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- Antenna radiation patterns;barium compounds;coplanar waveguides;dielectric materials;dielectric thin films;ferroelectric devices;impedance matching;slot antennas;strontium compounds;varactors;Ba(1-x)SrxTiO3;CPW antenna structure;DC voltage;E-plane co-polarized patterns;H-plane co-polarized patterns;antenna miniaturization;ferroelectric BST thin film varactors;ferroelectric varactor loadings;frequency 5.3 GHz to 5.8 GHz;high dielectric constant materials;impedance matching;miniaturized antenna;reconfigurable CPW square-ring slot antenna;reconfigurable coplanar waveguide square-ring slot antenna;resonant frequency;tuning stub;Coplanar waveguides;Iron;Probes;Slot antennas;Varactors;Antenna miniaturization;coplanar waveguide (CPW) antenna;ferroelectric thin film;ferroelectric varactor;reconfigurable antenna;slot loop antenna;varactor loadings (1)
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- Barium compounds;dielectric hysteresis;electric impedance;ferroelectric capacitors;ferroelectric thin films;lead compounds;strontium compounds;thin film capacitors;varactors;(BaSr)TiO3;EMC decoupling;PZT;electromagnetic compatibility;equivalent circuit model;ferroelectric hysteresis;impedance;insertion loss;paraelectric based integrated varactors;series resistance;thin-film ferroelectric capacitors;Capacitors;Electrical resistance measurement;Electromagnetic compatibility;Electromagnetic measurements;Ferroelectric materials;Impedance measurement;Insertion loss;Loss measurement;Thin film circuits;Transistors;Algorithms;Barium Compounds;Electric Capacitance;Electrochemistry;Electromagnetic Phenomena;Ferric Compounds;Oxides;Strontium;Titanium (1)
- Capacitance;dielectric hysteresis;dielectric polarisation;ferroelectric coercive field;ferroelectric switching;ferroelectric thin films;Landau-Khalatnikov model;coercive voltage;hysteresis loop;polarization switching;thin-film ferroelectric capacitance;voltage dependence;Capacitance measurement;Capacitance-voltage characteristics;Ferroelectric materials;Hysteresis;Polarization;Transistors;Voltage (1)
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- Coplanar waveguides;current density;printed circuits;strip lines;common-mode radiated emissions;conformal mapping;coplanar stripline printed circuit boards;current density distribution;net ground plane inductance;Conductors;Current density;Current distribution;Inductance;Microstrip;Printed circuits;Stripline;Common-mode radiated emissions;conformal mapping;coplanar stripline;net ground plane inductance (1)
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- DNA-based biopolymers; dielectric properties; electrical transport in biopolymers; electric force microscopy Read More: http://www.worldscientific.com/doi/abs/10.1142/S179329200900154X (1)
- DNA;coplanar waveguide components;dielectric materials;magnesium compounds;microwave photonics;molecular electronics;polymer films;thin films;0.1 dB;0.5 dB;10 to 30 GHz;DNA based polymers;coplanar waveguide lines;dielectric constant;microwave dielectric properties;microwave frequencies;microwave photonics;polymer thin films;propagation constants;Conductors;Coplanar waveguides;DNA;Dielectrics;Microwave frequencies;Nonlinear optics;Optical films;Optical polymers;Optical waveguides;Polymer films;Coplanar waveguide (CPW) lines;dielectric deoxyribonucleic acid (DNA) based polymers;microwave characterization;microwave photonics (1)
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- Dielectric hysteresis;dielectric polarisation;ferroelectric switching;ferroelectric thin films;lead compounds;space charge;PZT thin films;Pb(ZrTi)O3;Sawyer-Tower circuit;equivalent input impedance;ferroelectric thin films;hysteresis loop;leakage resistance;linear polarization;remnant polarization;space charge effects;switching polarization;Electrical resistance measurement;Ferroelectric materials;Hysteresis;Impedance;Iron;Polarization;Shape;Space charge;Thin film circuits;Transistors (1)
