Faculty Publications

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Publications by NITK Faculty

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0.5 V, 36Î¼W Gm-C butterworth low pass filter in 0.18Î¼m CMOS process
(2012) Vasantha, M.H.; Laxminidhi, T.
This paper presents a low voltage, low power continuous-time (G m-C) 4th order low pass Butterworth filter with a 3-dB bandwidth of 1MHz and capable of operating at supply voltage as low as 0.5V in 0.18 Î¼m. The filter uses bulk-driven technique for achieving the necessary head-room. The simulation results show that the filter has a peak-to-peak signal swing of 1.2V (differential) for 1% THD and a dynamic range of 54 dB. The power consumed by the filter is 36Î¼W when operating at a voltage of 0.5 V. The Figure of Merit (FOM) achieved by the filter is 0.05 fJ and is found to be lowest among the similar filters found in the literature. Â© 2012 IEEE.
0.5 V, low power, 1 MHz low pass filter in 0.18 Î¼m CMOS process
(2012) Vasantha, M.H.; Laxminidhi, T.
In this paper a low power continuous-time 4th order low pass Butterworth filter operating at power supply of 0.5 V is presented. A 3-dB bandwidth of 1 MHz using technology node of 0.18 Î¼m is achieved. In order to achievenecessary head-room, the filter uses pseudo-differential bulk-driven transconductor. A master-slave based common modefeedback(CMFB) circuit sets the output common mode voltageof transconductor. The simulation results show that the filter has a dynamic range of 54 dB and consumes a total power of 36 Î¼W when operating at a supply voltage of 0.5 V. The Figure of Merit (FOM) achieved by the filter is 0.05 fJ, lowest among similar low-voltage filters found in the literature. The simulation result show that the 3-dB bandwidth variation for process, voltage and temperature is less than Â±10%. Â© 2012 IEEE.
1 V, 20 nW True RMS to DC Converter based on Third Order Dynamic Translinear Loop
(Taylor and Francis Ltd., 2023) Mansoor, C.B.; Patii, A.; Rekha, S.
This paper presents a novel current-mode true RMS–DC converter based on the dynamic translinear principle. The converter is designed using a third-order translinear loop, resulting in a very compact and simple circuit. The proposed circuit is designed in 65 nm CMOS technology, operates with 1 V power supply, has only 14 transistors and performs satisfactorily over a wide input current range of 300 nA–950 nA and for a frequency range of 600 Hz–650 kHz for a capacitance value of 10 nF. The frequency range of operation can be tuned by varying the external off chip capacitor and the bias current. The circuit consumes 20 nW static power, 1.6 μW maximum dynamic power and offers the lowest FOM among the other RMS–DC converter circuits presented in the literature. Comprehensive mathematical analysis along with the post layout simulation results confirm the validity of the proposed circuit. To test the use of converter in real world scenarios, the proposed converter is introduced within a typical ECG detection system and the results show that the circuit is an attractive solution for RMS–DC conversion in low-voltage low-power applications. © 2023 IETE.
1,3,4-Trisubstituted pyrazole bearing a 4-(chromen-2-one) thiazole: Synthesis, characterization and its biological studies
(Royal Society of Chemistry, 2015) Harikrishna, N.; Isloor, A.M.; Kulal, K.; AlObaid, A.; Fun, H.-K.
A new series 3-{2-[N?-(1,3-disubstituted-1H-pyrazol-4-yl-methylene)-hydrazino]-thiazol-4-yl}-chromen-2-one (10a-l) was synthesized by a multi-step reaction. All the synthesized compounds were characterized by IR, NMR, and mass spectral studies, followed by elemental analysis. The newly synthesized thiazole compounds were screened for their in vitro antibacterial and antifungal studies against various microorganisms. Antimicrobial studies carried out by the well diffusion method, showed a very good zone of inhibition for both bacteria (at a range of 20-50 mm diameter) and fungi (at a range of 10-30 mm diameter). Minimum Inhibitory Concentration (MIC) required for the 100% inhibition of bacteria and fungi was found to be as low as 15.6 ?g ml-1 for a few of the synthesized compounds. © The Royal Society of Chemistry 2015.
1,5-Dibromo-2,4-dimethoxybenzene
(2012) Vijesh, A.M.; Isloor, A.M.; Gerber, T.; Brecht, B.V.; Betz, R.
