Multilayer Organic Multichip Module Implementing Hybrid Microelectromechanical Systems

We present the design and development of an organic package that is compatible with fully released RF microelectromechanical systems (MEMS). The multilayer organic package consists of a liquid-crystal polymer film to provide near hermetic cavities for MEMS. The stack is further built up using organic thin-film polyimide. To demonstrate the organic package, we have designed and implemented a 2-bit true-time delay X-band phase shifter using commercially available microelectromechanical switches. The packaged phase shifter has a measured insertion loss of 2.45 plusmn 0.12 dB/bit at 10 GHz. The worst case phase variation of the phase shifter at 10 GHz is measured to less than 5deg. We have also conducted temperature cycling (-65degC to 150degC) and 85/85 to qualify the packaging structures.     

Distributed 2- and 3-bit W-band MEMS phase shifters on glass substrates

This paper presents state-of-the-art RF microelectromechanical (MEMS) phase shifters at 75-110 GHz based on the distributed microelectromechanical transmission-line (DMTL) concept. A 3-bit DMTL phase shifter, fabricated on a glass substrate using MEMS switches and coplanar-waveguide lines, results in an average loss of 2.7 dB at 78 GHz (0.9 dB/bit). The measured figure-of-merit performance is 93/spl deg//dB-100/spl deg//dB (equivalent to 0.9 dB/bit) of loss at 75-110 GHz. The associated phase error is /spl plusmn/3/spl deg/ (rms phase error is 1.56/spl deg/) and the reflection loss is below -10 dB over all eight states. A 2-bit phase shifter is also demonstrated with comparable performance to the 3-bit design. It is seen that the phase shifter can be accurately modeled using a combination of full-wave electromagnetic and microwave circuit analysis, thereby making the design quite easy up to 110 GHz. These results represent the best phase-shifter performance to date using any technology at W-band frequencies. Careful analysis indicates that the 75-110-GHz figure-of-merit performance becomes 150/spl deg//dB-200/spl deg//dB, and the 3-bit average insertion loss improves to 1.8-2.1 dB if the phase shifter is fabricated on quartz substrates.     

基于微机电系统开关的四位移相器设计

为了解决相控阵雷达小型化和低损耗的问题,设计了一个工作频率为2.2 GHz的射频微机电系统(MEMS)四位开关线型移相器。首先分析了直接接触式MEMS串联开关的插入损耗和隔离度,并得到仿真结果。在此基础上设计了基于该开关的移相范围为0~180o的四位移相器电路,相移量为12o每步。采用HFSS软件对其进行仿真,得到移相精确度、插入损耗和隔离度等关键结果,移相器工作在2.2 GHz时,隔离度大于20 dB,插入损耗小于1 dB。该设计与传统移相器相比体积更小,且具有更小的插入损耗和更大的隔离度。     

基于SP4T开关的4位MEMS开关线式移相器设计

设计了一款4位MEMS开关线式移相器,由SP4TMEMS开关和微带传输线构成,工作于X波段。单刀四掷(single pole 4throw,SP4T)开关用于切换两条不同电长度的信号通道,即参考相位通道和延迟相位通道。每个SP4T开关包含4个悬臂梁接触式RF MEMS串联开关。介绍了4位MEMS开关线式移相器的总体设计,并给出了其关键部件SP4T开关和相位延迟线的设计细节。采用ADS软件仿真分析了器件的电气性能。仿真分析得到:SP4T开关在中心频率10GHz处的回波损耗为-36dB,插入损耗约为0.18dB;移相器各相位的回波损耗均低于-15dB,插入损耗为-0.8～-0.4dB。这种射频MEMS移相器具有小型化、低功耗和高隔离度的优点。     

