Papers by Dr Chandra C Tripathi
Advanced Science Letters, 2015
The accurate modeling of Transport characteristics is important for prediction of current–voltage... more The accurate modeling of Transport characteristics is important for prediction of current–voltage characteristics of Metal-Insulator-Metal (MIM) diode for THz energy harvesting applications. In the present paper, Nb/Nb2O5/Ta2O5/Nb, MIIM structure has been evaluated using WKB and TMM models for estimating the transport probability and current density. The total insulator thickness has been varied from 6–10 nm to evaluate the diode like behavior. Also, a review of different modeling methods used for determining the transport probability has been presented. The TMM model has been observed to result more realistic I–V characteristics, moreover the accurate modeling of MIM diodes requires an alternative model like Non-equilibrium green’s function (NEGF) approximations as it can be correlated with Metal-Insulator-Semiconductor (MIS) structure in nanoscale FET devices.
Film bulk acoustic wave resonators (FBARs) are
of great interest for wireless applications due to... more Film bulk acoustic wave resonators (FBARs) are
of great interest for wireless applications due to its
inherent advantages at microwave frequencies. However,
the presence of spurious modes near the main resonance
degrades the performance of resonators and requires
development of new methods to suppress such unwanted
modes. Different techniques are used to suppress these
spurious modes. In this paper, we present design of a new
step-like frame structure film bulk acoustic wave resonator
operating near 1.5 GHz. The simulated results are
compared with simple frame-like structure. The spurious
resonances are eliminated effectively and smooth pass
band is obtained with effective coupling coefficient of
5.68 % and quality factor of 1800. The equivalent
electrical mBVD model of the FBAR based on impedance
response is also presented. These highly smooth phase
response and passband skirt steepness resonators are most
demanding for the design of low cost, small size and high
performance filters, duplexers and oscillators for wireless
systems.
A facile sonochemical route has been proposed in which liquid phase exfoliation of graphite into ... more A facile sonochemical route has been proposed in which liquid phase exfoliation of graphite into single and multi-layer graphene
is obtained. An organic solvent ortho-dichlorobenzene (ODCB) is used for the graphene exfoliation and the effect of addition of
organic salts in ODCB solvent is investigated. The characterization of the as prepared graphene is done using SEM, TEM and
UV-Visible spectroscopy. The graphene film was prepared using vacuum filtration method and resistivity measurement was done
using Four-Probe method. The application of graphene film in making flexible paper supercapacitor is demonstrated. It is
observed that the concentration of graphene synthesized by liquid phase exfoliation method has been found to enhance
appreciably with addition of EDTA disodium salt.
he wireless power transmission (WPT) technology is an extension of wireless communication. The ph... more he wireless power transmission (WPT) technology is an extension of wireless communication. The physics of WPT and wireless communication are related, but WPT is distinct from wireless transmission for transferring information (such as radio and mobile phones etc.), where the percentage of the power that is received is only important if it becomes too low to successfully recover the signal. With WPT, the efficiency is a more critical parameter and this creates important differences in these technologies. This paper presents the wireless power transmission (WPT), from past work to most recent accomplishments including recent developments, potential approaches and factors responsible for designing most critical rectifying diodes operating at terahertz/petahertz frequencies.
Micro-electro-mechanical-systems(MEMS) switches have low resistive loss, negligible power consump... more Micro-electro-mechanical-systems(MEMS) switches have low resistive loss, negligible power consumption, good isolation and high power handling capability compared with semiconductor switches. Lifetime of capacitive shunt switches strongly depends on the actuation voltage so low voltage switches is necessary to enhance its performance as well as to broaden its application area. This paper presents the design and simulation of low voltage capacitive shunt MEMS switches together with its RF performance for high frequency applications. The low voltage switches are realized by lowering the spring constant of the beam using serpentine spring designs together with large capacitive area so as to achieve the good RF performance as well. The pull-in voltage is analyzed with commercial CAD finite element analysis software CoventorWare. The electromagnetic performance in terms of scattering parameters, insertion loss, and isolation are analyzed with software Ansoft HFSS10. The switches achieved insertion loss <0.47 dB in on state from 2 to 40 GHz; it provided better than 25 dB isolation in off state with a capacitance ratio of 94-96. The actuation voltage as low as 1.5 V with actuation area 110 × 100 µm 2 along with good RF performance is reported. The design parameter optimization including selection of appropriate number of meanders and its width found to be one of the most sensitive factors affecting the spring stiffness and actuation voltage.
Micro-electro-mechanical-systems(MEMS) switches have low resistive loss, negligible power consump... more Micro-electro-mechanical-systems(MEMS) switches have low resistive loss, negligible power consumption, good isolation and high power handling capability compared with semiconductor switches. Lifetime of capacitive shunt switches strongly depends on the actuation voltage so low voltage switches is necessary to enhance its performance as well as to broaden its application area. This paper presents the design and simulation of low voltage capacitive shunt MEMS switches together with its RF performance for high frequency applications. The low voltage switches are realized by lowering the spring constant of the beam using serpentine spring designs together with large capacitive area so as to achieve the good RF performance as well. The pull-in voltage is analyzed with commercial CAD finite element analysis software CoventorWare. The electromagnetic performance in terms of scattering parameters, insertion loss, and isolation are analyzed with software Ansoft HFSS10. The switches achieved insertion loss <0.47 dB in on state from 2 to 40 GHz; it provided better than 25 dB isolation in off state with a capacitance ratio of 94-96. The actuation voltage as low as 1.5 V with actuation area 110 × 100 µm 2 along with good RF performance is reported. The design parameter optimization including selection of appropriate number of meanders and its width found to be one of the most sensitive factors affecting the spring stiffness and actuation voltage.