In the title compound, C8H8Br2O2, all non-H atoms lie essentially in a common plane (r.m.s deviation of all fitted non-H atoms = 0.0330 Å). In the crystal, weak C-H?O hydrogen bonds connect the molecules, forming chains which extend along the b-axis direction.
1-(4-Bromophenyl)-2-(2-chlorophenoxy)ethanone
(2012) Shenvi, S.S.; Isloor, A.M.; Gerber, T.; Hosten, E.; Betz, R.
In the title compound, C14H10BrClO2, a twofold halogenated derivative of phenylated phenyloxyethanone, the least-squares planes defined by the C atoms of the aromatic rings subtend an angle of 71.31 (17)°. In the crystal, C-H?O contacts connect the molecules into chains along the b-axis direction.
1-[(3-Benz-yloxy-2-nitro-phen-oxy)meth-yl]benzene
(2012) Fun, H.-K.; Arshad, S.; Ubaradka, S.R.; Shetty, P.; Isloor, A.M.
The asymmetric unit of the title compound, C20H17NO4, consists of two crystallographically independent mol-ecules. In one of the mol-ecules, the central benzene ring forms dihedral angles of 2.26 (6) and 58.68 (6)°with the terminal benzene rings and the dihedral angle between the terminal benzene rings is 56.45 (6)°. The corresponding values for the other mol-ecule are 35.17 (6), 70.97 (6) and 69.62 (6)°, respectively. In the crystal, an inversion dimer linked by a pair of C-H?O hydrogen bonds occurs for one of the unique mol-ecules. C-H?? and ?-? [centroid-centroid distances = 3.7113 (8) and 3.7216 (7) Å] inter-actions link the components into a three-dimensional network.
1-[5-Acetyl-2,6-dimethyl-4-(5-phenyl-1H-pyrazol-3-yl)-1, 4-dihydropyridin-3-yl]ethanone monohydrate
(2012) Islor, A.M.; Malladi, S.; Sundershan, S.; Gerber, T.; Hosten, E.; Betz, R.
In the title compound, C20H21N3O 2·H2O, the aza-substitued six-membered ring adopts a L4 B conformation. In the crystal, classical N-H?O, N-H?N and O-H?O hydrogen bonds connect the entities into a three-dimensional network. Intramolecular C-H?O contacts are also observed.
1-Cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4-carboxy-lic acid
(2011) Fun, H.-K.; Ching Kheng, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.
In the title compound, C17H20N2O 3, the meth-oxy-phenyl unit is disordered over two sets of sites in a 0.715 (4):0.285 (4) ratio. The pyrazole ring forms dihedral angles of 55.88 (16) and 72.6 (4)°with the benzene rings of its major and minor components, respectively. The cyclohexane ring adopts a chair conformation and its C-N bond is in an equatorial orientation. In the crystal, molecules are linked into inversion dimers by pairs of O-H?O hydrogen bonds, generating R 2 2(8) loops..
1-D CNN for Mineral Classification using Hyperspectral Data
(Institute of Electrical and Electronics Engineers Inc., 2023) Yadav, P.P.; Shetty, A.; Raghavendra, B.S.; Narasimhadhan, A.V.
Hyperspectral Image (HSI) is a potent remote sensing (RS) technique, capturing images over numerous narrow, contiguous spectral bands. Unlike traditional RS methods, HSI offers detailed spectral insights for each pixel, enhancing comprehension of the Earth's surface and its contents. Initially intended for mining and geology, its application has expanded across various domains. Yet, mineral identification poses challenges due to spectral signature variations and limited ground truth. Despite various advanced algorithms, including machine learning, no dedicated Deep Learning (DL) expert system exists for mineral classification in HSI. DL models require abundant training data and ground-truth, which are scarce in hyperspectral mineral data. Introducing the 1-D CNN model as a proposed method, we focus on enhancing mineral classification by increasing the available training data. The utilization of augmented training samples through the 1-D CNN model tackles the challenge of limited ground truth data, enabling accurate classification of mineral classes. Â© 2023 IEEE.
1-Dibromomethyl-4-methoxy-2-nitrobenzene
(2009) Fun, H.-K.; Goh, J.H.; Chandrakantha, B.; Isloor, A.M.
