Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In this study, analysis of extending the linear modulation range of a zero common-mode voltage (CMV) operated n-level inverter by allowing reduced CMV switching is presented. A new hybrid seven-level inverter topology with a single DC supply is also presented in this study and inverter operation for zero and reduced CMV is analysed. Each phase of the inverter is realised by cascading two three-level flying capacitor inverters with a half-bridge module in between. Proposed inverter topology is operated with zero CMV for modulation index <86% and is operated with a CMV magnitude of Vdc/18 to extend the modulation range up to 96%. Experimental results are presented for zero CMV operation and for reduced common voltage operation to extend the linear modulation range. A capacitor voltage balancing algorithm is designed utilising the pole voltage redundancies of the inverter, which works for every sampling instant to correct the capacitor voltage irrespective of load power factor and modulation index. The capacitor voltage balancing algorithm is tested for different modulation indices and for various transient conditions, to validate the proposed topology.

Department of Electrical Engineering

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IET Power Electronics

Reduced common-mode voltage operation of a new seven-level hybrid multilevel inverter topology with a single DC voltage source

Zero-common-mode-voltage (CMV) operation of multilevel inverters results in reduced dc-bus utilization and reduced linear modulation range. In this paper, a method to increase the linear modulation range for zero-CMV operation without increasing the dc-bus voltage using a cascaded multilevel inverter with a single dc supply is presented. Using this method, the peak fundamental output voltage can be increased from 0.499 to 0.637 V dc with zero CMV inside the linear modulation range. Also, various pulse width modulation (PWM) switching sequences are analyzed in this paper and the PWM sequence that gives minimum current ripple is used for the zero-CMV operation of the inverter. The inverter topology with single dc supply is realized by cascading a two-level inverter with two floating-capacitor-fed full-bridge modules. Simulation and experimental results for steady-state and dynamic operating conditions are presented to validate the proposed method.

IEEE Transactions on Industrial Electronics

Extended Linear Modulation Operation of a Common-Mode-Voltage-Eliminated Cascaded Multilevel Inverter with a Single DC Supply

A systematic measurement procedure of high isolation single-pole-double-throw (SPDT) switch utilizing six metal contact switches using micro electromechanical systems (MEMS) is presented in this paper. A complete measurement procedure of a MEMS DC-contact is outlined here including profile analysis, mechanical, electrical, switching/release time, temperature stability, power handling, intermodulation, IIP3, S-parameter and reliability. Measured return loss of better than 20 dB with worst case insertion loss of 1.67 dB and isolation greater than 42 dB have been experimentally obtained from the SPDT switch up to 20 GHz within 1.25 mm2 area. Switch demonstrates temperature stability up to 70°C temperature and 0.1-1 W of RF power handling. © 2016 Wiley Periodicals, Inc.

Microwave and Optical Technology Letters

Systematic measurements of high isolation DC - 20 GHz miniature MEMS SPDT switch

We describe the optical properties of nonvolatile memory cells based on metal-insulator-semiconductor structures with embedded Pt nanoparticles, fabricated by atomic layer deposition. We show the effect of illumination on the static as well as dynamic properties of two devices, which differ by their respective thicknesses of the tunneling layer. The device with the thicker tunneling layer exhibits a faster response under illumination and significantly better retention properties, while the device with the thinner tunneling layer is faster under dark conditions. © 2002-2012 IEEE.

IEEE Transactions on Nanotechnology

Dynamical properties of optically sensitive metal-insulator-semiconductor nonvolatile memories based on Pt Nanoparticles

We report a strong negative capacitance effect in back to back combination of a metal-insulator-semiconductor (MIS) structure and a metal-semiconductor junction, which is fabricated on an n type Silicon-on-Insulator substrate. The MIS capacitor comprises a SiO2-HfO2 insulator stack with embedded Pt nanoparticles. The capacitor undergoes a voltage stress process and thereby turns into a varactor and a photodetector. The negative capacitance is observed only under illumination in structures that employ a Schottky back contact. A symmetric double or an asymmetric single negative capacitance peak is observed depending on the nature of illumination. The phenomenon is attributed to the modulation of the semiconductor conductance due to photo generated carriers and their incorporation in trapping/de-trapping processes on interfacial and post filamentation induced defects in the insulator stack. The frequency range of the observed effect is limited to 100 kHz. Large ratios of light to dark and maximum to minimum of negative capacitances as well as of the obtained sensitivity to the applied voltage are, respectively, 105, more than 100, and 10-15. These were measured at 10 kHz under illumination at 365 nm with a power of 2.5 × 10-6 W. © 2016 Author(s).

Journal of Applied Physics

Negative capacitance in optically sensitive metal-insulator-semiconductor-metal structures

A new Resistance-to-Digital Converter (RDC) suitable for single element resistive sensors is presented in this paper. The proposed scheme is based on a relaxation oscillator circuit, which along with a timer-counter that measures the time intervals of oscillations, provides digital output proportional to the resistance of the sensor. In most of the existing RDCs, the output characteristic has gain, offset and non-linearity errors owing to various circuit parameters and their drift in the measurement unit. The output of the proposed RDC has a special nature, by the design of the measurement method, that it is not a function of the circuit parameters such as offset voltages and bias currents of the opamps and comparators used, gain of various units employed, ON-resistance of the switches, value or mismatch in the magnitudes of the reference voltages employed, etc. Such a scheme will be useful for high accuracy measurements, even in circumstances where the above-mentioned parameters may vary or drift, due to variation in the measurement environment, say, large variation in temperature. A prototype of the proposed RDC has been developed in the laboratory and the performance has been tested under various conditions. The output was found to be linear with a worst-case non-linearity of 0.06 % As expected, the sensitive of the output of the prototype RDC to various circuit parameters was found to be negligible. © 2016 IEEE.