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- Distributed transmission line phase shifter (1)
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- Electromagnetic bandgap (EBG); coplanar waveguide (CPW); ferroelectric varactor; tunability (1)
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Articles 1 - 30 of 34
Full-Text Articles in Engineering
Vanadium Oxide Thin-Film Variable Resistor-Based Rf Switches, Kuanchang Pan, Weisong Wang, Eunsung Shin, Kelvin Freeman, Guru Subramanyam
Vanadium Oxide Thin-Film Variable Resistor-Based Rf Switches, Kuanchang Pan, Weisong Wang, Eunsung Shin, Kelvin Freeman, Guru Subramanyam
Guru Subramanyam
Vanadium dioxide (VO2) is a unique phase change material (PCM) that possesses a metal-to-insulator transition property. Pristine VO2 has a negative temperature coefficient of resistance, and it undergoes an insulator-to-metal phase change at a transition temperature of 68°C. Such a property makes the VO2 thin-film-based variable resistor (varistor) a good candidate in reconfigurable electronics to be integrated with different RF devices such as inductors, varactors, and antennas. Series single-pole single-throw (SPST) switches with integrated VO2 thin films were designed, fabricated, and tested. The overall size of the device is 380 μm × 600 μm. The SPST switches were fabricated on …
A High Performance Ceramic-Polymer Separator For Lithium Batteries, Jitendra Kumar, Padmakar Kichambare, Amarendra K. Rai, Rabi Bhattacharya, Stanley J. Rodrigues, Guru Subramanyam
A High Performance Ceramic-Polymer Separator For Lithium Batteries, Jitendra Kumar, Padmakar Kichambare, Amarendra K. Rai, Rabi Bhattacharya, Stanley J. Rodrigues, Guru Subramanyam
Guru Subramanyam
A three-layered (ceramic-polymer-ceramic) hybrid separator was prepared by coating ceramic electrolyte [lithium aluminum germanium phosphate (LAGP)] over both sides of polyethylene (PE) polymer membrane using electron beam physical vapor deposition (EB-PVD) technique. Ionic conductivities of membranes were evaluated after soaking PE and LAGP/PE/LAGP membranes in a 1 Molar (1M) lithium hexafluroarsenate (LiAsF6) electrolyte in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in volume ratio (1:1:1). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were employed to evaluate morphology and structure of the separators before and after cycling performance tests to better understand structure-property correlation. As compared …
Industry-University Collaboration: A University Of Dayton Model, Guru Subramanyam
Industry-University Collaboration: A University Of Dayton Model, Guru Subramanyam
Guru Subramanyam
This paper introduces industry-university collaboration activities currently in place at the University of Dayton's School of Engineering. These collaborations are important to prepare industry-ready graduates who excel in technical, entrepreneurial, and leadership skills. One of the key curricular components is the industry-sponsored multidisciplinary projects. Industry involvement in advisory committee, strategic research partnerships, and other forms are discussed.
Tunable Electromagnetic Bandgap Performance Of Coplanar Waveguides Periodically Loaded By Ferroelectric Varactors, D. Kuylenstierna, Guru Subramanyam, A. Vorobiev, S. Gevorgian
Tunable Electromagnetic Bandgap Performance Of Coplanar Waveguides Periodically Loaded By Ferroelectric Varactors, D. Kuylenstierna, Guru Subramanyam, A. Vorobiev, S. Gevorgian
Guru Subramanyam
To achieve tunable electromagnetic bandgap (EBG) performance, ferroelectric varactors are considered, in LC circuits, for periodically loading coplanar waveguides (CPWs). Asymmetric or symmetric tuning of the bandgap width may be achieved by changing the capacitance of the varactors in the LC circuits. To validate this concept, tunable EBG arrays based on silicon substrate CPWs, including thin film SrTiO3 (STO) varactors, are fabricated and tested experimentally. The EBGs are designed so that the first band gap starts between 20 and 30 GHz. Up to 10% tuning is achieved, under 20-V DC applied bias, in the EBG structures.