The selection of a proper metal electrode, piezoelectric layer, optimization of coupling coeffici... more The selection of a proper metal electrode, piezoelectric layer, optimization of coupling coefficient and Q value of film bulk acoustic resonators (FBAR) are the key issues in the design and performance enhancement of a FBAR based bandpass filters. The optimum effective coupling coefficient is determined by studying the effect of various metal electrodes and by varying the thickness ratio of electrode and piezoelectric layer. In this paper, we present the optimum performance analysis of film bulk acoustic resonator in terms of effective coupling coefficient and spurious resonances. The optimum effective coupling coefficient of 7.1% is obtained with tungsten electrode with thickness ratio of 0.1. The spurious resonances have been minimized by different frame-like FBAR structures and simulated using COMSOL Multiphysics design tool. The boundary frame FBAR shows the best balance of performance by effectively suppressing the spurious resonances along with no reduction in effective coupling coefficient. These optimized film bulk acoustic wave resonators can be utilized for the implementation of high performance bandpass filters.
Journal of the European …, Jan 1, 2001
Thin film bulk acoustic wave (BAW) resonators and filters are appropriate for mobile communicatio... more Thin film bulk acoustic wave (BAW) resonators and filters are appropriate for mobile communication systems operating at high frequencies between 1-10 GHz. The resonance frequency is mainly determined by the thickness of the piezoelectric layer. Piezoelectric films used for this application are, therefore, several 100 nm in thickness (up to approx. 2 mm) depending on frequency. Piezoelectric thin film materials used for bulk acoustic wave devices include AlN, ZnO thin films for small bandwidth applications and also PZT films for wide bandwidth applications. Within Philips piezoelectric AlN and PbZr x Ti 1Àx O 3 (PZT) layers are investigated with respect to their potential for RF micro-electronic applications. High quality AlN films with strong c-axis orientation are achieved by optimum sputter deposition conditions and by applying suited nucleation layers. Electromechanical coupling factors k of 0.25 AE0.03, which are close to the bulk data, have been found in highly c-axis oriented AlN thin films. The relationship between sputter deposition conditions, AlN films structure on the one hand and electromechanical coupling factor k and relevant electrical parameters on the other hand will be discussed. A one-dimensional physical model is used to describe the bulk acoustic wave resonator's electrical impedance data accurately. Thin PZT films are grown via sol-gel processing. These films show high electromechanical coupling factor k of 0.3-0.6 and are therefore attractive for wide bandwidth filter applications. #
Materials chemistry and …, Jan 1, 2003
Thin film bulk acoustic wave (BAW) resonators and filters are well suited for mobile communicatio... more Thin film bulk acoustic wave (BAW) resonators and filters are well suited for mobile communication systems operating at high frequencies between 0.5 and 10GHz. Piezoelectric thin film materials investigated for BAW devices within Philips include AlN ...
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Papers by Dr Chandra C Tripathi
of great interest for wireless applications due to its
inherent advantages at microwave frequencies. However,
the presence of spurious modes near the main resonance
degrades the performance of resonators and requires
development of new methods to suppress such unwanted
modes. Different techniques are used to suppress these
spurious modes. In this paper, we present design of a new
step-like frame structure film bulk acoustic wave resonator
operating near 1.5 GHz. The simulated results are
compared with simple frame-like structure. The spurious
resonances are eliminated effectively and smooth pass
band is obtained with effective coupling coefficient of
5.68 % and quality factor of 1800. The equivalent
electrical mBVD model of the FBAR based on impedance
response is also presented. These highly smooth phase
response and passband skirt steepness resonators are most
demanding for the design of low cost, small size and high
performance filters, duplexers and oscillators for wireless
systems.
is obtained. An organic solvent ortho-dichlorobenzene (ODCB) is used for the graphene exfoliation and the effect of addition of
organic salts in ODCB solvent is investigated. The characterization of the as prepared graphene is done using SEM, TEM and
UV-Visible spectroscopy. The graphene film was prepared using vacuum filtration method and resistivity measurement was done
using Four-Probe method. The application of graphene film in making flexible paper supercapacitor is demonstrated. It is
observed that the concentration of graphene synthesized by liquid phase exfoliation method has been found to enhance
appreciably with addition of EDTA disodium salt.
of great interest for wireless applications due to its
inherent advantages at microwave frequencies. However,
the presence of spurious modes near the main resonance
degrades the performance of resonators and requires
development of new methods to suppress such unwanted
modes. Different techniques are used to suppress these
spurious modes. In this paper, we present design of a new
step-like frame structure film bulk acoustic wave resonator
operating near 1.5 GHz. The simulated results are
compared with simple frame-like structure. The spurious
resonances are eliminated effectively and smooth pass
band is obtained with effective coupling coefficient of
5.68 % and quality factor of 1800. The equivalent
electrical mBVD model of the FBAR based on impedance
response is also presented. These highly smooth phase
response and passband skirt steepness resonators are most
demanding for the design of low cost, small size and high
performance filters, duplexers and oscillators for wireless
systems.
is obtained. An organic solvent ortho-dichlorobenzene (ODCB) is used for the graphene exfoliation and the effect of addition of
organic salts in ODCB solvent is investigated. The characterization of the as prepared graphene is done using SEM, TEM and
UV-Visible spectroscopy. The graphene film was prepared using vacuum filtration method and resistivity measurement was done
using Four-Probe method. The application of graphene film in making flexible paper supercapacitor is demonstrated. It is
observed that the concentration of graphene synthesized by liquid phase exfoliation method has been found to enhance
appreciably with addition of EDTA disodium salt.