Department of Electrical Engineering

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IIT Jodhpur

Novel designs of RF MEMS SP4T and SP6T switches with improved performance are reported. The design optimization carried out having significant impact on the RF characteristics of these switches. The device takes advantage of the CPW transmission line with small width and spacing configured for 50Ω with ohmic-contact SPST switch. The results show significant improvement in insertion loss and isolation without any significant changes in other electromechanical and RF parameters. A systematic comparison of different configurations of CPW designs and SPST switch is performed. The simulated insertion loss and isolation are better than -0.238 dB and - 53.002 dB respectively for SP4T switch and - 0.2956 dB and -57.217 dB respectively for SP6T switch, at 8 GHz. © 2010 IEEE.

World University root node

Proceedings - 3rd International Conference on Emerging Trends in Engineering and Technology, ICETET 2010

Design optimization of RF MEMS SP4T and SP6T switch

Sliding Mode Control (SMC) is a unique control strategy that emerged from Variable Structure Control. The chattering in 1-Sliding Mode Control was a major limitation in real world applications in spite of its proven superiority in handling disturbances and uncertainties. The Higher-Order Sliding Mode(HOSM) methods gained popularity with their ability to eliminate chattering. But the current literature available on HOSM is overly complex and difficult to grasp for a practicing engineer. The purpose of this paper is to present the concept in a simplified manner. A reaching law based approach for designing 2-sliding controller is explained and evaluated with examples. ©2010 IEEE.

Proceedings of the IEEE International Conference on Industrial Technology

A simple reaching law based design method for 2-sliding mode control

This paper presents a design method of a discrete-time reduced-order observer using the duality to discrete-time sliding-surface design. First, the duality between the coefficients of the discrete-time reduced-order observer and the sliding-surface design is established, and then, the design method for the observer using the Riccati equation is explained. A discrete-time sliding-mode controller based on the proposed observer is designed and tested on a laboratory-type experimental servo system. The results show the efficacy of the reduced-order observer designed by the duality concept. © 2010 IEEE.

IEEE Transactions on Industrial Electronics

Reduced-order observer design for servo system using duality to discrete-time sliding-surface design

In this paper, we propose selective estimation of least square based predictor algorithm and efficient overhead management scheme for lossless compression of digital mammograms. We exploit the characteristics of mammograms that most of the mammograms contain large number of blocks with constant gray level pixels, so a block based selective least square estimation algorithm is proposed. In our proposed algorithm if all the pixels have same intensity value in any block, then we represents those blocks by a single ('1') bit otherwise the block is decorrelated using the feed forward type of autoregressive modeling. We exploit the relationship between autoregression parameters which saves around 25% overhead burden. We have also empirically found that the AR parameters of the neighboring blocks are highly correlated and to get the best decorrelation among these parameters, median edge detector (MED) is used which gives us around 40% more saving in overhead burden. So, our proposed lossless compression algorithm for digital mammograms gives better entropy and minimum overhead burden then most of the algorithms reported in literature. ©2010 IEEE.

2010 IEEE International Conference on Bioinformatics and Biomedicine Workshops, BIBMW 2010

Selective estimation of least squares based predictor and efficient overhead management algorithm for lossless compression of digital mammograms

In this paper, we introduce the design method for multirate output feedback based frequency shaped sliding mode control. A switching type reaching law has been used for the vibration suppression of the smart structure. The frequency shaping approach is used to suppress the vibratory modes of smart structure excited during the sliding mode. © 2010 IEEE.

IEEE International Symposium on Industrial Electronics

The design and implementation of output feedback based frequency shaped sliding mode controller for the smart structure

A series of highly soluble donor-acceptor (D-A) copolymers containing N-(3,4,5-tri-ndecyloxyphenyl)-dithieno[3,2-b:2′,3′-d]pyrrole (DTP) or N-(2-decyltetradecyl)-dithieno[3,2-b:2′,3′-d]pyrrole (DTP') as donor and three different acceptors were synthesized by Stille coupling polymerizations. The optical and electrochemical properties of these copolymers were investigated, along with their use in field-effect transistors and photovoltaic devices. The band gaps (eV) estimated from UV-vis-NIR spectra and electrochemical measurements of the copolymers varied from ca. 1.5-0.5 eV, and were consistent with quantum chemical estimates extrapolated using Density Functional Theory. Bulk heterojunction photovoltaic devices made from blends of the copolymers with 3′-phenyl-3′H-cyclopropa[1,9](C60- Ih)[5,6]fullerene-3′-butanoic acid methyl ester (PCBM) (1:3 weight ratio) exhibited average powerconversion efficiencies as high as 1.3% under simulated irradiance of 73 mW/cm2.

ACS National Meeting Book of Abstracts

Dithienopyrrole-based donor-acceptor copolymers: Low gap materials for transport and photovoltaics

Nanosized hexagonal InN flower-like structures were fabricated by droplet epitaxy on GaN/Si(111) and GaN flower-like nanostructure fabricated directly on Si(111) substrate using radio frequency plasma-assisted molecular beam epitaxy. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the crystallinity and morphology of the nanostructures. Moreover, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to investigate the chemical compositions and optical properties of nano-flowers, respectively. Activation energy of free exciton transitions in GaN nano-flowers was derived to be ∼ 28.5 meV from the temperature dependent PL studies. The formation process of nanoflowers is investigated and a qualitative mechanism is proposed. © Indian Academy of Sciences.

Fulltext

Bulletin of Materials Science

Self-assembled flower-like nanostructures of InN and GaN grown by plasma-assisted molecular beam epitaxy

The indium nitride (InN)-based nanometric-objects were grown directly on a c-sapphire substrate by using plasma-assisted molecular beam epitaxy (PAMBE) at different substrate temperatures. High resolution X-ray diffraction (HRXRD) reveals the InN (0002) reflection and full width at half maximum (FWHM) found to be decreased with increasing the growth temperature. The size, height and density of the grown nanometric-objects studied by scanning electron microscopy (SEM) has remarkable differences, evidencing the decisive role of substrate temperature. Photoluminescence (PL) studies revealed that the emission energy is shifted towards the higher side from the bulk value, i.e., a blue shift in the PL spectra was observed. The temperature dependence of the PL peak position shows an "S-shaped" emission energy shift, which can be attributed to the localization of carriers in the nanometric-objects. Copyright © 2010 American Scientific Publishers.

Nanoscience and Nanotechnology Letters

Indium nitride nanometric-objects on c-sapphire grown by plasma-assisted molecular beam epitaxy

Designing of an Asymmetric RF Oscillator using Design of Experiments is presented and Taguchi Orthogonal Array is used for the same. Dependence of various physical parameters on output Quality Parameter, which is Phase Noise, is shown by curves. The improvement in Phase Noise is around 1.5 dB. All in all, Designing of an Asymmetric Oscillator is shown using Design of Experiments.

Proceedings of Papers - 5th European Conference on Circuits and Systems for Communications, ECCSC'10

Designing Asymmetric 2.2 GHz RF Oscillator by Design of Experiments using Taguchi methods

This paper presents design, fabrication and experimental characterization of monolithically integrated silicon nanowire (NW) biosensor with microfiltration device in back-to-back formation, in which NW biosensor is on front-side and microfiltration device on bottom-side, for application to cardiac biomarker detection from blood sample.