A New Method For Electrical Characterization Of Ferroelectric Thin Films At Microwave Frequencies, Guru Subramanyam
A New Method For Electrical Characterization Of Ferroelectric Thin Films At Microwave Frequencies, Guru Subramanyam
Guru Subramanyam
Read More: http://www.worldscientific.com/doi/abs/10.1142/S179329200900154X
Capacitance Of Thin-Film Ferroelectrics Under Different Drive Signals, Huadong Li, Guru Subramanyam
Capacitance Of Thin-Film Ferroelectrics Under Different Drive Signals, Huadong Li, Guru Subramanyam
Guru Subramanyam
Thin-film ferroelectric capacitance can be obtained by 2 different methods. Capacitance obtained using the derivative of its hysteresis loop is related to large applied signals and can be called the large-signal capacitance. Capacitance measured directly with a small, applied ac signal together with a slow changing dc bias is called the small-signal capacitance. This paper investigated the voltage dependence of the large- and small-signal capacitances. Measurements show that the large-signal C-V curve of thin-film ferroelectrics has much sharper peaks and higher peak values than the small-signal C-V curve. Analyses based on the Landau-Khalatnikov model shows that practical small-signal capacitance is …
Effect Of External Electrical Stimuli On Dna-Based Biopolymers, Guru Subramanyam, Carrie Bartsch, James Grote, Rajesh Naik, Lawrence Brott, Morley Stone, Angela Campbell
Effect Of External Electrical Stimuli On Dna-Based Biopolymers, Guru Subramanyam, Carrie Bartsch, James Grote, Rajesh Naik, Lawrence Brott, Morley Stone, Angela Campbell
Guru Subramanyam
Biopolymers, such as deoxyribonucleic acid-hexadecyltrimethyl ammonium chloride (DNA-CTMA) and bovine serum albumin-polyvinyl alcohol (BSA-PVA), were studied using a novel capacitive test structure. A variety of external electrical stimuli were applied, including a low frequency alternating current signal and a rf/microwave frequency signal combined with a DC bias. The dynamic responses of the DNA-based biopolymer to the external stimuli are presented in this paper. The electrical transport measurements support the space-charge-limited conduction and the low frequency capacitance–voltage (CV) measurements showed large depletion layer capacitance at the Au–biopolymer interface, at 20 Hz, and the capacitance approaching bulk values at 1 MHz. Electric …
Thermally Controlled Vanadium Dioxide Thin Film Microwave Devices, Guru Subramanyam, E. Shin, D. Brown, H. Yue
Thermally Controlled Vanadium Dioxide Thin Film Microwave Devices, Guru Subramanyam, E. Shin, D. Brown, H. Yue
Guru Subramanyam
No abstract provided.
Design Of A Si Mmic Compatible Ferroelectric Varactor Shunt Switch For Microwave Applications, Faruque Ahamed, Guru Subramanyam
Design Of A Si Mmic Compatible Ferroelectric Varactor Shunt Switch For Microwave Applications, Faruque Ahamed, Guru Subramanyam
Guru Subramanyam
This paper describes a capacitive shunt switch, based on ferroelectric varactors as a potential replacement for RF MEMS switches for microwave applications. Our implementation is based on a coplanar waveguide (CPW) transmission line shunted by a ferroelectric varactor. The novelty in the implementation comes from the elimination of any moving parts (as in MEMS switches) for switching. The concept of switching ON and OFF is based on the dielectric tunability of the ferroelectric material of barium strontium titanium oxide (BST) thin-films. From electromagnetic simulations performed, the isolation of the switch between 20 and 40 GHz (OFF state S21) is better …
Rf Performance Evaluation Of Ferroelectric Varactor Shunt Switches, Guru Subramanyam, Faruque Ahamed, Rand Biggers, Robert Neidhard, Edward Nykiel, John Ebel, Richard Strawser, Keith Stamper, Mark Calcatera
Rf Performance Evaluation Of Ferroelectric Varactor Shunt Switches, Guru Subramanyam, Faruque Ahamed, Rand Biggers, Robert Neidhard, Edward Nykiel, John Ebel, Richard Strawser, Keith Stamper, Mark Calcatera
Guru Subramanyam
No abstract provided.