Conference Record - IEEE Instrumentation and Measurement Technology Conference

A Resistance-to-Digital Converter possessing exceptional insensitivity to circuit parameters

In this paper, we present the modeling and local equilibrium controllability analysis of a spherical robot. The robot consists of a spherical shell that is internally actuated by a pendulum mechanism. The rolling motion of the sphere manifests itself as a nonholonomic constraint in the modeling. We derive the dynamic model of the system using Lagrangian reduction and the variational principle. We first compute the Lagrangian and identify the symmetry with respect to a group action. The system Lagrangian and the rolling constraint are invariant with respect to the group isotropy and hence permit a reduced dynamic formulation termed as the nonholonomic 'Euler-Poincaré' equation with advected dynamics. Using Lie brackets and symmetric products of the potential and control vector fields, local configuration accessibility and local (fiber) equilibrium controllability are presented. © 2015 John Wiley & Sons, Ltd.

International Journal of Robust and Nonlinear Control

Geometric modeling and local controllability of a spherical mobile robot actuated by an internal pendulum

Metal-insulator-metal capacitors for dynamic random access memory applications have been realized using TiO2/ZrO2/TiO2 (TZT) and AlO-doped TZT [TiO2/ZrO2/AlO/ ZrO2/TiO2 (TZAZT) and TiO2/ZrO2/AlO/ZrO2/AlO/ZrO2/TiO2 (TZAZAZT)] dielectric stacks. High-capacitance densities of 46.6 fF/μm2 (for TZT stacks), 46.2 fF/μm2 (for TZAZT stacks), and 46.8 fF/μm2 (for TZAZAZT stacks) have been achieved. Low leakage current densities of about 4.9 × 10-8, 5.5 × 10-9, and 9.7 × 10-9 A/cm2 (at -1 V) have been obtained for TZT, TZAZT, and TZAZAZT stacks, respectively. We analyze the leakage current mechanisms at different electric field regimes, and compute the trap levels. The effects of constant voltage stress on the device characteristics were studied, and excellent device reliability was demonstrated. The electrical characteristics of the devices were correlated with the structural analysis through X-ray diffraction measurements and the surface chemical states analysis through X-ray photoelectron spectroscopy measurements. The doped-dielectric stacks (AlO-doped TZT: TZAZT and TZAZAZT) help to reduce leakage current density and improve reliability, without substantial reduction in capacitance density, compared with their undoped counterparts (TZT). © 1963-2012 IEEE.

IEEE Transactions on Electron Devices

Performance and Reliability of TiO2/ZrO2/TiO2 (TZT) and AlO-Doped TZT MIM Capacitors

The focus of this work is to study the effect of cobalt (Co) and Mg doping on structural, surface morphological, photocatalytic, antibacterial and magnetic properties of ZnO nanopowders. The undoped and doped ZnO nanopowders were prepared using a simple, speedy and cost-effective microwave assisted synthesis. The XRD studies reveal that the Co doping only slightly degrade the crystalline quality of ZnO nanopowder whereas Mg doping causes a considerable degradation in the crystallinity. This result is interpreted on the basis of lattice compatibility theory. Surface morphological study shows that ZnO nanopowder exhibits hexagonal shaped grains. The Co doping results in well defined needle and disc shaped grains while spherical shaped ZnO nanopowders are observed for Mg doped ZnO nanopowders. The EDAX spectra affirm the presence of anticipated elements Zn, O, Co and Mg. The Co doping induces room temperature ferromagnetism in ZnO nanopowders. Both the dopants enhance the photocatalytic activity against methylene blue dye and antibacterial activities against gram negative bacteria such as E. coli and Vibrio cholerae. Between the Co and Mg doped ZnO nanopowders, the former seems to be superior in photocatalytic and antibacterial activities.

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS

Enhanced photocatalytic, antibacterial and magnetic properties of ZnO nanopowders through lattice compatible cobalt doping

Automatic detection and removal of baseline wanders is most important for accurate measurement of clinical features of local waves including, P-wave, QRS complex, T-wave and U-wave of the ECG signals. In this paper, we investigate on the use of variational mode decomposition (VMD) technique for removal of baseline wander in ECG signals. The proposed method consists of three stages: VMD based ECG signal decomposition, baseline wander extraction using frequency criterion, and base-line wander subtraction. The method is tested and evaluated using a wide variety of ECG signals including different kinds of PQRST morphologies corrupted with different patterns of baseline wanders. Performance evaluation results show that the VMD based method can adequately remove the baseline wanders without significantly distorting local components (P-wave, QRS complex, ST-segment, T-wave) of the ECG signal. The noise reduction capability of the VMD-based method is compared with the existing methods using the wavelet transform and Fourier transform. The subjective and objective quality assessment results show that the VMD based method outperforms the existing methods in terms achieving better objective quality metric values for various noisy ECG signals. © 2016 IEEE.