A non-obtrusive technique to characterize dielectric charging in RF-MEMS capacitive switches

Degradation and failure due to dielectric charging has been a dominant and pervasive reliability concern for RF-MEMS switches. Traditionally, the operational lifetime dictated by this degradation phenomenon is extrapolated from a series of measurements of time-dependent shifts in Capacitance-Voltage (C-V) characteristics under accelerated stress conditions. In this paper, we explain why the classical large-signal C-V methodology may lead to a pessimistic under-prediction of device lifetime. Using both simulations and experiments, we propose and verify a new small-signal characterization technique based on resonance characteristics of MEMS cantilever beams. This new technique overcomes the limitations of the classical approaches to accurately anticipate device lifetime and opens up the possibility of non-obtrusive, in-situ runtime monitoring of degradation in RF-MEMS switches. Moreover, since the technique is amenable to `parallel\u27 implementation, it has the potential to be used both as an in-line process monitor as well as to reduce the overall time to technology qualification

Design of controlled RF switch for beam steering antenna array

YesA printed dipole antenna integrated with a duplex RF switch used for mobile base station antenna beam steering is presented. A coplanar waveguide to coplanar strip transition was adopted to feed the printed dipole. A novel RF switch circuit, used to control the RF signal fed to the dipole antenna and placed directly before the dipole, was proposed. Simulated and measured data for the CWP-to-CPS balun as well as the measured performance of the RF switch are shown. It has demonstrated the switch capability to control the beam in the design of beam steering antenna array for mobile base station applications

Mixed-Domain Fast Simulation of RF and Microwave MEMS-based Complex Networks within Standard IC Development Frameworks

MS technology (MicroElectroMechanical-System) has been successfully employed since a few decades in the sensors/actuators field. Several products available on the market nowadays include MEMS-based accelerometers and gyroscopes, pressure sensors and micro-mirrors matrices. Beside such well-established exploitation of MEMS technology, its use within RF (Radio Frequency) blocks and systems/sub-systems has been attracting, in recent years, the interest of the Scientific Community for the significant RF performances boosting that MEMS devices can enable. Several significant demonstrators of entirely MEMS-based lumped components, like variable capacitors (Hyung et al., 2008), inductors (Zine-El-Abidine et al., 2003) and micro-switches (Goldsmith et al., 1998), are reported in literature, exhibiting remarkable performance in terms of large tuning-range, very high Q-Factor and low-loss, if compared with the currently used components implemented in standard semiconductor technology (Etxeberria & Gracia, 2007, Rebeiz & Muldavin, 1999). Starting from the just mentioned basic lumped components, it is possible to synthesize entire functional sub-blocks for RF applications in MEMS technology. Also in this case, highly significant demonstrators are reported and discussed in literature concerning, for example, tuneable phase shifters (Topalli et al., 2008), switching matrices (Daneshmand & Mansour, 2007), reconfigurable impedance matching networks (Larcher et al., 2009) and power attenuators (Iannacci et al., 2009, a). In all the just listed cases, the good characteristics of RF-MEMS devices lead, on one side, to very highperformance networks and, on the other hand, to enabling a large reconfigurability of the entire RF/Microwave systems employing MEMS sub-blocks. In particular, the latter feature addresses two important points, namely, the reduction of hardware redundancy, being for instance the same Power Amplifier within a mobile phone suitable both in transmission (Tx) and reception (Rx) (De Los Santos, 2002), and the usability of the same RF apparatus in compliance with different communication standards (like GSM, UMTS, WLAN and so on) (Varadan, 2003). Beside the exploitation of MEMS technology within RF transceivers, other potentially successful uses of Microsystems are in the Microwave field, concerning, e.g., very compact switching units, especially appealing to satellite applications for the very reduced weight (Chung et al., 2007), and phase shifters in order to electronically steer short and mid-range radar systems for the homeland security and monitoring applications (Maciel et al., 2007). Given all the examples reported above, it is straightforward that the employment of a proper strategy in aiming at the RF-MEMS devices/networks optimum design is a key-issue in order to gain the best benefits, in terms of performance, that such technology enables to address. This is not an easy task as the behaviour of RF-MEMS transversally crosses different physical domains, namely, electrical, mechanical and electromagnetic, leading to a large number of trade-offs between mechanical and electrical/electromagnetic parameters, that typically cannot be managed within a unique commercial simulation tool. In this chapter, a complete approach for the fast simulation of single RF-MEMS devices as well as of complex networks is presented and discussed in details. The proposed method is based on a MEMS compact model library, previously developed by the author, within a commercial simulation environment for ICs (integrated circuits). Such software tool describes the electromechanical mixed-domain behaviour typical of MEMS devices. Moreover, through the chapter, the electromagnetic characteristics of RF-MEMS will be also addressed by means of extracted lumped element networks, enabling the whole electromechanical and electromagnetic design optimization of the RF-MEMS device or network of interest. In particular, significant examples about how to acc..

