Department of Electrical Engineering

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IIT Jodhpur

In this paper, we present an additive prediction error expansion (PEE) based reversible data hiding scheme that gives overall low distortion and relatively high embedding capacity. Recently reported interpolation based PEE method uses fixed order predictor that fails to exploit the correlation between the neighborhood pixels and the unknown pixel (to be interpolated).We observed that embedding capacity and distortion of PEE based algorithm depends on the prediction accuracy of the predictor. In view of this observation, we propose an interpolation based method that predicts pixels using predictors of different structure and order. Moreover, we use only original pixels for interpolation. Experimental results demonstrate that the proposed algorithm outperforms the state-of-the-art algorithms both in terms of embedding capacity and Peak Signal to Noise Ratio. © Springer International Publishing Switzerland 2015.

World University root node

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Adaptive predictor structure based interpolation for reversible data hiding

The paper presents a generalized understanding on the dynamics of the sliding variable for discrete time sliding mode control systems via a fresh approach involving several bands in the space of the sliding variable. Using this analysis, controller parameters can be obtained once the ultimate band is chosen. It is shown that on choosing the least ultimate band, the control becomes non-switching and Gao's reaching law becomes identical to Utkin's reaching law. On other occasions, the ultimate band obtained using this approach is clearly less than that obtained in previous works using Gao's reaching law. The analysis is presented for both state feedback and multirate output feedback cases. © 2014 Chinese Automatic Control Society and Wiley Publishing Asia Pty Ltd.

Asian Journal of Control

Minimum ultimate band design of discrete sliding mode control

A new family of continuous higher order sliding mode algorithm (CHOSMA) for arbitrary relative degree system via continuous control signal is proposed. The convergence conditions for the third order-CHOSMA algorithm is formulated based on homogeneous Lyapunov function. The formula for algorithm of arbitrary order is also suggested. The simulation results are confirmed the efficiency of the proposed algorithm. © 2015 IEEE.

2015 10th Asian Control Conference: Emerging Control Techniques for a Sustainable World, ASCC 2015

A new family of continuous higher order sliding mode algorithm

In an attempt to improve ON current and current ON/OFF ratio in tunnel field-effect Transistors (TFETs), a new wedge shaped structure for TFET named Wedge-TFET (WTFET) is proposed. This proposed device is a double gate structure, showing ∼3 times higher ON current compared to planar double gate TFET device working at supply voltage of 0.6 to 1.0 V. This increase is mainly due to increase in the tunneling area. In addition to increased current, W-TFET also shows high current ON/OFF ratio of the order ∼1012. The subthreshold swing values are slightly higher for W-TFET compared to our simulated DG-TFET, however, both of them fall in the range of 40 to 50 mV/dec. The W-TFET device with higher ON current and current ON/OFF ratio and with almost same area requirement can be a potential candidate for future low voltage applications. © 2015 IEEE.

IEEE-NANO 2015 - 15th International Conference on Nanotechnology

A wedge tunnel FET device for larger tunneling area and improved on current

A comprehensive study for crystal alignment of TIPS-Pentacene by an off-center spin coating has been presented. In a normal center spin coating method, the centrifugal force on the grains is multidirectional which results into crystals aligning in multiple directions depending on the location on the sample. However in an off-center spin coating method where the samples are kept at a distance away from the center, a unidirectional centrifugal force in the direction of the sample causes all the grains to align nearly in the direction of this force. The spin speed was the paramount factor influencing the overall grain size, whereas the overall alignment depends on the off-center distance. All the films in these experiments were found to have very large crystal sizes, ranging up to 5 microns. In addition, films formed by off-center method were found to be more crystalline than the center spin coated film and show a metastable crystalline polymorph. © 2015 IEEE.

Improved alignment and crystallinity of TIPS-Pentacene thin films by off-center spin coating

Ba0.5Sr0.5TiO3 (BST) thin films were deposited on sapphire substrate by RF magnetron sputtering techniques and interdigital capacitor (IDC) structures were fabricated using photolithography. Gamma irradiation induced changes of the BST based tunable capacitor have been investigated under various doses from 0 kGy to 600 kGy. Structural and surface morphological studies have been carried out for un-irradiated and irradiated film and revealed that the grain sizes and crystallinity are strongly depended on gamma irradiation doses. The leakage current is increased with increasing gamma irradiation doses due to creation of charge carriers and large numbers of defect in close proximity, provided path for charge carriers. The capacitance of the IDC devices decreased with increasing gamma dose up to 50 kGy and thereafter capacitance gradually increased with radiation doses and reached higher than the un-irradiated device at 600 kGy for 1 MHz frequency. The observed tunability (∼ 25) of the un-irradiated device was found nearly constant with gamma irradiation doses. This study shows that gamma ray induced defects play important role to the electrical properties of the devices and the BST based devices are highly resistant to gamma radiation, which reflects possible use in space and nuclear applications. © 2015 IEEE.

