RF MEMS Based Tunable Circuit for Wireless Communication

2014

With fast development of mobile communication technology, the increasingly complex communicating environment and the crowded spectrum have raised stringent requirements on the RF front-end performance. In this paper, the influence of human body on the communication performance is analyzed. In particular, it is shown that the antenna input impedance faces huge variation in the frame of body-centric devices. Consequently, automatic impedance matching appears to be crucial to improve the performance withstand the inconstant environment. The investigation of key tunable components of RF MEMS is therefore presented. A variable capacitor with symmetric balanced structure is designed to achieve a large capacitance tuning ratio and a remarkable linearity of the C-V response. The proposed RF MEMS variable capacitor was modeled and simulated. The results show a linearity factor of 99.82% in C-V response and a large tuning ratio of 480% in a low actuation voltage range from 0V to 16.3V.

IEEE Microwave Magazine, 2004

T he application of microelectromechanical systems (MEMS) technology to radio-frequency (RF)/microwave systems is on the verge of revolutionizing wireless communications [1]. Indeed, the fact that RF MEMS enables superior passive devices, such as switches, switchable (two-state) capacitors, tunable capacitors (varactors), inductors, transmission lines and resonators, makes it a prime candidate to enable a plethora of wireless appliances operating in the home/ground, mobile, and space spheres [2], such as handsets, base stations, and satellites. The quintessential properties with which these systems are endowed are those of low power consumption and reconfigurablity. It is for these reasons that RF MEMS is believed to be a key technology to enable ubiquitous wireless connectivity. In this context, it is the aim of this article to expose the impact and status of the application of RF-MEMS switchable capacitors, varactors, and switches in the three elements of this paradigm, namely, handsets, base stations, and satellites. In particular, issues such as system-level motivation/justification for RF MEMS, device requirements, high-volume manufacturing, packaging, and state-ofthe-art performance and reliability, are presented. Part one, the preceding article, presented a discussion on the fundamentals of RF-MEMS technology, in Table 3. Average on-wafer loss for RF MEMS and GaAs FET 3-b PSs [20]. RF MEMS Phase GaAs FET Phase Frequency(GHz) Shifter Loss(dB) Shifter Loss(dB) X-band (10) −0.9 to −1.0 −3 to −4 Ka-band (35) −1.7 to −2.0 −6 to −7 V-band (60) −2.3 to −2.6 −8 to −9 W-band (90) −2.6 to −3.0 −9 to −10

2014

This paper reviews the design and development of different building blocks of RF MEMS sub-systems. The blocks include switches, tunable capacitors, integrated inductors, filters, reconfigurable circuits, phase shifters and antennas. Starting with the details of a general micromachining process, a behavioral analysis of RF MEMS components and design challenges with present state-of-the-art are discussed. Different fabrication processes are outlined and discussed. The functional behaviors of different RFMEMS components are experimentally investigated over certain frequency bands of interest and validated through system level simulation. Finally, a low cost packaging scheme has been presented.

MEMS Sensors - Design and Application

This chapter intends to deal with the challenging field of communication systems known as reconfigurable radio-frequency systems. Mainly, it will present and analyze the design of different reconfigurable components based on radio-frequency microelectromechanical systems (RF MEMS) for different applications. This chapter will start with the description of the attractive properties that RF MEMS structures offer, giving flexibility in the RF systems design, and how these properties may be used for the design of reconfigurable RF MEMS-based devices. Then, the chapter will discuss the design, modeling, and simulation of reconfigurable components based on both theoretical modeling and well-known electromagnetic computing tools such as ADS, CST-MWS, and HFSS to evaluate the performance of such devices. Finally, the chapter will deal with the design and performance assessment of RF MEMS-based devices. Non-radiating devices, such as phase shifter and resonators, which are very important components in the hardware RF boards, will be addressed. Also, three types of frequency reconfigurable antennas, for the three different applications (radar, satellite, and wireless communication), will be proposed and evaluated. From this study, based on theoretical design and electromagnetic computing evaluation, it has been shown that RF MEMS-based devices can be an enabling solution in the design of the multiband reconfigurable radio-frequency devices.

2000 IEEE Emerging Technologies Symposium on Broadband, Wireless Internet Access. Digest of Papers (Cat. No.00EX414)

2013

Microelectromechanical systems (MEMS) is the technology of very small devices which merges both mechanical and electronic devices on a monolithic microchip to produce superior performance over solid-state components, especially for wireless applications. Popular MEMS switches for wireless applications include transmit/receive duplexers, band-mode selection, time delay for phased-array antennas, and reconfigurable antennas. This paper talks about the use of MEMS switches in conjunction of fractal antennas to achieve multi-frequency, reconfigurable antennas that can be used for a variety of communication applications and how micromachining can be used to fabricate new 3-D MEMS antenna structures for very high frequency applications. KeyTermsRe-configurable antennas, Numerical integration wideband, fractal, RFMEMS.

RF-MEMS (Radio Frequency-Micro Electro Mechanical Systems) are made up of moveable and fragile components (membranes, beams, cantilevers) that must be enclosed in for protection and for stable performance characteristics. Packaging is an important technology and critical aspect for the advancement of RF-MEMS. This paper elaborates the various RF-MEMS packaging challenges in the context of environment, modeling reliability, integration, stiction etc. All these challenges are application dependent; therefore case study on RF-MEMS switches with liquid crystal polymer (LCP) enclosure is presented for an in-depth illustration. RF-MEMS have the potential to have a tremendous impact on various fields such as wireless communication, defense, aerospace, radars, satellite etc. Packaging engineers are trying to overcome the packaging issues. They are trying to develop economical high-performance and highly reliable packaging solutions. The package plays a key role in ensuring the long term rel...

The general study is dedicated to Wireless Sensor Networks. The idea is to associate micro-mechanical and microwave communication functions to exchange information between a remote sensor and a base station [1]. A specific part of this project concerns the conception, realisation, and characterisation of a passive microwave frequency shifter used for back-modulation around 2 GHz. The interesting point was to develop this function with an integrated silicon micro-mechanical rotating structure. The paper describes the prototype of the RF MEMS already developed in ESIEE laboratory. And we insist on the microwave measurements performed and the associated equivalent models.

Advances in Science and Technology, 2012

MEMS (MicroElectroMechanical-Systems) technology applied to the field of Radio Frequency systems (i.e. RF-MEMS) has emerged in the last 10-15 years as a valuable and viable solution to manufacture low-cost and very high-performance passive components, like variable capacitors, inductors and micro-relays, as well as complex networks, like tunable filters, reconfigurable impedance matching networks and phase shifters, and so on. The availability of such components and their integration within RF systems (e.g. radio transceivers, radars, satellites, etc.) enables boosting the characteristics and performance of telecommunication systems, addressing for instance a significant increase of their reconfigurability. The benefits resulting from the employment of RF-MEMS technology are paramount, being some of them the reduction of hardware redundancy and power consumption, along with the operability of the same RF system according to multiple standards. After framing more in detail the whole context of RF-MEMS technology, this paper will provide a brief introduction on a typical RF-MEMS technology platform. Subsequently, some relevant examples of lumped RF-MEMS passive elements and complex reconfigurable networks will be reported along with their measured RF performance and characteristics.

This paper deals with the RF (Radio Frequency)-MEMS (Micro-Electro-Mechanical-System) switch importance in the wireless communication system. Also explains the dominance of RF-Switch over existing devices like PIN Diodes and Field-Effect-Transistors with size, power, isolation, insertion loss, and graphically how Pull-in voltage affects on the tip deflection of the switch.