-drive voltage is studied. Based on the analysis of the model, the factors affecting the radio frequency performance of the switch are analyzed, the defect of the coplanar waveguide (DGS) is introduced, and the resonance frequency of the switch is effectively reduced. The design, simulation and test of low-drive voltage switch, high-isolation switch, high-reliability switch and stable inductance-plug-in switch are completed, and it is applied to the design of the analog and harmonic digital adjustable filter, and the effective design of the switch is verified. In this paper, two sets of switch-flattening MEMS processing schemes are designed, the switch and the adjustable filter are processed and tested, the test results are analyzed, the theoretical model is verified, and the process improvement party is given. Case. Key innovations The point is as follows: 1. A switching capacitor is proposed In this paper, a method for solving the state capacitance of a MEMS switch is proposed, and the coplanar waveguide with the MEMS bridge is equivalent to two sets of microstrip lines, Calculate the capacitance of the microstrip line and realize the on-state of the RF MEMS switch The accurate extraction of the capacitance. The accuracy of the method is the simulation of the finite element structure and the simulation of the circuit model after the parameter extraction the comparison was verified. 2. A defect-based junction was built On the basis of the analysis of the electromagnetic model of the switch, the structure of the inductance-adjustable switch model is put forward to introduce the defect structure of the coplanar waveguide transmission line into the silicon-based coplanar waveguide. The design of the waveguide MEMS switch. Based on the extraction and verification of the electromagnetic parameters, Under the premise of not changing the size of the switch, the design dimension of the switch is increased, and the low-frequency design of the resonant frequency of the capacitive switch is provided. for an efficient solution. The switch is designed, simulated, True and the test verified its validity. 3. A capacitive ME is proposed The influence of the size of the switch beam and the release hole on the isolation and insertion loss of the RF performance is studied in the design of the radio frequency performance of the MS switch, and the influence of the capacitance type switch is analyzed. The factors of the vibration frequency include the relative area of the plate, the distance and the dielectric constant of the dielectric layer, the inductance of the beam structure and the effect of the induced inductance on the resonant frequency. The invention relates to a method for optimizing and designing a radio frequency performance of a switch. 4. A variety of high-performance MEMS switches are developed, which are designed with two low-drive voltage switches based on the different performance requirements of the switch, including the arc-bending beam switch and the double-bending beam switch, and the switch can drive the electric motor at the same time as the isolation degree is guaranteed. The voltage test is less than 30V; the two high-isolation voltage switches, including the candy-shaped switch and the hybrid switch, have a better isolation over-40dB in the operating frequency range; the two high-reliability switches, including the bionic type of the bionic nerve cell structure and the switch beam is avoided. the effect of the inductance on the resonance frequency is convenient for the accurate setting of the inductance, The switch resonant frequency is designed to include Ku to Ka band. The characteristic parameters are extracted by the type analysis, and the processing test is carried out. The simulation of the MEMS switch and the integrated design of the digital adjustable filter are based on the design of the switch and the parameter extraction, and the switch and the filter are integrated and designed, and the design The novel low-drive-voltage circular-arc beam switch is applied to the design of the filter, and the K-phase inverter is completed. The tunable filter and the slot line half-wave coupled digital adjustable filter are designed. The adjustable filter is processed, the driving voltage of the switch is lower than 30V, the range of the analog adjustable frequency is 20. 26GHz to 265.15GHz, and the digital adjustable frequency is 19.2GHz. 19.9GHz, 20.5GHz, 21.7GHz. The test is based on the switch-based adjustable filter. The effectiveness of the design is as follows: 6. The planarization process of MEMS switch is designed The surface of the switching surface of the flat effect is flat and the processing roughness is low. The processing, testing and analysis of the switch structure of the gold beam and the aluminum beam are completed in 100A. The results of the test are analyzed and the resonant frequency of the influence switch is verified. The factors of drift have been put forward on the basis of the analysis of the failure of the switch.
【学位授予单位】：北京邮电大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM564

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