Contact RF MEMS Switch Research Articles

WITHDRAWN: Role of multiple contacts in the performance of DC contact RF MEMS switch

This communication investigates the role of uniform and non-uniform cantilever structures in the design of DC contact RF MEMS switches. The Eigen frequency exploration is performed. The cantilever structure is offering low actuation voltage. Because of multiple contacts, the switch reliability if improved significantly. The height of the cantilever is 1.5 µm and actuation voltage is 5.5 V. The designed DC contact RF MEMS switch is analyzed over the frequency range 0.5–10 GHz. The insertion loss of the switch is −0.2 dB and the isolation loss of the switch is −41 dB to −20 dB. The simulation level switch performance is analyzed using COMSOL and HFSS FEM tools.

Cantilever Based Series Metal Contact RF MEMS Switch with Reduced Pull-in voltage and RF losses

Cantilever Based Series Metal Contact RF MEMS Switch with Reduced Pull-in voltage and RF losses

Metal contact RF MEMS switch design for high performance in Ka band

RF/microwave systems require switches to achieve tunability and reconfigurability. MEMS switches have always been a priority due to excellent RF performance (low insertion loss and high isolation). In this work, we present an RF Micro-Electro-Mechanical-System (RF MEMS) series switch that provides insertion loss less than 0.6 dB (on switch) and isolation better than 15 dB (off switch) at 40GHz. The designed switch consists of serpentine arms on the fixed end and two free-moving arms on another end. These free arms have individual contact points to overcome asperity problem during on state. To avoid self-actuation, bumps (0.6um) are used at the bottom side. This electrostatically actuated switch requires a pull-in voltage of 3.1V for 2.4 μm displacement in 67.14 μs time. The proposed switch is analysed in COMSOL software, and its RF characteristics are simulated in HFSS.

Design, optimization and analysis of reconfigurable antenna using RF MEMS switch

This paper presents the design, optimization and analysis of a novel radio-frequency micro electromechanical system (RF MEMS) switch for reconfigurable antenna. The proposed antenna operates at frequency band from 4.5 to 12.5 GHz. The antenna is created by reconfiguring its size using a rectangular patch and an inverted U shaped patch via RF MEMS switch. A series metal to metal contact RF MEMS switch is designed and optimized for low actuation voltage with adequate switching speed and excellent RF characteristics. The design of RF MEMS switch is simulated using CoventorWare and RF analysis is performed on Ansys HFSS software. Pull in voltage obtained for the switch is 5.7 V with switching time of 38.7 μs. The isolation obtained is better than − 20 dB for DC to 25 GHz. Insertion loss is less than − 0.4 dB for DC to 60 GHz and return loss is also better than − 23 dB for DC to 60 GHz. Further the designed reconfigurable antenna is simulated using Ansys HFSS software. The antenna is reconfigurable at 4.5 GHz, 8.6 GHz, 9 GHz, 12.3 GHz, 12.4 GHz and 12.5 GHz for different switch positions.

A high-force and high isolation metal-contact RF MEMS switch

A simple structure, high-force and high isolation metal contact RF MEMS switch was fabricated based on micro electroplating technology, and the mechanical and RF performance of the switch were measured. After release and annealing, the switch’s cantilever beam showed a tip-up of less than 1 µm over the beam length of 485 µm, indicating a good stress control and thermal stability of the electroplated gold. The pull-in voltage and the switching characteristics at different temperatures, ranging from 25 to 90 °C, were investigated. A fast, stable and temperature independent switching process was observed as the actuation voltage was 10% larger than the pull-in voltage. Based on the classical cantilever beam model, both the electrostatic actuation force and the return force of the switch were larger than 1000 μN, and the extracted effective spring constant of the free-standing beam was 718 N/m. Cold RF tests were carried out at various temperatures by a network analyzer, and we found that temperature showed very less influence on the insertion and isolation of the switch in the present case. At 25 °C, the insertion loss was −0.13 dB at 10 GHz, and was lower than −0.3 dB over the 0.05−20 GHz frequency range. The isolation was −36 dB at 10 GHz, and was higher than −27 dB over the entire scanning frequency range. The high isolation performance is consistent with a lumped-element equivalent circuit analysis of the switch.