IEEE Transactions on Nuclear Science

Radiation Induced Response of Ba0.5Sr0.5 TiO3 Based Tunable Capacitors under Gamma Irradiation

This paper presents a novel capacitive shunt RF-MEMS switch. In the proposed design, broadside bridge structure joined with two cantilevers on either side has been used to implement the switch. The transmission line and actuation electrodes under the bridge are designed in the interdigitated form to reduce the area. Switch shows an insertion loss better than 0.11 dB, a return loss below 23.67 dB up to 25 GHz. In down-state, three resonant peaks of 34.71, 34.33 and 40.7 dB at 10.4, 11.0 and 21.4 GHz have been achieved as compared to a single peak in the case of the conventional switch. The proposed device has a bandwidth of 2.2 GHz in X-band and 5.2 GHz in K-band. Bridge structure shows a pull-in voltage of 12.25 V, actuation time of 34.40 µs while cantilevers have 7.5 V and 57 µs. Further, the electrical equivalent model has been presented to represent the switch. The model has been implemented in commercially available software. A good agreement with the 3-D electromagnetic simulated results validates the presented model. © 2015, Springer Science+Business Media New York.

Wireless Personal Communications

A Novel Approach for Low Insertion Loss, Multi-band, Capacitive Shunt RF–MEMS Switch

This paper presents a new type of capacitive shunt RF-MEMS switch. In the proposed design, float metal concept has been utilized to make the asymmetric structure on either side of the transmission line to implement the switch. This novel structure is used to inductively tune the isolation in C, X and Ku bands. Isolation peaks of 42.63, 44.22 and 47.75 dB has been observed at 7.2, 8.8 and 16.5 GHz when left, right or both cantilevers are electro-statically actuated in the down-state respectively, whereas conventional switch has peak only in X-band. Switch shows an insertion loss better than 0.10 dB, a return loss below 23.93 dB up to 25 GHz as compared to 0.90 dB insertion loss and 8.02 dB of return loss in case of conventional device. Further, improvement of around 5 times in bandwidth, 50 % in the pull-in voltage and 16.7 % in device area have also been observed. The designed switch can be useful at device and sub-system level for the future multi-band communication applications. © 2014, Springer-Verlag Berlin Heidelberg.

Microsystem Technologies

Performance improvement of RF-MEMS capacitive switch via asymmetric structure design

This paper presents a new single pole double throw (SPDT) RF MEMS switch design based on a torsional series capacitive switch. The torsional configuration and use of floating metal reduce the stiction probabilities. Use of a single series capacitive switch compared to the conventional approach of a capacitive and series combination, offers compact size, higher bandwidth and superior reliability. The optimized SPDT topology offers a wider bandwidth of 17 GHz (3–20 GHz) with insertion loss of −0.3 to −0.4 dB and isolation −20 to −44 dB. The proposed structure actuates at 9 V and the contact force varies in the elastic contact regime from 20 to 68 µN for the bias voltage of 10–15 V. © 2014, Springer-Verlag Berlin Heidelberg.

Design of compact and wide bandwidth SPDT with anti-stiction torsional RF MEMS series capacitive switch

An analog phase shifter based on distributed MEMS transmission line (DMTL) is designed for Ku band applications. Traditional RF MEMS phase shifter comprising 6 switches has limited phase shift of 37.75° due to instability region. A new concept of stopper is incorporated to achieve high phase shift. In the present paper, optimisation of the analog phase shifter is done to increase its phase shift upto 88.63°. Phase shift is a strong function of capacitance ratio which is increased from 1.75 to 2.95. The maximum operating voltage and mechanical resonant frequency for the phase shifter are 16 V and 8.3 KHz, respectively. The switching time is calculated to 56 μs. The simulated insertion loss of the phase shifter is -1.75 dB with return loss of -20.49 dB at 17 GHz. The simulated results are verified with analytical modelling which are in close match. © 2015, DESIDOC.