Study and Design of Reconfigurable Wireless and Radio- Frequency Components Based on RF MEMS for Low-Power Applications

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

An ohmic RF MEMS switch for reconfigurable microstrip array antennas built on PCB

This paper presents the analysis, design and simulation of an ohmic RF MEMS switch specified for reconfigurable microstrip array antennas built on PCB via an integrated monolithic technology. The proposed switch will be used to allow antenna beamforming in the operating frequency range between 2.4GHz and 4GHz. This application requires a great number of these switches to be integrated with an array of microstrip patch elements. The proposed switch exhibits outstanding switching characteristics, following a relatively simple design, which ensures reliability, robustness and high fabrication yield

On the design of an Ohmic RF MEMS switch for reconfigurable microstrip antenna applications

This paper presents the analysis, design and simulation of a direct contact (dc) RF MEMS switch specified for reconfigurable microstrip array antennas. The proposed switch is indented to be built on PCB via a monolithic technology together with the antenna patches. The proposed switch will be used to allow antenna beamforming in the operating frequency range between 2GHz and 4GHz. This application requires a great number of these switches to be integrated with an array of microstrip patch elements. The proposed switch fulfills the switching characteristics as concerns the five requirements (loss, linearity, voltage/power handling, small size/power consumption, temperature), following a relatively simple design, which ensures reliability, robustness and high fabrication yiel