The asymmetric unit of the title compound, C8H 7Br2NO3, comprises two crystallographically independent molecules (A and B). The nitro groups are twisted from the attached benzene rings, making dihedral angles of 39.26 (9) and 35.90 (9)° in molecules A and B, respectively. In each mol-ecule, the dibromo-methyl group is orientated in such a way that the two Br atoms are tilted away from the benzene ring. An inter-esting features of the crystal structure is the two short Br?Br inter-actions which, together with inter-molecular C - H?O hydrogen bonds, link the molecules into an extended three-dimensional network. The crystal structure is further stabilized by weak C - H?? inter-actions. © Fun et al. 2009.
1-Hexyl-3-Methylimidazolium Chloride-Potassium Carbonate Aqueous Two Phase System: Equilibrium Characteristics and BSA Partitioning Behavior
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2014) Iyyaswami, I.; Monteiro, S.L.
The partitioning behavior of the model protein (bovine serum albumin) was investigated in ionic liquid (1-hexyl-3-methylimidazolium chloride) -salt (potassium carbonate) based aqueous two phase system (ATPS). The phase diagram with binodal curve and tie lines for the selected ATPS was developed at different temperatures and analyzed through effective excluded volume (EEV) and Othmer-Tobias and Bancroft equations, respectively. The influence of various process parameters like the ionic liquid and salt concentration, system temperature, tie line length, phase volume ratio, and neutral salt addition on partition coefficient/extraction efficiency of BSA protein was evaluated. © 2014 Copyright Taylor & Francis Group, LLC.
1.5Â°C accurate CMOS temperature sensor with a single point trim at 85Â°C
(Institute of Electrical and Electronics Engineers Inc., 2016) Hareesh, P.K.; Laxmindhi, T.
This paper presents a temperature sensor with an accuracy of 1.5Â°C. The paper analyzes inaccuracy of the existing temperature sensors and outlines the techinques to overcome them. The sensor is based on a CMOS current reference which is almost constant over process/corner and voltage variation. Most of the techniques known today for generating a process and voltage independent current source have very stringent constraints on sizing of the transistors. The current source proposed in the paper relaxes such constraints thus easing the portability across various technology nodes. The sensor designed in TSMC 28 nm CMOS process offers the accuracy of 1.5Â°C over a temperature range of-40Â°C to 125Â°C with a single point trim at 85Â°C. The sensor consumes a power of 90 Î¼W of power when operating on 1.8 V supply. Â© 2016 IEEE.
1.8 V, 25.9 nW, 91.86 dB dynamic range second-order lowpass filter tunable in the range 4-100 Hz
(Institution of Engineering and Technology kvukmirovic@theiet.org, 2019) Reddy, J.R.M.K.; Laxminidhi, T.
A second-order lowpass Butterworth filter with tunable bandwidth capable of offering a dynamic range of 91.86 dB operating on a supply voltage of 1.8 V is presented. The proposed filter is based on a sub-threshold source follower. The transistor bias currents are switched to enable the bandwidth tuning in the range 4-100 Hz. A proportional to absolute temperature (PTAT) current reference circuit helps to keep the bandwidth intact across process, voltage and temperature variations. The filter, designed in 0.18 ?m standard CMOS process, consumes 25.9 nW making it a potential candidate for portable biomedical applications. © The Institution of Engineering and Technology 2019.
11.39 fJ/conversion-step 780 kS/s 8 bit switched capacitor-based area and energyefficient successive approximation register ADC in 90 nm complementary metal-oxide- semiconductor
(Institution of Engineering and Technology journals@theiet.org, 2018) Narasimaiah, J.D.; Laxminidhi, T.; Bhat, M.S.
In this study, a design technique for low-energy consumption and area-efficient successive approximation register analogue-to-digital converter (ADC) is presented. Digital-to-analogue conversion equivalent voltage is acquired utilising passive sharing of charge between two unit capacitors and integration of the shared charge onto an input sample-and-hold capacitor, via a switched capacitor integrator circuit. The architecture is less parasitic sensitive and low noise, yielding an area and energyefficient ADC. To demonstrate the efficacy of the proposed technique, a ±350 mV 8 bit 0.78 MS/s ADC is designed in a 90 nm complementary metal-oxide-semiconductor process. The ADC core has a small area footprint of 0.00145 mm2 and has a figure-of-merit of 11.39 fJ/conv-step. © 2018, The Institution of Engineering and Technology.