开关线型四位数字MEMS移相器

介绍了一种基于射频微机械串联开关设计的开关线型四位数字微机电系统(M icro-e lectrom echan ica lSystem s以下简称M EM S)移相器。该移相器集成了16个RF M EM S开关,使用了13组四分之一波长传输线和M IM接地耦合电容,有效地使开关的驱动信号和微波信号隔离,串联容性开关设计有效地降低了开关的启动电压。使用低温表面微机械工艺在360μm厚的高阻硅衬底上制作移相器,芯片尺寸4.8 mm×7.8 mm。移相器样品在片测试结果表明,频点10.1 GH z,22.5°相移位的相移误差为±0.4,°插损2.8 dB;45°位的相移误差为±1.1,°插损2.0 dB;在X波段,对16个相移态的测试结果表明,移相器的插入损耗小于4.0 dB,驻波比小于2.4,开关驱动电压为17~20 V。     

A 2-bit miniature X-band MEMS phase shifter

The design and performance of a compact low-loss X-band true-time-delay (TTD) MEMS phase shifter fabricated on 8-mil GaAs substrate is described. A semi-lumped approach using microstrip transmission lines and metal-insulator-metal (MIM) capacitors is employed for the delay lines in order to both reduce circuit size as well as avoid the high insertion loss found in typical miniaturized designs. The 2-bit phase shifter achieved an average insertion loss of -0.70 dB at 9.45 GHz, and an associated phase accuracy of /spl plusmn/1.3/spl deg/. It occupies an area of only 5 mm/sup 2/, which is 44% the area of the smallest known X-band MEMS phase shifter . The phase shifter operates over 6-14 GHz with a return loss of better than -14 dB.     

A compact V-band 2-bit reflection-type MEMS phase shifter

Air-gap overlay CPW couplers and low-loss series metal-to-metal contact microelectromechanical system (MEMS) switches have been employed to reduce the loss of reflection-type MEMS phase shifters at V-band. Phase shift is obtained by changing the lengths of the open-ended stubs using series MEMS switches. A 2-bit [135] reflection-type MEMS phase shifter showed an average insertion loss of 4 dB with return loss better than 11.7 dB from 50 to 70 GHz. The chip is very compact with a chip size as small as 1.5 mm /spl times/ 2.1 mm.     

A Ku‐Band 5‐Bit Phase Shifter Using Compensation Resistors for Reducing the Insertion Loss Variation

This paper describes the performance of a Ku‐band 5‐bit monolithic phase shifter with metal semiconductor field effect transistor (MESFET) switches and the implementation of a ceramic packaged phase shifter for phase array antennas. Using compensation resistors reduced the insertion loss variation of the phase shifter. Measurement of the 5‐bit phase shifter with a monolithic microwave integrated circuit demonstrated a phase error of less than 7.5° root‐mean‐square (RMS) and an insertion loss variation of less than 0.9 dB RMS for 13 to 15 GHz. For all 32 states of the developed 5‐bit phase shifter, the insertion losses were 8.2 ± 1.4 dB, the input return losses were higher than 7.7 dB, and the output return losses were higher than 6.8 dB for 13 to 15 GHz. The chip size of the 5‐bit monolithic phase shifter with a digital circuit for controlling all five bits was 2.35 mm × 1.65 mm. The packaged phase shifter demonstrated a phase error of less than 11.3° RMS, measured insertion losses of 12.2 ± 2.2 dB, and an insertion loss variation of 1.0 dB RMS for 13 to 15 GHz. For all 32 states, the input return losses were higher than 5.0 dB and the output return losses were higher than 6.2 dB for 13 to 15 GHz. The size of the packaged phase shifter was 7.20 mm × 6.20 mm.     

The package integration of RF-MEMS switch and control IC for wireless applications

The integration of microelectromechanical systems (MEMS) switch and control integrated circuit (IC) in a single package was developed for use in next-generation portable wireless systems. This packaged radio-frequency (RF) MEMS switch exhibits an insertion loss under -0.4 dB, and isolation greater than -45 dB. This MEMS switch technology has significantly better RF characteristics than conventional PIN diodes or field effect transistor (FET) switches and consumes less power. The RF MEMS switch chip has been integrated with a high voltage charge pump plus control logic chips into a single package to accommodate the low voltage requirements in portable wireless applications. This paper discusses the package assembly process and critical parameters for integration of MEMS devices and bi-complementary metal oxide semiconductor (CMOS) control integrated circuit (IC) into a single package.     

