1,720,963 research outputs found
Reliability test of a RF MEMS varactor based on a double actuation mechanism
No full textThis paper presents the design and reliability tests of a novel micro-electro mechanical varactor based on a double actuation mechanism allowing for overall capacitive ratio Cr of 5.2 and continuous capacitive ratio Cr* of 2.6. The device has been modeled in ANSYS® multiphysics environment and manufactured by using the 8-masks FBK-irst RF MEMS process. The performance was tested on 10 samples showing good mechanical reproducibility and negligible capacitance ratios variation (Cr =5.2 ± 5%, Cr*=2.6 ± 4%). Self-biasing tests have been performed by applying an equivalent Vrms on the RF central conductor, showing an insignificant capacitance ratio variation up to 13.5Vrms. Finally, cycling test was performed on the DUT up to 108 cycles, showing negligible variation of the capacitance
MEMS-based LC tank with extended tuning range for multiband applications
No full textThis paper presents the modeling, simulations, and measurements of a compact multiband microelectromechanical (MEMS)-based LC tank resonator suitable for low phase noise voltage-controlled oscillators (VCOs). The resonator is based on a high-Q spiral inductor and high capacitance ratio varicap fully integrated in FBK-irst (Fondazione Bruno Kessler) MEMS manufacturing process. The design of the varicap is based on double-actuation mechanism with a mechanical central bond that inhibits the pull-in allowing for a theoretically infinite tuning ratio. The measurements have shown a total not continuous capacitance ratio (Cr) of 5.2 with a continuous variation of the capacitance values in the range 225 fF–600 fF which corresponds to a continuous capacitance ratio (Cr*) of 2.6. The performance repeatability, the power-handling capability, and the stability over time were tested on 10 samples showing a negligible variation of the capacitance values. The spiral inductor consists of a suspended gold membrane thick 5 μm in a circular shape which was modeled in order to optimize the quality factor (Q) in the frequency range 2–4 GHz. The measurement results show a Q of about 55 in the 2–4 GHz frequency band. The LC tank measurements show an overall tuning range better than of 45% in the 3.2–4.9 GHz frequency band, consisting of two continuous tuning ranges of 7.5% and 25%. The LC tank allowed the design of MEMS-based voltage-controlled oscillators (VCOs) with an overall tuning better than 60% in the frequency range 2.15 GHz–3.85 GHz and two separate regions of continuous tuning range. The VCO prototype will be fabricated on Surface Mount Technology on RO4350 laminate. The main figures of merit are presented in comparison with the state of the art
MEMS-based LC tank with extended tuning range for low phase-noise VCO
No full textThis paper presents the modeling, manufacturing, and testing of a micro-electromechanical system (MEMS)-based LC tank resonator suitable for low phase-noise voltage-controlled oscillators (VCOs). The device is based on a variable MEMS varactor in series with an inductive coplanar waveguide line. Two additional parallel stubs controlled by two ohmic MEMS switches have been introduced in order to increase the resonator tunability. The device was fabricated using the FBK-irst MEMS process on high resistivity (HR) silicon substrate. Samples were manufactured with and without a 0-level quartz cap. The radio frequency characterization of the devices without 0-level cap has shown a continuous tuning range of 11.7% and a quality factor in the range of 33-38. The repeatability was also tested on four samples and the continuous tuning is 11.7 ± 2%. Experimental results on the device with a 0-level cap, show a frequency downshift of about 200 MHz and a degradation of the quality factor of about 20%. This is, most likely, due to the polymeric sealing ring as well as to a contamination of the ohmic contacts introduced by the capping procedure. A preliminary design of a MEMS-based VCO was performed using Advanced Design System and a hardwired prototype was fabricated on Surface Mount Technology on RO4350 laminate. The prototype was tested resulting in a resonance frequency of 5 GHz with a phase noise of -105 and -126 dBc at 100 KHz and 1 MHz, respectively, and a measured output power of -1 dBm. © 2015 Cambridge University Press and the European Microwave Association
Design and manufacturing of X-Band tunable microcavity resonator in MEMS technology
Full text linkThis paper presents the design modeling and
hardwire prototypes fabrication of a X-band tunable cavity
resonator based on MEMS technology. Brass metallic
cavities with inner post have been thermo-compressive
bonded on a silicon substrates having 4 MEMS varactors