Ferroelectric Batio3/Srtio3 Multilayered Thin Films For Room-Temperature Tunable Microwave Elements, Ming Liu, Chunrui Ma, Gregory Collins, Jian Liu, Chonglin Chen, Andy D. Alemayehu, Guru Subramanyam, Ying Ding, Jianghua Chen, Chao Dai, Yuan Lin, Melanie W. Cole
Ferroelectric Batio3/Srtio3 Multilayered Thin Films For Room-Temperature Tunable Microwave Elements, Ming Liu, Chunrui Ma, Gregory Collins, Jian Liu, Chonglin Chen, Andy D. Alemayehu, Guru Subramanyam, Ying Ding, Jianghua Chen, Chao Dai, Yuan Lin, Melanie W. Cole
Guru Subramanyam
Ferroelectric BaTiO3/SrTiO3 with optimized c-axis-oriented multilayered thin films were epitaxially fabricated on (001) MgO substrates. The microstructural studies indicate that the in-plane interface relationships between the films as well as the substrate are determined to be (001)SrTiO3//(001)BaTiO3//(001)MgO and [100]SrTiO3//[100]BaTiO3//[100]MgO. The microwave (5 to 18 GHz) dielectric measurements reveal that the multilayered thin films have excellent dielectric properties with large dielectric constant, low dielectric loss, and high dielectric tunability, which suggests that the as-grown ferroelectric multilayered thin films can be developed for room-temperature tunable microwave elements and related device applications.
A Reconfigurable Cpw Bow-Tie Antenna Using An Integrated Ferroelectric Thin Film Varactor, K. C. Pan, Dustin Brown, Guru Subramanyam, R. Penno, H. Jiang, C. H. Zhang, M. Patterson, David Kuhl, Kevin Leedy, Charles Cerny
A Reconfigurable Cpw Bow-Tie Antenna Using An Integrated Ferroelectric Thin Film Varactor, K. C. Pan, Dustin Brown, Guru Subramanyam, R. Penno, H. Jiang, C. H. Zhang, M. Patterson, David Kuhl, Kevin Leedy, Charles Cerny
Guru Subramanyam
A novel printed antenna with a frequency reconfigurable feed network is presented. The antenna consists of a bowtie structure patch radiating element in the inner space of an annulus that is on a nongrounded substrate with a ferroelectric (FE) Barium Strontium Titanate (BST) thin film. The bowtie patch is fed by a coplanar waveguide (CPW) transmission line that also includes a CPW-based BST shunt varactor. Reconfiguration of the compact 8 mm × 8 mm system has been demonstrated by shifting the antenna system’s operating frequency 500 MHz in the 7–9 GHz band by applying a DC voltage bias.
Large Area Bst Thin Films For Microwave Applications Deposited By Pulsed Laser Ablation, C. Varanasi, K. Leedy, D. Tomich, Guru Subramanyam
Large Area Bst Thin Films For Microwave Applications Deposited By Pulsed Laser Ablation, C. Varanasi, K. Leedy, D. Tomich, Guru Subramanyam
Guru Subramanyam
Large area Ba1 − xSrxTiO3 (BST) thin films with x = 0.4 or x = 0.5 were deposited on 75 mm diameter Si wafers in a pulsed laser deposition (PLD) chamber enabling full-wafer device fabrication using standard lithography. The deposition conditions were re-optimized for large PLD chambers to obtain uniform film thickness, grain size, crystal structure, orientation, and dielectric properties of BST films. X-ray diffraction and microstructural analyses on the BST films grown on Pt/Au/Ti electrodes deposited on SiO2/Si wafers revealed films with (110) preferred orientation with a grain size < 100 nm. An area map of the thickness and crystal …
Highly Efficient Quantum-Dot Light Emitting Diodes With Dna-Ctma As Combined Hole Transporting And Electron-Blocking Layer, Q. Sun, Guru Subramanyam, Liming Dai, M. Check, A. Campbell, Rajesh Naik, James Grote, Yongqiang Wang
