Department of Electrical Engineering

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

A common way to analyze electrostatic microelectromechanical systems (MEMS) actuators is to use their energy-displacement landscape. Here, we describe an alternative approach to analyze electrostatic MEMS actuators using their energy-charge landscape. This technique involves coordinate transformation from displacement to charge, thereby formulating the Hamiltonian of electrostatic MEMS actuators in terms of charge. We investigate the use of the energy-charge landscape to analyze static pull-in, dynamic pull-in, and pull-out phenomena. The voltage expressions derived using this method are identical with those derived using the conventional energy-displacement landscape. In addition, we also obtain the expressions for charge under static and dynamic pull-in conditions. This work can aid in the design and analysis of electrostatic MEMS devices. As a case study, the analysis of a feedback capacitor-MEMS actuator system is presented to illustrate the application of the energy-charge landscape. © 1963-2012 IEEE.

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IEEE Transactions on Electron Devices

Analysis of Electrostatic MEMS Using Energy-Charge Landscape

Ultrasound medical imaging systems typically follow standard delay and sum (DAS) beamforming at the reception for image reconstruction. In DAS, the echo signals that are returned to the transducer are aligned in time and summed to form the beamformed signal. To improve the image quality and the signal to noise ratio of DAS, a non-linear beamforming named delay multiply and sum (DMAS) has been proposed in the literature, where, the signals arriving at the transducer are aligned in time and are pairwise multiplied in all possible combinations before summation. This provides better coherence, a correlation-based data-driven apodization, and consequently result in better contrast and resolution. However, the computational complexity of DMAS is higher than DAS thus restricting its real-time implementation. This paper presents two novel VLSI architectures for the implementation of DMAS, whose complexity is independent of the number of transducer elements. The proposed architectures are implemented on xc7z010c1g400-1 FPGA and the results clearly show the channel independency of the proposed architectures. © 2020 IEEE.

SPCOM 2020 - International Conference on Signal Processing and Communications

VLSI architectures for Delay Multiply and Sum Beamforming in Ultrasound Medical Imaging

Musculoskeletal (MSK) ultrasound imaging aims to provide pictures of tissues and bones such as muscles, tendons, ligaments, joints and soft tissues throughout the body. One of the major landmarks in MSK ultrasound are the bones, and segmentation of bone surface has numerous applications in computer-aided orthopedic diagnosis. In this work, a novel method of bone aware image enhancement of MSK ultrasound images is presented. A combination of fundamental and harmonic US images is used for bone segmentation. The method for bone segmentation takes into account the acoustic characteristics of the intensity of bones used for computing their acoustic shadows, local phase-based features such as local energy, local phase, and feature symmetry based on a reported work in literature. It is combined with integrated backscattering of the bone to provide a probability map of the bone. Bone location in probability map was found based on the centroid of the intensity distribution. Further, image enhancement of the extracted region of interest based on the bone for distinctive visualization of the muscular and tendon region above the bone structure is presented. The image enhancement techniques employed are gamma correction, histogram equalization, adaptive histogram equalization and an improved frequency based super-resolution of ultrasound images. © 2020 IEEE.

IEEE Region 10 Annual International Conference, Proceedings/TENCON

Towards bone aware image enhancement in musculoskeletal ultrasound imaging

A five level inverter topology with single DC supply is analysed for an open end winding induction motor (OEWIM) drive. A carrier based modulation scheme is proposed to eliminate the common mode (CMV) and differential mode voltages (DMV). The modulation scheme utilises the voltage vector and switching state redundancy of the inverter topology. The voltage vector redundancy is used to eliminate the DMV and switching state redundancy is used to eliminate the CMV. Compared to the conventional level shifted PWM method, the proposed modulation scheme offers improved harmonic performance and also ensures self-balancing of capacitor voltages. The simulation studies are carried out in MATLAB for an OEWIM drive operating with open-loop constant Volts-per-Hertz control. The modulation scheme is implemented using TMS320F28379D controller board and an FPGA module. © 2020 EPE Association.

2020 22nd European Conference on Power Electronics and Applications, EPE 2020 ECCE Europe

Modulation scheme with common mode and differential mode voltage elimination for a five level inverter fed open end winding induction motor drive

Detection of a weak signal in additive Generalized Cauchy (GC) noise is important in many applications. The locally optimum detector (LOD) for a weak signal in GC noise is nonlinear in nature. When noise variance is unknown, the maximum likelihood estimator (MLE) is nonlinear and the resultant detector is complicated. Since VLSI implementation of complex nonlinearities is a challenging task, we develop an order statistics framework for detection in GC noise. We propose linear and ratio detectors, for weak signals in GC noise with known and unknown but deterministic variance, respectively. We provide extensive simulation results to show that performance loss of proposed linear and ratio detectors, is very small compared to LOD and nonlinear detector using MLE, respectively. We propose SORT - N (for running ordering of samples) and its VLSI architecture, using which we develop two-stage VLSI architectures for proposed linear and ratio detectors. Synthesis results for arbitrary waveform case indicate, for same throughput and latency, linear detector consumes lesser area to LOD, upto a sample size of N=64. For same throughput, ratio detector renders substantial area savings (≈50%) over nonlinear detector using MLE, for any N. Finally, we propose a reconfigurable architecture for efficient realization of all the detectors. © 2004-2012 IEEE.