based on toggle mechanism. The tunable resonator was
simulated in ANSYS® HFSS full wave environment,
resulting in a continuous tuning range of 22% with an
unloaded quality factor (Q) in the range of 80-180 and a
very small volume of 3.2x3.2x1.4 mm3. Preliminary
experimental results are presented. The measurements on
hardwired prototypes result in a maximum unloaded
quality factor (Q) of 80 and tuning range of 14%, centered
at the frequency of about 9GHz. The main responsible of the
lower measured quality factor, respect to the simulated one,
was found to be the additional losses in the silicon substrate
Low Complexity UWB Radios for Precise Wireless Sensor Network Synchronization
No full textWireless sensor networks are becoming widely diffused because of the flexibility and scalability they offer. However, distributed measurements are significant only if the readout is coupled to time information. For this reason, network-wide time synchronization is the main concern. The objective of this paper is to exploit a very simple hardware implementation of an IR-UWB radio for realizing an accurate synchronization system for wireless sensors. The proposed solution relies on commercial-off-the-shelf discrete electronic components (rather than on specialized transceivers). It is designed for providing accurate timestamping of the packet time of arrival (TOA) to an adder-based tunable clock, which tracks the network time reference. The comprehensive set of experimental results based on prototypes, shows a TOA detection error with a standard deviation well below 1 ns. On the other hand, in the FPGA based prototype, the synchronization performance reaches an overall synchronization error of few nanoseconds. Finally, in order to highlight the tradeoff between timestamping accuracy, clock stability, and synchronization performance, some additional simulations have been carried out: a synchronization error in the order of 1 ns is possible, if good local oscillator sources are available in the nodes and if the adjustable clock has a sufficient resolution
A 5.6-GHz UWB Position Measurement System
No full textThis paper describes the design and realization of a 5.6-GHz ultrawide-bandwidth-based position measurement system. The system was entirely made using off-the-shelf components and achieves centimeter-level accuracy in an indoor environment. It is based on asynchronous modulated pulse round-trip time measurements. Both system level and realization details are described along with experimental results including estimates of measurement uncertainties
MEMS-based LC tank with extended tuning range for low phase-noise VCO
No full textThis paper presents the modeling, manufacturing, and testing of a micro-electromechanical system (MEMS)-based LC tank resonator
suitable for low phase-noise voltage-controlled oscillators (VCOs). The device is based on a variable MEMS varactor in
series with an inductive coplanar waveguide line. Two additional parallel stubs controlled by two ohmic MEMS switches have
been introduced in order to increase the resonator tunability. The device was fabricated using the FBK-irst MEMS process on
high resistivity (HR) silicon substrate. Samples were manufactured with and without a 0-level quartz cap. The radio frequency
characterization of the devices without 0-level cap has shown a continuous tuning range of 11.7% and a quality factor in the
range of 33–38. The repeatability was also tested on four samples and the continuous tuning is 11.7+2%. Experimental
results on the device with a 0-level cap, show a frequency downshift of about 200 MHz and a degradation of the quality factor
of about 20%. This is,most likely, due to the polymeric sealing ring as well as to a contamination of the ohmic contacts introduced
by the capping procedure.Apreliminary design of aMEMS-basedVCOwas performed usingAdvancedDesign Systemand a hardwired
prototype was fabricated on Surface Mount Technology on RO4350 laminate. The prototype was tested resulting in a resonance
frequency of 5 GHz with a phase noise of 2105 and 2126 dBc at 100 KHz and 1 MHz, respectively, and a measured
output power of 21 dBm
Woodchip humidity measurements using EM pulse propagation time
No full textIn this paper, a system for measuring moisture content of wood-chip samples is presented, based on propagation time measurements of electromagnetic pulses in a two wire probe. Both simulation and experimental results are reported, validated by concurrently performed TGA measurements. It is shown that the proposed approach may be advantageous, since it features a good sensitivity and a very high measurement speed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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