Highly Efficient Quantum-Dot Light Emitting Diodes With Dna-Ctma As Combined Hole Transporting And Electron-Blocking Layer, Q. Sun, Guru Subramanyam, Liming Dai, M. Check, A. Campbell, Rajesh Naik, James Grote, Yongqiang Wang
Guru Subramanyam
Owing to their narrow bright emission band, broad size-tunable emission wavelength, superior photostability, and excellent flexible-substrate compatibility, light-emitting diodes based on quantum dots (QD-LEDs) are currently under intensive research and development for multiple consumer applications including flat-panel displays and flat lighting. However, their commercialization is still precluded by the slow development to date of efficient QD-LEDs as even the highest reported efficiency of 2.0% cannot favorably compete with their organic counterparts. Here, we report QD-LEDs with a record high efficiency (∼4%), high brightness (∼6580 cd/m2), low turn-on voltage (∼2.6 V), and significantly improved color purity by simply using deoxyribonucleic acid …
Enhanced Dielectric Properties Of (Ba,Sr)Tio3//Ba(Zr,Ti)O-3 Heterostructures With Optimized Structure Design, Ming Liu, Jian Liu, Chunrui Ma, Gregory Collins, Chonglin Chen, Andy Alemayehu, Guru Subramanyam, Jie He, Jiechao Jiang, Efstathios Meletis, Amar Bhalla
Enhanced Dielectric Properties Of (Ba,Sr)Tio3//Ba(Zr,Ti)O-3 Heterostructures With Optimized Structure Design, Ming Liu, Jian Liu, Chunrui Ma, Gregory Collins, Chonglin Chen, Andy Alemayehu, Guru Subramanyam, Jie He, Jiechao Jiang, Efstathios Meletis, Amar Bhalla
Guru Subramanyam
Environment-friendly ferroelectric Mn:BST//Mn:BZT heterostructures were epitaxially deposited on (001) MgO substrates by pulsed laser deposition with different combination ratios of Mn:BST over Mn:BZT, 2.5:7.5; 1:1; and 7.5:2.5. The microstructural studies indicate that the in-plane interface relationships between the heterostructures and the substrate are determined to be (001)Mn:BST//(001)Mn:BZT//(001)MgO and [100]Mn:BST//[100]Mn:BZT//[100]MgO. The Ku band microwave (15.5–18 GHz) dielectric property characterizations show that the dielectric constant, dielectric loss, and tunabilities of the heterostructures are highly dependent upon the sequences of Mn:BST to Mn:BZT. The optimized dielectric tunability with a low loss tangent was found to be 58.1%–74.4% under the combination ratio of 1:1 …
A New Ferroelectric Varactor Shunt Switch For Microwave And Millimeterwave Reconfigurable Circuits, Guru Subramanyam, Faruque Ahamed, Rand Biggers, Angela Campbell, Robert Neidhard, Edward Nykiel, Rebecca Cortez, Keith Stamper, Mark Calcatera
A New Ferroelectric Varactor Shunt Switch For Microwave And Millimeterwave Reconfigurable Circuits, Guru Subramanyam, Faruque Ahamed, Rand Biggers, Angela Campbell, Robert Neidhard, Edward Nykiel, Rebecca Cortez, Keith Stamper, Mark Calcatera
Guru Subramanyam
This paper presents a ferroelectric varactor shunt switch which can be useful for microwave/millimeterwave switching as well as for the design of reconfigurable circuits. The device operation is based on nonlinear dielectric tunability of a ferroelectric thin-film sandwiched between two metal layers in the parallel plate configuration. A CPW based design allows for MMIC compatible shunt switches with low insertion loss and high isolation. Experimental performance of the varactor shunt switch indicates good switching performance with ~24 dB isolation @41 GHz, and insertion loss below 7 dB up to 45 GHz.