Ka波段开关线型MEMS移相器的设计与研究

面向现代通信及相控阵雷达领域的需求,设计了一种移相间隔为22.5°的Ka波段4位开关线型射频MEMS移相器。主要对实现移相功能的四个移相单元进行了设计,采用台阶补偿技术优化移相单元上下通路分工选通,以提供最佳的阻抗匹配;采用直角转角结构,设计了可提高CPW直角性能的延迟线,并对应用该延迟线的4位开关线型移相器进行了总体设计。用HFSS进行建模仿真,结果表明,在0~40 GHz工作频段内,16个状态的插入损耗均小于2.15 dB,回波损耗均大于19.18 dB,驻波比均小于1.25,在40 GHz频点处的相移误差在1.57°以内,整体尺寸为10 mm²。     

交直流隔离的分布式MEMS移相器设计

设计了一种五位分布式微电子机械系统（MEMS）移相器,通过分析对比传统分布式MEMS移相器加载直流偏置的两种方式,提出了一种新的直流偏置的加载方式,能解决传统方式带来的交直流干扰和引线繁杂问题,同时工艺容易实现。采用ADS软件对移相器进行级联仿真,优化了微波性能参数,仿真得出移相器在35 GHz时移相精确度小于3°,移相器的插入损耗小于0.5 dB,回波损耗大于23 dB。给出了五位分布式MEMS移相器的工艺流程,同时验证了所设计加载直流偏置方式工艺简单的优势。     

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。     

一个DC-32GHz两位微机械移相器

采用分布式微机械传输线结构实现了两位移相器,并且为了减小传输线负载电容和驱动电压首次提出了用共面波导传输线来驱动微机械桥的结构(共面波导驱动结构).结果显示驱动电压小于20V,20GHz时两位移相器的相移为0°/20.1°/41.9°/68.2°,插入损耗为-1.2dB.在DC到32GHz的范围内相移具有良好的线性,插入损耗小于-1.8dB,反射损耗好于-11dB.实验结果表明了该结构在高介电常数衬底上制造低插损、宽带数字微机械射频移相器的潜力.     

X波段GaN五位数字移相器MMIC的设计

采用0.5μm GaN HEMT工艺设计了X波段五位数字移相器的单片微波集成电路(MMIC),描述了移相器的设计过程,并进行了版图电磁仿真。该移相器采用高低通滤波器型网络和加载线型结构。利用电路匹配技术设计移相器电路的开关结构,将GaN器件的插入损耗从14 dB降至1 dB。版图仿真结果表明,在9.2 GHz~10.2 GHz频带范围内,均方根移相误差小于3.5°,插入损耗典型值为17.4 dB,回波损耗小于-12 dB,版图尺寸为5.0 mm×4.7 mm。     

A Monolithic Phased Array Using 3-bit Distributed RF MEMS Phase Shifters

This paper presents a novel electronically scanning phased-array antenna with 128 switches monolithically implemented using RF microelectromechanical systems (MEMS) technology. The structure, which is designed at 15 GHz, consists of four linearly placed microstrip patch antennas, 3-bit distributed RF MEMS low-loss phase shifters, and a corporate feed network. MEMS switches and high-Q metal-air-metal capacitors are employed as loading elements in the phase shifter. The system is fabricated monolithically using an in-house surface micromachining process on a glass substrate and occupies an area of 6 cm times 5 cm. The measurement results show that the phase shifter can provide nearly 20deg/50deg/95deg phase shifts and their combinations at the expense of 1.5-dB average insertion loss at 15 GHz for eight combinations. It is also shown by measurements that the main beam can be steered to required directions by suitable settings of the RF MEMS phase shifters.     

