861 research outputs found
Evaluation of MEMS Structures with Directional Characteristics Based on FRAT and Lifting Wavelet
Steps and grooves, which have typical directional characteristic, are two main functional structures of MEMS (Micro-Electro-Mechanical Systems). This paper proposes a method for analysis and evaluation of MEMS steps and grooves based on finite radon transform (FRAT) and lifting wavelet. The method consists of three steps. Firstly, FRAT is adopted to detect the directional characteristic of a MEMS structure. Secondly, on the basis of the directional characteristic obtained, the profiles of the MEMS structure are analyzed by lifting wavelet. Finally, Histogram-fitting is employed for areal evaluation of a MEMS structure. Simulated and experimental results show that MEMS structures with directional characteristic can be extracted and evaluated by the method effectively
Low Voltage Totally Free Flexible RF MEMS Switch With Anti-Stiction System
This paper concerns a new design of RF MEMS switch combined with an
innovative process which enable low actuation voltage (<5V) and avoid stiction.
First, the structure described with principal design issues, the corresponding
anti-stiction system is presented and FEM simulations are done. Then, a short
description of the process flow based on two non polymer sacrificial layers.
Finally, RF measurements are presented and preliminary experimental protocol
and results of anti-stiction validation is detailed. Resulting RF performances
are -30dB of isolation and -0.45dB of insertion loss at 10 GHz.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
Optomechanical zipper cavity lasers: theoretical analysis of tuning range and stability
The design of highly wavelength tunable semiconductor laser structures is
presented. The system is based on a one dimensional photonic crystal cavity
consisting of two patterned, doubly-clamped nanobeams, otherwise known as a
"zipper" cavity. Zipper cavities are highly dispersive with respect to the gap
between nanobeams in which extremely strong radiation pressure forces exist.
Schemes for controlling the zipper cavity wavelength both optically and
electrically are presented. Tuning ranges as high as 75nm are achieved for a
nominal design wavelength of 1.3micron. Sensitivity of the mechanically
compliant laser structure to thermal noise is considered, and it is found that
dynamic back-action of radiation pressure in the form of an optical or
electrical spring can be used to stabilize the laser frequency. Fabrication of
zipper cavity laser structures in GaAs material with embedded self-assembled
InAs quantum dots is presented, along with measurements of photoluminescence
spectroscopy of the zipper cavity modes.Comment: 20 pages, 8 figure
Readout Method And Electronic Bandwidth Control For A Silicon In-plane Tuning Fork Gyroscope
Disclosed are methods and a sensor architecture that utilizes the residual quadrature error in a gyroscope to achieve and maintain perfect mode-matching, i.e., ~0 Hz split between the drive and sense mode frequencies, and to electronically control sensor bandwidth. In a reduced-to-practice embodiment, a 6 mW, 3V CMOS ASIC and control algorithm are interfaced to a mode-matched MEMS tuning fork gyroscope to implement an angular rate sensor with bias drift as low as 0.15°/hr and angle random walk of 0.003°/√hr, which is the lowest recorded to date for a silicon MEMS gyroscope. The system bandwidth can be configured between 0.1 Hz and 1 kHz.Georgia Tech Research Coporatio
A closed-loop digitally controlled MEMS gyroscope with unconstrained Sigma-Delta force-feedback
In this paper, we describe the system architecture and prototype measurements of a MEMS gyroscope system with a resolution of 0.025 degrees/s/root Hz. The architecture makes extensive use of control loops, which are mostly in the digital domain. For the primary mode both the amplitude and the resonance frequency are tracked and controlled. The secondary mode readout is based on unconstrained Sigma Delta force-feedback, which does not require a compensation filter in the loop and thus allows more beneficial quantization noise shaping than prior designs of the same order. Due to the force-feedback, the gyroscope has ample dynamic range to correct the quadrature error in the digital domain. The largely digital setup also gives a lot of flexibility in characterization and testing, where system identification techniques have been used to characterize the sensors. This way, a parasitic direct electrical coupling between actuation and readout of the mass-spring systems was estimated and corrected in the digital domain. Special care is also given to the capacitive readout circuit, which operates in continuous time
Novel Bonding technologies for wafer-level transparent packaging of MOEMS
Depending on the type of Micro-Electro-Mechanical System (MEMS), packaging
costs are contributing up to 80% of the total device cost. Each MEMS device
category, its function and operational environment will individually dictate
the packaging requirement. Due to the lack of standardized testing procedures,
the reliability of those MEMS packages sometimes can only be proven by taking
into consideration its functionality over lifetime. Innovation with regards to
cost reduction and standardization in the field of packaging is therefore of
utmost importance to the speed of commercialisation of MEMS devices. Nowadays
heavily driven by consumer applications the MEMS device market is forecasted to
enjoy a compound annual growth rate (CAGR) above 13%, which is when compared to
the IC device market, an outstanding growth rate. Nevertheless this forecasted
value can drift upwards or downwards depending on the rate of innovation in the
field of packaging. MEMS devices typically require a specific fabrication
process where the device wafer is bonded to a second wafer which effectively
encapsulates the MEMS structure. This method leaves the device free to move
within a vacuum or an inert gas atmosphere.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Characterization and Modeling of an Electro-thermal MEMS Structure
Thermal functional circuits are an interesting and perspectivic group of the
MEMS elements. A practical realization is called Quadratic Transfer
Characteristic (QTC) element which driving principle is the Seebeck-effect. In
this paper we present the analyses of a QTC element from different
perspectives. To check the real behavior of the device, we measured a few,
secondary properties of the structure which correspond to special behavior
because these properties can not be easily derived from the main
characteristics.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
Modelling methodology of MEMS structures based on Cosserat theory
Modelling MEMS involves a variety of software tools that deal with the
analysis of complex geometrical structures and the assessment of various
interactions among different energy domains and components. Moreover, the MEMS
market is growing very fast, but surprisingly, there is a paucity of modelling
and simulation methodology for precise performance verification of MEMS
products in the nonlinear regime. For that reason, an efficient and rapid
modelling approach is proposed that meets the linear and nonlinear dynamic
behaviour of MEMS systems.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
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