Ferroelectric Thin-Film Based Two-Dimensional Electromagnetic Structures, U. Khan, Guru Subramanyam, S. Gevorgian, A. Vorobiev
Ferroelectric Thin-Film Based Two-Dimensional Electromagnetic Structures, U. Khan, Guru Subramanyam, S. Gevorgian, A. Vorobiev
Guru Subramanyam
A two-dimensional electromagnetic bandgap structure has been developed using ferroelectric thin-films. Using lumped inductors and parallel plate capacitors a planar structure is developed which creates a bandgap in the 20–40 GHz range, as demonstrated by experimental results. The ferroelectric material Ba0.6Sr0.4TiO3 (BST) is used in the form of a thin-film between patterned layers of gold to form capacitors on a 500 μm thick high-resistivity Si substrate. A meander line based design is used to form the two-dimensional surface which provides biasing pathways to the varactors. The concept is simulated and experimentally verified using a coplanar waveguide based device in which …
Performance Of Thin-Film Ferroelectric Capacitors For Emc Decoupling, Huadong Li, Guru Subramanyam
Performance Of Thin-Film Ferroelectric Capacitors For Emc Decoupling, Huadong Li, Guru Subramanyam
Guru Subramanyam
This paper studied the effects of thin-film ferroelectrics as decoupling capacitors for electromagnetic compatibility applications. The impedance and insertion loss of PZT capacitors were measured and compared with the results from commercial off-the-shelf capacitors. An equivalent circuit model was extracted from the experimental results, and a considerable series resistance was found to exist in ferroelectric capacitors. This resistance gives rise to the observed performance difference around series resonance between ferroelectric PZT capacitors and normal capacitors. Measurements on paraelectric (Ba,Sr)TiO3-based integrated varactors do not show this significant resistance. Some analyses were made to investigate the mechanisms, and it was …
A New Capacitive Test Structure For Microwave Characterization Of Biopolymers, Carrie M. Bartsch, Guru Subramanyam, James Grote, Frank K. Hopkins, Lawrence L. Brott, Rajesh R. Naik
A New Capacitive Test Structure For Microwave Characterization Of Biopolymers, Carrie M. Bartsch, Guru Subramanyam, James Grote, Frank K. Hopkins, Lawrence L. Brott, Rajesh R. Naik
Guru Subramanyam
A new capacitive test structure, containing a parallel plate capacitor with coplanar waveguide feed lines, was used for microwave characterization of biopolymers for the first time. Microwave dielectric properties were obtained for the biopolymers as a function of dc bias and temperature by performing on-wafer microwave measurements. Dielectric tunability was observed with applied dc bias in the biopolymers tested.
A Memristor Device Model, Chris Yakopcic, Tarek Taha, Guru Subramanyam
A Memristor Device Model, Chris Yakopcic, Tarek Taha, Guru Subramanyam
Guru Subramanyam
This letter proposes a new mathematical model for memristor devices. It builds on existing models and is correlated against several published device characterizations. This letter identifies significant discrepancies between the existing models and published device characterization data. The proposed model addresses these discrepancies. In particular, it allows modeling of memristor-based neuromorphic systems.
Microwave Characterization Of Nanostructured Ferroelectric Ba0.6sr0.4tio3 Thin Films Fabricated By Pulsed Laser Deposition, Angela Campbell, Rand Biggers, Guru Subramanyam, Gregory Kozlowski, Richard Kleismit, Hollie Zate, Simon Hopkins, Bartek Glowacki, Bonnie Riehl, Timothy Peterson
Microwave Characterization Of Nanostructured Ferroelectric Ba0.6sr0.4tio3 Thin Films Fabricated By Pulsed Laser Deposition, Angela Campbell, Rand Biggers, Guru Subramanyam, Gregory Kozlowski, Richard Kleismit, Hollie Zate, Simon Hopkins, Bartek Glowacki, Bonnie Riehl, Timothy Peterson
Guru Subramanyam
A series of nanostructured ferroelectric thin films of barium strontium titanate were fabricated using a pulsed laser deposition system with real-time in situ process control. Pulsed laser deposition parameters were controlled during the growth of nanostructured thin films for use in the development of high frequency tunable microwave devices. The thin films were all grown at the same substrate temperature and laser beam energy density, but the chamber oxygen partial pressure (COPP) was varied systematically from 19 mTorr through 1000 Torr. Structural and electromagnetic characterization was performed using atomic force microscopy and evanescent microwave microscopy, respectively. Atomic force microscopy showed …
Microwave Dielectric Properties Of Dna Based Polymers Between 10 And 30 Ghz, Guru Subramanyam, E. Heckman, James Grote, K. Hopkins
Microwave Dielectric Properties Of Dna Based Polymers Between 10 And 30 Ghz, Guru Subramanyam, E. Heckman, James Grote, K. Hopkins
Guru Subramanyam
Deoxyribonucleic acid (DNA) based polymer thin-films were characterized at microwave frequencies for the first time. The dielectric properties of the film were extracted from comparison of the propagation constants of the co-planar waveguide (CPW) lines on bare MgO substrates and the DNA based films on MgO substrates. The insertion loss introduced by the DNA film is only 0.1 dB at 10 GHz and 0.5 dB at 30 GHz. The relative dielectric constant of the DNA based film averages to four at microwave frequencies, and the loss-tangent was below 0.1 up to 30 GHz.