RF-MEMS Switch Module in a 0.25 µm SiGe:C BiCMOS Process

Drahtlose Kommunikationstechnologien im Frequenzbereich bis 6 GHz wurden in der Vergangenheit in Bezug auf Leistungsfaehigkeit und Frequenzbereich kontinuierlich verbessert. Aufgrund der Skalierung nach dem Mooreschen Gesetz koennen heutzutage mm-Wellen Schaltkreise in CMOS-Technologien hergestellt werden. Durch die Einfuehrung von SiGe zur Realisierung einer leistungsfaehigen BiCMOS-Technologie wurde ebenfalls eine Verbesserung der Frequenzeigenschaften und Ausgangsleistungen erreicht, wodurch aktive CMOS- oder BiCMOS-Bauelemente vergleichbare Leistungsparameter zu III-V Technologien bei geringeren Kosten bereitstellen koennen. Bedingt durch das niederohmige Silizium-Substrat der BiCMOS-Technologie weisen vor allem passive Komponenten hoehere Verluste auf und weder III-V- noch BiCMOS-Technologien bieten hochlineare Schaltkomponenten mit geringen Verlusten und geringen Leistungsaufnahmen im mm-Wellen Bereich. RF-MEMS Schalter sind bekannt fuer ihre ausgezeichneten HF-Eigenschaften. Die Leistungsaufnahme von elektrostatisch angetriebenen RF-MEMS Schaltern ist vernachlaessigbar und es koennen im Vergleich zu halbleiter-basierten Schaltern hoehere Leistungen verarbeitet werden. Nichtsdestotrotz wurden RF-MEMS Schalter hauptsaechlich als eigenstaendige Komponenten entwickelt. Zur Systemintegration wird meist ein System-in-Package (SiP) Ansatz angewandt, der fuer niedrige Frequenzen geeignet ist, aber bei mm-Wellenanwendungen durch parasitaere Verluste an seine Grenzen stoesst. In dieser Arbeit wird ein in eine BiCMOS-Technologie integrierter RF-MEMS Schalter fuer mm-Wellen Anwendungen gezeigt. Das Design, die Integration und die experimentellen Ergebnisse sowie verschiedene Packaging-Konzepte werden beschrieben Zur Bereitstellung der hohen Auslenkungs-Spannungen wurde eine Ladungspumpe auf dem Chip integriert. Zum Schluss werden verschiedene, rekonfigurierbare mm-Wellen Schaltkreise zur Demonstration der Leistungsfaehigkeit des Schalters gezeigt.Wireless communication technologies have continuously advanced for both performance and frequency aspects, mainly for the frequencies up to 6 GHz. The results of Moore’s law now also give the opportunity to design mm-wave circuits using advanced CMOS technologies. The introduction of SiGe into CMOS, providing high performance BiCMOS, has also enhanced both the frequency and the power performance figures. The current situation is that the active devices of both CMOS and BiCMOS technologies can provide performance figures competitive with III-V technologies while having still the advantage of low cost. However, similar competition cannot be pronounced for the passive components considering the low-resistive substrates of BiCMOS technologies. Moreover, both III-V and BiCMOS technologies have the lack of low-loss and low-power consumption, as well as highly linear switching and tuning components at mm-wave frequencies. RF-MEMS switch technologies have been well-known with excellent RF- performance figures. The power consumption of electrostatic RF-MEMS switches is negligible and they can handle higher power levels compared to their semiconductor counterparts. However, RF-MEMS switches have been mostly demonstrated as standalone processes and have started to be used as commercial off-the-shelf (COTS) devices recently. The full system integration is typically done by a System-in-Package (SiP) approach. Although SiP is suitable for lower frequencies, the packaging parasitics limit the use of this approach for the mm-wave frequencies. In this thesis, a fully BiCMOS embedded RF-MEMS switch for mm-wave applications is proposed. The design, the implementation and the experimental results of the switch are provided. The developed RF-MEMS switch is packaged using different packaging approaches. To actuate the RF-MEMS switch, an on-chip high voltage generation circuit is designed and characterized. The robustness and the reliability performance of the switch are also presented. Finally, the developed RF-MEMS switch is successfully demonstrated in re-configurable mm-wave circuits

Bi-stable RF-MEMS Switched Capacitor Based on Metal-to-Metal Stiction

International audienceThis paper presents a new concept for the realization of a bi-stable RF-MEMS switched capacitor using a resistive contact. The main idea is to maintain the device in a given position using metal-to-metal stiction. The metal-to-metal contact is used only for mechanical purposes and has no electrical function. 20 Volts, 10 μsec pulses are used to switch the device from one stable position to the other. After disconnection, the device maintains its position with extremely little change over long periods. 0.06% on-state capacitance relative shift has been measured over 4 days with daily control, and lab environment closet storage. 5 minutes periodic cycling shows very little drift in both states of the RF-MEMS capacitor. Moreover, the device is fabricated using MEMS conventional processing steps permits to obtain capacitive contrast of 3

Efficient Ultra High Voltage Controller Based Complementary Metal Oxide Semiconductor Switched Capacitor DC-DC Converter For Radio Frequency Micro Electro Mechanical Systems Switch Actuation

Achieving wireless connectivity in ever smaller, lower power portable devices with increasing number of features and better radio-frequency (RF) performance is becoming difficult to fulfill through existing RF front-end technology. RF micro-electro-mechanical systems (MEMS) switch technology, which has significantly better RF characteristics than conventional technology and has near-zero power consumption, is one of the emerging solutions for next generation RF front-ends. However, to achieve satisfactory RF MEMS device performance, it is often necessary to have an actuating circuitry to generate high direct current (DC) voltages for device actuation with low power consumption. In this study, the authors present an RF MEMS switch controller based on a switched-capacitor (SC) DC-DC converter in a 0.35 μm CMOS technology. In this design, novel design techniques for a higher output voltage and lower power consumption in a smaller die area are proposed. The authors demonstrate the design of the high-voltage (HV) SC DC-DC converter by using low-voltage transistors and address reliability issues in the design. Through the proposed design techniques, the SC DC-DC converter achieves more than 25% higher boosted voltage compared to converters that use HV transistors. The proposed design provides 40% power reduction through the charge recycling circuit. Moreover, the SC DC-DC converter achieves 45% smaller than the area of the conventional converter