Design Aspects of a New Reliable Torsional Switch with Excellent RF Response

This paper proposes a metal contact RF MEMS switch which utilizes a see-saw mechanism to acquire a switching action. The switch was built on a quartz substrate and involves vertical deflection of the beam under an applied actuation voltage of 5.46 volts over a signal line. The see-saw mechanism relieves much of the operation voltage required to actuate the switch. The switch has a stiff beam eliminating any stray mechanical forces. The switch has an excellent isolation of −90.9 dB (compared to − 58 dB in conventional designs ), the insertion of −0.2 dB, and a wide bandwidth of 88 GHz (compared to 40 GHz in conventional design ) making the switch suitable for wide band applications.

Design and Fabrication of a Lateral Contact RF-MEMS Switch for MM-Wave Applications

Design, fabrication and test results of a lateral DC-contact RF-MEMS switch for mm-wave applications are presented. The switch is driven by a triple cascaded electrothermal buckle-beam actuator, which can generate large displacements and contact forces at lower temperatures than traditional electrothermal actuators. The size of the whole switch is only 1.2 mm × 1.4 mm in area. The measured transient times for switch-on and switch-off are 13.6 and 0.96 ms, respectively. Low insertion losses and high isolation of 0.17 dB and 26.7 dB, respectively, are obtained in the proposed switch at center frequency of 35GHz, the insertion losses less than 0.5dB and the isolation better than 22.5dB can be achieved in the proposed switch at 30~40GHz. The reasonable agreement between design and measurement is observed.

High isolation RF MEMS contact switch in V- and W-bands using two directional motions

Proposed is the concept of an RF MEMS contact switch with high isolation over 50 GHz, and experiment at work succeeds in showing its feasibility. High isolation was achieved using two directional motions, namely vertical and lateral movement of the contact part, contrary to typical MEMS switches that generally use one of two motions. Comb and parallel plate actuators enable the contact part to move in the lateral and vertical directions. The silicon on glass (SiOG) process is utilised to fabricate the silicon switch on a glass substrate. The RF characteristics are simulated and measured from 50-110 GHz to prove the high isolation capabilities in the V- and W-bands.

Macromodel-based simulation and measurement of the dynamic pull-in of viscously damped RF-MEMS switches

Three different state-of-the-art approaches are used to generate macromodels of an electrostatically actuated and viscously damped ohmic contact RF-MEMS switch. The capability of the three multi-energy domain coupled models to predict the behavior of the RF-MEMS switch is evaluated w.r.t. white light interferometer and laser vibrometer measurements. The different macromodels show very good agreement concerning the quasi-static measured pull-in/pull-out characteristics. The evaluation of the modeled viscous damping forces demonstrates that tailored physics-based models give significantly better results than simple generic models. However, all approaches fail in capturing the landing phase of the membrane during the dynamic pull-in correctly. Measurements revealed that this is due to the presence of a higher eigenmode that is activated during impact.

An X band RF MEMS switch based on silicon-on-glass architecture

Communication systems such as those used on satellite platforms demand high performance from individual components that make up the various systems and sub-systems. Switching and routing of RF signals between various modules is a routine and critical operation that determines the overall efficiency of the entire system. In this paper, we present the design and fabrication aspects of a direct contact RF MEMS switch designed to operate in the X band (8–12 GHz) with a target insertion of about 0·5 dB and isolation better than 30 dB. The actuation voltage is expected to be around 50 V. The die size is designed to be 3 mm (H) × 3 mm(W) × 2 mm(H). The switch is built from a low residual stress device layer of a highly conducting (0·005 Ohms-cm) silicon on insulator (SOI) wafer. After subsequent lithographic steps, the wafer is bonded to a Pyrex glass wafer which has been previously patterned with gold transmission lines and pull in electrodes. Being built from a single crystal silicon structure, the mechanical robustness of the actuator is much greater than the those in similar membrane-based devices. A 6 mask fabrication process utilizing Deep Reactive Ion Etching to achieve high aspect ratio stiction free structures was developed and implemented. Devices from the first fabrication run are being analysed in our laboratory.