Closed-Form Expression For The Net Ground Plane Inductance Of Coplanar Stripline Pcbs, Li Huadong, Guru Subramanyam
Closed-Form Expression For The Net Ground Plane Inductance Of Coplanar Stripline Pcbs, Li Huadong, Guru Subramanyam
Guru Subramanyam
The net ground plane inductance of printed circuit boards is the source of common-mode radiated emissions. Correct determination of the net ground plane inductance provides a quick estimation of the radiated emissions from printed circuit boards. Employing conformal mapping technique, this paper gives a closed-form expression for the per unit length net ground plane inductance of coplanar stripline printed circuit boards with finite ground plane width. Current density distribution on the ground plane is also obtained.
A Low Voltage Tunable Analog Phase Shifter Utilizing Ferroelectric Varactors, Guru Subramanyam, Kevin Leedy, Chakrapani Varanasi, Robert Neidhard, Keith Stamper, Mark Calcatera
A Low Voltage Tunable Analog Phase Shifter Utilizing Ferroelectric Varactors, Guru Subramanyam, Kevin Leedy, Chakrapani Varanasi, Robert Neidhard, Keith Stamper, Mark Calcatera
Guru Subramanyam
A distributed transmission line phase shifter was implemented by periodically loading a coplanar transmission line using ferroelectric varactors in a shunt configuration. A single dc bias applied to the phase shifter circuit provides a large relative phase shift. A relative phase shift of ∼ 305 degrees was obtained at 20 GHz for a dc bias of only 5 V.
Generalized Memristive Device Spice Model And Its Application In Circuit Design, Chris Yakopcic, Tarek Taha, Guru Subramanyam, R. Pino
Generalized Memristive Device Spice Model And Its Application In Circuit Design, Chris Yakopcic, Tarek Taha, Guru Subramanyam, R. Pino
Guru Subramanyam
This paper presents a SPICE model for memristive devices. It builds on existing models and is correlated against several published device characterization data with an average error of 6.04%. When compared to existing alternatives, the proposed model can more accurately simulate a wide range of published memristors. The model is also tested in large circuits with up to 256 memristors, and was less likely to cause convergence errors when compared to other models. We show that the model can be used to study the impact of memristive device variation within a circuit. We examine the impact of nonuniformity in device …
Microwave Dielectric Properties Of Epitaxial Mn-Doped Ba(Zr,Ti)O-3 Thin Films On Laalo3 Substrates, Ming Liu, Chunrui Ma, Jian Liu, Gregory Collins, Chonglin Chen, Andy Alemayehu, Guru Subramanyam, Chao Dai, Yuan Lin, Amar Bhalla
Microwave Dielectric Properties Of Epitaxial Mn-Doped Ba(Zr,Ti)O-3 Thin Films On Laalo3 Substrates, Ming Liu, Chunrui Ma, Jian Liu, Gregory Collins, Chonglin Chen, Andy Alemayehu, Guru Subramanyam, Chao Dai, Yuan Lin, Amar Bhalla
Guru Subramanyam
Environmental friendly ferroelectric relaxor Ba(Zr0.2Ti0.8)O3 thin films with an additional 2% Mn dopant were epitaxially fabricated on the (001) LaAlO3 single crystal substrates by pulsed laser deposition. Microstructure characterizations from x-ray diffraction suggest that the films are c-axis oriented with the interface relationship of [101]Mn:BZT//[100]LAO and (001)Mn:BZT //(001)LAO. The microwave dielectric property measurements (13–17.5 GHz) reveal that the films have excellent dielectric properties with large tunability, high dielectric constant, and low dielectric loss, which the average value is 25.9%, 169 and 0.054, respectively. It is indicated that the additional 2% Mn doped Ba(Zr0.2Ti0.8)O3 thin films can be used for the …
