Radio Frequency Microelectromechanical System Technology Research Articles

RF MEMS on the radar

This article gives an overview of applications of radio frequency (RF) microelectromechanical system (MEMS) technology in radio detection and ranging (radar). RF MEMS components for radar include attenuators, limiters, (true-time-delay) phase shifters, transmit/receive (T/R) switches and tunable matching networks. Radar subsystems that benefit from RF MEMS technology include active electronically scanned arrays (T/R modules), passive electronically scanned arrays (lenses, reflect arrays, subarrays, and switched beamformers), and radomes. Using a bottom-up approach, the figures of merit for RF MEMS technology are related to the figures of merit for radar subsystems. The article also discusses ultrawideband RF MEMS reflect array and T/R module design as examples. First, electronically scanned array, radar and RF MEMS fundamentals are briefly introduced.

A fully integrated SOI RF MEMS technology for system-on-a-chip applications

In this paper, a silicon-on-insulator (SOI) radio-frequency (RF) microelectromechanical systems (MEMS) technology compatible with CMOS and high-voltage devices for system-on-a-chip applications is experimentally demonstrated for the first time. This technology allows the integration of RF MEMS switches with driver and processing circuits for single-chip communication applications. The SOI high-voltage device (0.7-/spl mu/m channel length, 2-/spl mu/m drift length, and over 35-V breakdown voltage), CMOS devices (0.7-/spl mu/m channel length and 1.3/-1.2 V threshold voltage), and RF MEMS capacitive switch (insertion loss 0.14 dB at 5 GHz and isolation 9.5 dB at 5 GHz) are designed and fabricated to show the feasibility of building fully integrated RF systems. The performance of the fabricated RF MEMS capacitive switches on low-resistivity and high-resistivity SOI substrates will also be compared.

Multifunctional reconfigurable MEMS integrated antennas for adaptive MIMO systems

Multi-input multi-output systems with associated technologies such as smart antennas and adaptive coding and modulation techniques enhance channel capacity, diversity, and robustness of wireless communications as has been proven by many recent research results both in theory and experiments. This article focuses on the antenna aspect of MIMO systems. In particular, we emphasize the important role of the reconfigurable antenna and its links with space-time coding techniques that can be employed for further exploitation of the theoretical performance of MIMO wireless systems. The advantages of the reconfigurable antenna compared to the traditional smart antenna are discussed. Establishment of reconfigurable antennas requires novel radio frequency microelectromechanical systems technology, which has recently been developed in the authors' group. We briefly introduce this technology with emphasis on its distinct advantages over existing silicon-based MEMS technologies for reconfigurable antennas. A reconfigurable antenna design that can change its operating frequency and radiation/polarization characteristics is described. Finally, we present the experimental and theoretical results from impedance and radiation performance characterization for different antenna configurations.

Review of radio frequency microelectromechanical systems technology

A review of radio frequency microelectromechanical systems (RF MEMS) technology, from the perspective of its enabling technologies (e.g. fabrication, RF micromachined components and actuation mechanisms) is presented. A unique roadmap is given that shows how enabling technologies, RF MEMS components, RF MEMS circuits and RF microsystems packaging are linked together; leading towards enhanced integrated subsystems. An overview of the associated fabrication technologies is given, in order to distinguish between the two distinct classes of RF microsystems' component technologies; non-MEMS micromachined and true MEMS. An extensive literature survey has been undertaken and key papers have been cited; from these, the motivations behind different RF MEMS technologies are highlighted. The importance of understanding the limitations for realising new and innovative ideas in RF MEMS is discussed. Finally, conclusions are drawn as to where future RF MEMS technology may lead. It is likely that the switch will continue to be the most important RF MEMS component, with future work investigating its enhanced functionality, subsystem integration and volume production. The focus of RF MEMS circuits will shift from the digital phase shifter to high-Q tuneable filters.