Lifetime Measurements on a High-Reliability RF-MEMS Contact Switch

Radio frequency microelectromechanical systems (RF MEMS) cantilever contact switches have been tested for lifetime. The mean cycles-to-failure measured on an ensemble of switches was 430 billion switch cycles. The longest lifetime exhibited without degradation of the switch was 914 billion switch cycles. The devices were switched at 20 kHz with an incident RF frequency of 10 GHz and an incident RF power of 20 dBm. Testing was performed continuously over a period of approximately 18 months. The switches were operated in a cold-switched mode.

Reconfigurable microstrip rectangular loop antennas using RF MEMS switches

AbstractIn this article, a low‐actuation voltage DC contact RF MEMS switch is developed for a reconfigurable microstrip rectangular loop antenna implementation providing frequency tunability. Electromechanical design optimization, microfabrication through the PolyMUMPS commercial process, and RF simulation is presented. The application of such RF MEMS switches to frequency‐tunable reconfigurable microstrip loop antennas is subsequently investigated by electromagnetic full wave analysis simulation tool. The physical perimeter of the loop antenna is electronically varied by controlling the ON/OFF states of the MEMS switches. The resonance frequency of the microstrip loop antenna is shown to be reconfigurable linearly by 56% with the linear change of the physical perimeter while the radiation pattern is almost invariant. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 252–256, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23042

Modeling, simulation and measurement of the dynamic performance of an ohmic contact, electrostatically actuated RF MEMS switch

In this paper we present a 3D nonlinear dynamic model which describes the transient mechanical analysis of an ohmic contact RF MEMS switch, using finite element analysis in combination with the finite difference method. The model includes real switch geometry, electrostatic actuation, the two-dimensional non-uniform squeeze-film damping effect, the adherence force, and a nonlinear spring to model the interaction between the contact tip and the drain. The ambient gas in the package is assumed to act as an ideal and isothermal fluid which is modeled using the Reynolds squeeze-film equation which includes compressibility and slip flow. A nonlinear contact model has been used for modeling contact between the microswitch tip and the drain electrode during loading. The Johnson–Kendall–Roberts (JKR) contact model is utilized to calculate the adherence force during unloading. The developed model has been used to simulate the overall dynamic behavior of the MEMS switches including the switching speed, impact force and contact bounce as influenced by actuation voltage, damping, materials properties and geometry. Meanwhile, based on a simple undamped spring–mass system, a dual voltage-pulse actuation scheme, consisting of actuation voltage (Va), actuation time (ta), holding voltage (Vh) and turn-on time (ton), has been developed to improve the dynamic response of the microswitch. It is shown that the bouncing of the switch after initial contact can be eliminated and the impact force during contact can be minimized while maintaining a fast close time by using this open-loop control approach. It is also found that the dynamics of the switch are sensitive to the variations of the shape of the dual pulse scheme. This result suggests that this method may not be as effective as expected if the switch parameters such as threshold voltage, fundamental frequencies, etc. deviate too much from the design parameters. However, it is shown that the dynamic performance may be improved by increasing the damping force. The simulation results obtained from this dynamic model are confirmed by experimental measurement of the RF MEMS switches which were developed at the Northeastern University. It is anticipated that the simulation method can serve as a design tool for dynamic optimization of the microswitch. In addition, the approach of tailoring actuation voltage and the utilization of squeeze-film damping may provide further improvements in the operation of RF MEMS switches.