Influence Of Space-Charge On Hysteresis Loop Characteristics Of Ferroelectric Thin Films, Huadong Li, Guru Subramanyam, S. Dey
Influence Of Space-Charge On Hysteresis Loop Characteristics Of Ferroelectric Thin Films, Huadong Li, Guru Subramanyam, S. Dey
Guru Subramanyam
Hysteresis loops of Pb(Zr, Ti)O3 (PZT) thin films obtained by using a Sawyer-Tower (ST) circuit are affected by many factors. This paper investigated the influence of space charge on the hysteresis loop of thin-film ferroelectrics, based on the model that polarization consists of two parts: linear and switching polarization. It is found that the space charge affects both the shape and offset of the ideal hysteresis loop. Further investigation shows that the practical hysteresis loop has a close relationship with the equivalent ST circuit parameters: the leakage resistance of the FE film, the equivalent input impedance of the measurement equipment, …
Miniaturized And Reconfigurable Cpw Square Ring Slot Antenna Loaded With Bst Thin Film Varactors, Hai Jiang, Mark Patterson, Dustin Brown, Chenhao Zhang, Kuanchang Pan, Guru Subramanyam, David Kuhl, Kevin Leedy, Charles Cerny
Miniaturized And Reconfigurable Cpw Square Ring Slot Antenna Loaded With Bst Thin Film Varactors, Hai Jiang, Mark Patterson, Dustin Brown, Chenhao Zhang, Kuanchang Pan, Guru Subramanyam, David Kuhl, Kevin Leedy, Charles Cerny
Guru Subramanyam
A novel miniaturized and reconfigurable coplanar waveguide (CPW) square-ring slot antenna is presented in this paper. The miniaturization is achieved via a hybrid approach including ferroelectric varactor loadings, high dielectric constant materials, and tuning stub for impedance matching. For the first time, nine shunt ferroelectric (FE) BST (Ba(1-x)SrxTiO3) thin film varactors are integrated with the CPW antenna structure achieving both antenna miniaturization and reconfiguration at the same time. The size of the miniaturized antenna is reduced to 0.067λ0 0.067λ0 without ground, and 0.1λ0 0.1λ0 with ground. The resonant frequency of the miniaturized antenna can be reconfigured from 5.3 GHz to …
Novel Multi-Capacitor Architecture For Bst Thin Film Varactors, Guru Subramanyam, M. Patterson, K. Leedy, R. Neidhard, C. Varanasi, G. Steinhauer
Novel Multi-Capacitor Architecture For Bst Thin Film Varactors, Guru Subramanyam, M. Patterson, K. Leedy, R. Neidhard, C. Varanasi, G. Steinhauer
Guru Subramanyam
Novel Barium Strontium Titanate (BST) thin film varactors with parallel capacitor architecture were designed fabricated and tested. Varactors with 2–6 parallel capacitors were experimentally verified using large area processed bst thin films. The multicapacitor varactor shunt switches provided improved isolation at the expense of higher insertion loss. The multicapacitor varactors yielded reduced overall parasitic series inductance and resistances, resulting in higher quality factor Q. This is the first time such a device is reported.
Challenges And Opportunities For Multi-Functional Oxide Thin Films For Voltage Tunable Radio Frequency/Microwave Components, Guru Subramanyam, M. W. Cole, Nian X. Sung, Thottam S. Kalkur, Nick M. Sbrockey, Gary S. Tompa, Xiaomei Guo, Chonglin Chen, S. P. Alpay, G. A. Rosetti Jr., Kaushik Dayal, Long-Qing Chen, Darrell G. Schlom
Challenges And Opportunities For Multi-Functional Oxide Thin Films For Voltage Tunable Radio Frequency/Microwave Components, Guru Subramanyam, M. W. Cole, Nian X. Sung, Thottam S. Kalkur, Nick M. Sbrockey, Gary S. Tompa, Xiaomei Guo, Chonglin Chen, S. P. Alpay, G. A. Rosetti Jr., Kaushik Dayal, Long-Qing Chen, Darrell G. Schlom
Guru Subramanyam
There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BSTthin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in …