14.5 fJ/conversion-step 9-bit 100-kS/s nonbinary weighted dual capacitor array based area and energy efficient SAR ADC in 90 nm CMOS
(Institution of Engineering and Technology journals@theiet.org, 2018) Narasimaiah, J.D.; Bhat, M.S.
In this work, design technique and analysis of low-energy consumption successive approximation register (SAR) analogue-to-digital converter (ADC) is presented. A dual capacitor array (CA) generates a digital-to-analogue reference voltage with increased accuracy. The CA supports multiple parallel operations to enhance conversion speed. Unit sized capacitors in CAs are few in number and present good capacitance density, thereby providing area efficiency and ease of routeing. A 9-bit SAR ADC using the proposed dual CA, implemented in a 90 nm CMOS process, has a small core area footprint of 0.00371 mm2. At a 1 V supply and 100 kS/s, the ADC achieves a signal-to-noise and distortion ratio of 53.55 dB and consumes 0.47 ?W, resulting in a figure-of-merit of 14.5 fJ/conversion step. © The Institution of Engineering and Technology 2018.
1D convolutional neural networks-based soil fertility classification and fertilizer prescription
(Elsevier B.V., 2023) Sujatha, M.; Jaidhar, C.D.; Lingappa, M.
Sustainable agriculture is essential to meet the demands of the global population. An adequate application of fertilizers is essential for sustainable agricultural productivity. This research aims to determine soil fertility and provide precise fertilizer to improve crop yield. Many researchers have proposed soil fertility classification using deep learning-based approaches, such as extreme learning machines (ELMs) and multilayer perceptrons (MLPs). Although both ELM and MLP have the highest performance, insufficient training data prevent them from being useful. To address this limitation, this research proposes a 1D convolution neural networks (1D-CNN)-based soil fertility classification method that is straightforward, compact, and supports scalar additions and multiplications. To classify soil fertility, the classifier employs laboratory-measured soil data that encompasses electrical conductivity, pH, organic carbon, potassium, phosphorus, sulfur, boron, copper, iron, manganese, and zinc. The proposed approach employs MinMax normalization and the synthetic minority oversampling technique (SMOTE) to improve the classifier performance. The results of soil classification are used to recommend fertilizers. An experimental study using a laboratory-measured soil dataset showed that the proposed technique outperformed ELM and MLP classifiers. The proposed approach outperformed ELM and MLP with a classification accuracy of 97.9%, while ELM and MLP achieved classification accuracies of 69.80% and 87.06%, respectively. The proposed method can help farmers manage soil fertility sustainably to increase crop production. © 2023 Elsevier B.V.
(1Z)-1-(2,4-Dichloro-phen-yl)ethan-1-one semicarbazone
(2009) Fun, H.-K.; Balasubramani, K.; Vijesh, A.M.; Malladii, S.; Isloor, A.M.
In the title compound, C9H9Cl2N 3O, the semicarbazone group is approximately planar, with an r.m.s deviation from the mean plane of 0.011 (2) Å. The dihedral angle between the least-squares planes through the semicarbazone group and the benzene ring is 38.76 (9)°. The crystal structure is further stabilized by N - H?O and C - H?O hydrogen bonding. © Fun et al. 2009.
(2,1)-Lagged fibonacci generators using elliptic curves over finite fields
(2009) Shankar, B.R.; Karuna Kamath, K.
A novel pseudorandom sequence generator is presented in this paper. The genesis of this new generator is evolved from the concept of Lagged Fibonacci generator[1] applied to points on elliptic curves over a finite field. It is observed that the generator has a long period. Also a successful statistical testing of the randomness attributes of the given generator, in accordance with the National Institute of Standards and Technology test suite, admits to a key stream source that is in conformance with the Advanced Encryption Standard for data encryption. Â© 2009 IEEE.
2,4-Dichlorobenzyl 2-methoxybenzoate
(2013) Isloor, A.M.; Garudachari, B.; Gerber, T.; Hosten, E.; Betz, R.
In the title compound, C15H12Cl2O 3, the aromatic rings make a dihedral angle of 10.78 (4)°. In the molecule, there is a short C-H?O contact. In the crystal, C-H?O contacts connect the molecules into C(7)C(8) chains along the b axis. The shortest intercentroid distance between two benzoic acid aromatic systems is 3.7416 (8) Å.