IEEE Transactions on Circuits and Systems I: Regular Papers

Area Efficient VLSI Architectures for Weak Signal Detection in Additive Generalized Cauchy Noise

Electrochemical metallization (ECM)-based resistive switching devices with very small inter-electrode distances have recently been reported. These devices have very low switching voltages (sub-1V), fast switching times and low switching energies. Ab-initio simulations predict low device failure for these devices. In this work, we model the dynamic characteristics of ECM-based memristors (implemented in Verilog-A), with a focus on simulating the switching delays during SET and RESET processes and calculating the energy consumption during switching. We have compared the simulation results obtained using our model, with experimental data available in literature. © 2020 IEEE.

2020 5th IEEE International Conference on Emerging Electronics, ICEE 2020

Modeling the dynamics of switching in electrochemical metallization (ECM)-based memristors

In the last few years, there has been extensive research in the design and fabrication of tandem solar cells. To analyse the transport in these devices and to optimize the device structure for enhanced response, simulation of these device configurations are crucial. In our work, we simulate the optoelectronic behaviour of a perovskite-silicon multi-junction tandem solar cell with a silicon tunnel junction, by accounting for different optical losses at the interface of each layer and by taking into account the limits of different recombination mechanisms (radiative and non-radiative). We have used a simple TCAD-based approach to understand and model the different transport mechanisms and losses in a perovskite-silicon tandem solar cell. We have compared simulated characteristics with corresponding measured characteristics from an experimental device. © 2020 IEEE.

Modeling of Perovskite-Silicon Tandem Solar Cells: A TCAD-based Approach

Transition metal dichalcogenide (TMD) memris-tors with vertical transport and atomic scale inter-electrode distances have recently been reported. These devices demonstrate bipolar switching characteristics, with relatively low switching voltages. With multiple input sweeps, variability in switching behaviour is also seen. Our work models the transport in vertical TMD memristors, with a focus on explaining the current-voltage (I-V) characteristics and the associated variability, by analysing different current components. © 2020 IEEE.

Proceedings of the IEEE Conference on Nanotechnology

Modeling of electrochemical metallization-based transport in vertical transition metal dichalcogenide (TMD) memristors

This paper presents a novel linear to cross reflective type polarization converter for X and Ku-band applications. It comprises a 45° tilted resonating patch on the top of a thin FR-4 substrate, which is terminated by PEC on the other side. The converter exhibits Polarization Conversion Ratio (PCR) greater than 90% over 10.17 GHz bandwidth (from 8.2 to 18.37 GHz ) with 76.5% fractional bandwidth (FBW). Multiple surface plasmonic resonances are responsible for uniform PCR over the broadband. The reason behind the ideal response at resonant frequencies is illustrated by surface current distribution analysis. This design is obliquely stable up to 30°, with a minimum of 87% PCR, for the transverse electric (TE) mode and the same is observed for transverse magnetic (TM) case. The proposed linear-cross converter is compact with periodicity 0.213λL and thickness 0.07λL, where λL corresponding to the free-space wavelength of lowest bandwidth frequency. RCS analysis has been performed for monostatic and bistatic cases to demonstrate the capability of the proposed design in EM shielding applications. © 2020 IEEE.

Proceedings of the 2020 International Symposium on Antennas and Propagation, APSYM 2020

Broadband Linear-Cross Reflective type Polarization Converter for X and Ku-band Applications

This work presents a single-layered broadband polarization-insensitive circuit analog absorber for X to K-band applications. The design is made of a circular ring resonator loaded with four lumped resistors and a circular-split cross dipole, printed on the top of a dielectric substrate terminated with the ground. In the azimuthal plane, the proposed structure is insensitive to different polarization angles of the electric field due to the four-fold symmetry, and it also demonstrates a stable absorptivity up to 45° for both Transverse Electric (TE) and Transverse Magnetic (TM) incidences in the elevation plane. Multiple plasmonic resonances are responsible for the broadband behaviour, and the ohmic losses in lumped elements are the reason for near-unity absorption over the broadband. The response of the proposed equivalent transmission line model is validated with the full-wave analysis up to a reasonable extent. To the best of authors knowledge, this design is angular stable absorbing metasurface operational with limited chip resistors over broadband without compromising the performances, and it is suitable for the applications like Radar Cross Section (RCS) reduction and RF energy harvesting. © 2020 IEEE.