0.13-μm CMOS Phase Shifters for X-, Ku-, and K-Band Phased Arrays

Two 4-bit active phase shifters integrated with all digital control circuitry in 0.13-mum RF CMOS technology are developed for X- and Ku-band (8-18 GHz) and K-band (18-26 GHz) phased arrays, respectively. The active digital phase shifters synthesize the required phase using a phase interpolation process by adding quadrature-phased input signals. The designs are based on a resonance-based quadrature all-pass filter for quadrature signaling with minimum loss and wide operation bandwidth. Both phase shifters can change phases with less than about 2 dB of RMS amplitude imbalance for all phase states through an associated DAC control. For the X- and Ku-band phase shifter, the RMS phase error is less than 10^o over the entire 5-18 GHz range. The average insertion loss ranges from to at 5-20 GHz. The input for all 4-bit phase states is typically at -5.4 plusmn1.3 GHz in the X- and Ku-band phase shifter. The K-band phase shifter exhibits 6.5-13 of RMS phase error at 15-26 GHz. The average insertion loss is from 4.6 to at 15-26 GHz. The input of the K-band phase shifter is at 24 GHz. For both phase shifters, the core size excluding all the pads and the output 50 Omega matching circuits, inserted for measurement purpose only, is very small, 0.33times0.43 mm² . The total current consumption is 5.8 mA in the X- and Ku-band phase shifter and 7.8 mA in the K-band phase shifter, from a 1.5 V supply voltage.     

Fabrication and accelerated hermeticity testing of an on-wafer package for RF MEMS

A hermetic silicon micromachined on-wafer dc-to-40-GHz packaging scheme for RF microelectromechanical systems (MEMS) switches is presented. The designed on-wafer package has a deembedded insertion loss of 0.03 dB per transition up to 40 GHz (a total measured loss of 0.3 dB including a 2.7-mm-long through line) and a return loss below -18dB up to 40 GHz. The hermeticity of the packaged is tested using an autoclave chamber with accelerated conditions of 130/spl deg/C, 2.7 atm of pressure, and 100% relative humidity. The fabrication process is designed so as to be completely compatible with the MEMS switch process, hence, allowing the parallel fabrication of all the components on a single wafer. The on-wafer proposed packaging approach requires no external wiring to achieve signal propagation and, thus, it has the potential for lower loss and better performance at higher frequencies.     

RF MEMS技术对小型化雷达的作用

该文采用至上而下的方式,介绍了应用RF MEMS技术的雷达系统,将雷达子系统与RF MEMS技术联系起来,具体分析了应用于雷达的RF MEMS开关、移相器、滤波器和谐振器。同时,文中以开关和移相器为例,讨论了如何提高RFMEMS雷达的性能:修改空气桥形状可以提高RF MEMS收发(T/R)组件的功率处理能力,从而减少雷达相控阵的T/R组件数量;缩短转换时间的RF MEMS移相器能够应用于高速电扫描阵列;蜿蜒型5位分布式MEMS传输线移相器面积仅为5.36mm×4.72mm,相比传统移相器长度降低70%,易于实现雷达阵列的小型化。     

Design and performance of a Ka-band monolithic phase shifterutilizing nonresonant FET switches

This paper describes design consideration and performance of a Ka-band monolithic phase shifter utilizing nonresonant FET switches. The switches show broad-band on/off characteristics up to 60 GHz without using inductors; thus, robust circuit design is possible for a switched-line phase shifter. To determine circuit topology, we introduce a schematic design approach. As a result, desired phase shift as well as good matching characteristics can be realized. The developed 4-bit monolithic phase shifter demonstrates an overall phase deviation less than 5° rms and an insertion loss variation less than 0.65 dB rms from 33 to 35 GHz. For all 16 states, the insertion loss is measured to be 13.1±1.1 dB and the VSWR is less than 1.6. The chip size of the monolithic phase shifter is 2.5 mm×2.2 mm