It is shown that radiofrequency micro-electromechanical-system (RF-MEMS) switches are useful to implement electronically reconfigurable split ring resonators (SRRs). Three different combinations of ...cantilever-type ON/OFF capacitive switches with SRRs are studied for the design of tunable or switchable SRR-loaded metamaterial transmission lines. These structures are then applied to the design of reconfigurable band stop and band pass filters at the X-frequency band. Through electrostatic actuation of the switches, the resonance frequency of SRRs can be shifted and, as a result, filter bandwidth and/or central frequency can be digitally controlled. Good agreement between theory and experiment is achieved.
This paper presents the fabrication and measurements of RF-MEMS, zero-level packaged switched capacitors. Crystallized Ta/Ta 2 O 5 electrodes are used for electrostatic actuation. The electrode ...formation is conducted in a single deposition step, providing a very good metal (Ta) to dielectric (Ta 2 O 5 ) interface. The 60×50 µm MEMS capacitor can be switched from 50 fF to 350 fF, by applying a 15 V unipolar bias voltage. 8-hours hold-down testing have shown the absence of charging. The high permittivity of Ta 2 O 5 also increases 5 times the capacitance value compared to SiN-based switched MEMS capacitors with the same surface.
We present the non-linear electrical properties of simple two-terminal switching devices based on vanadium dioxide (VO2) thin films. The current–voltage characteristics of such devices present ...negative differential resistance (NDR) regions allowing generating electrical self-oscillations across the investigated devices, with frequencies ranging from several kHz up to 1 MHz. We investigate and compare the factors determining the onset of oscillatory phenomenon in both voltage- and current-activated oscillations and explain its origin. For both activation modes, we will correlate the properties of electrical oscillations (amplitude and frequency) with the amplitude of the continuous excitation signal, the physical geometry of the devices or ambient temperature. We conclude by mentioning several possible applications for the oscillation generation in the radiofrequency (RF)/microwave domains (inverters, integrated a.c. signal generators, pressure and temperature sensors, etc.).
This paper presents a new mechanical architecture for RF MEMS components that are able to achieve reconfiguration faster than conventional MEMS switches. For most MEMS switches, the electrical ...switching speed is generally limited to a few microseconds, inherently restricted by the delay required to mechanically move their mobile membrane up and down. By using a proper mechanical design and the structural material fabrication process, this paper will show miniature bridges that are able to exhibit mechanical resonance frequencies over 10 MHz range to be compared to the few tens of kHz for conventional RF MEMS switches. As a result, the switching speed of these miniature components is greatly improved and reaches 50 to 100 ns. Such performance has been achieved using composite micro-beams based on the multilayer material assembly of alumina/aluminum/alumina. To our knowledge, this is the fastest switching speed reported for RF MEMS components so far.
We present our current researches on phase transition materials (vanadium dioxide, VO2) performing a thermally- or electrically-triggered metal-insulator transition and on chalcogenide ...amorphous-to-crystalline phase change materials like GeTe or Ge 2 Sb 2 Te 5 and we will focus on their tunable electrical and optical properties for applications in different domains spanning from DC to millimeter waves, THz and optics
We present the optical switching of the GeTe phase change material between its insulated and conductive states using short (~ 30 ns) single UV laser pulses. The material was integrated in ...high-frequency switches which can be optically toggled between their ON and OFF-states in a bi-stable manner on large frequency bands, up to 67 GHz.
Millimeter-wave tune-all bandpass filters Mercier, D.; Orlianges, J.-C.; Delage, T. ...
IEEE transactions on microwave theory and techniques,
2004-April, 2004-04-00, 20040401, Letnik:
52, Številka:
4
Journal Article
Recenzirano
Distributed microelectromechanical varactors on a coplanar waveguide have been used to design a two- and four-pole bandpass tune-all filters. The two-pole initial bandwidth is 6.4% at 44.05 GHz with ...a mid-band insertion loss of 3.2 dB and with matching better than 15 dB. The four-pole initial bandwidth is 6.1% at 43.25 GHz with a mid-band insertion loss of 6.5 dB and with matching better than 10 dB. The use of microelectromechanical system bridges allows a continuous tuning for both center frequency and bandwidth. The varactors biasing network has been designed so that the center frequency and bandwidth can be tuned separately. The two-pole filter center frequency can be changed from 44.05 to 41.55 GHz (5.6% tuning range), while the bandwidth can be independently changed from 2.8 to 2.05 GHz. The four-pole filter center frequency can be changed from 43.25 to 40.95 GHz (5.3% tuning range) and the bandwidth can be changed from 2.65 to 1.9 GHz.
A study of phase-sensitive surface plasmon resonance detection through enhanced optical signal changes by ultrathin nanomaterials is presented. The precise tuning of metallic substrate and phase ...change material-coated substrate for strong plasmon excitation were systematically investigated via both experimental measurements and theoretical calculations. The evaluations of different plasmonic sensing substrates were carried out through angular and phase-related position scanning methods. The sensing performances of Au and Ge 2 Sb 2 Te 5 (GST) thin films have been compared especially in terms of the phase singularity-related position shifts induced by the targeted sample solutions. These results paved a way for the development of stable and ultrasensitive plasmonic devices for clinical diagnostic and environmental monitoring applications.
We designed an enhanced plasmonic sensing device based on 2D Ge 2 Sb 2 Te 5 phase change nanomaterials. The sensing capability has been experimentally demonstrated to be 7000, 000 μm/RIU with a ...detection limit of 10 fM for BSA molecules.
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