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Electrical and Computer Engineering, 2008. ICECE 2008. International Conference on

Date 20-22 Dec. 2008

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Displaying Results 1 - 25 of 200
  • Improvement of load frequency control with fuzzy gain scheduled SMES unit considering governor dead-band and GRC

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (194 KB) |  | HTML iconHTML  

    Since a superconducting magnetic energy storage (SMES) unit with a self-commutated converter is capable of controlling both the active and reactive power simultaneously and quickly, increasing attention has been focused recently on power system stabilization by SMES control. In this study, a fuzzy gain scheduled supplementary control scheme with SMES unit is proposed and applied to automatic generation control (AGC) in power system for the improvement of load frequency control (LFC). The performances of the system for load changes in the areas in the interconnected power system are studied. The computer simulation of the interconnected power system shows that SMES unit with the proposed gain scheduled supplementary controller can perform a more effective primary frequency control for multi area power system. View full abstract»

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  • Computerized modelling of hybrid energy system— Part I: Problem formulation and model development

    Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1090 KB) |  | HTML iconHTML  

    A well designed hybrid energy system can be cost effective, has a high reliability and can improve the quality of life in remote rural areas. The economic constraints can be met, if these systems are fundamentally well designed, use appropriate technology and make use effective dispatch control techniques. The first part of this tri-series paper, presents the analysis and design of a mixed integer linear mathematical programming model (time series) to determine the optimal operation and cost optimization for a hybrid energy generation system consisting of a photovoltaic array, biomass, biogas, small/micro hydro, a battery bank and a fossil fuel generator. The optimization is aimed at minimizing the cost function based on demand and potential constraints. Further, mathematical models of all other components of hybrid energy system are also developed. This is the generation mix of the remote rural area of India; it may be applied to other rural areas also. View full abstract»

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  • Computerized modelling of hybrid energy system— Part II: Combined dispatch strategies and solution algorithm

    Page(s): 13 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1080 KB) |  | HTML iconHTML  

    Computer simulation is an increasingly popular tool for determining the most suitable hybrid energy system type, design and control for an isolated community or a cluster of villages. This paper presents the development of the optimum control algorithm based on combined dispatch strategies, to achieve the optimal cost of battery incorporated hybrid energy system for electricity generation, during a period of time by solving the mathematical model, which was developed in Part I. The main purpose of the control system proposed here is to reduce, as much as possible, the participation of the diesel generator in the electricity generation process, taking the maximum advantage of the renewable sources available. The overall load dispatch scenario is controlled by the availability of renewable power, total system load demand, diesel generator operational constraints and the proper management of the battery bank. The incorporation of a battery bank makes the control operation more practical and relatively easier. View full abstract»

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  • Computerized modelling of hybrid energy system— Part III: Case study with simulation results

    Page(s): 19 - 24
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1084 KB) |  | HTML iconHTML  

    This paper presents the results of the application of model (developed in Part-I) and simulation algorithm (developed in Part-II) for determining the techno-economics of battery storage type hybrid energy system intended to supply the load demand of a rural remote area having a cluster of nine villages (grid isolated). The hour-by-hour simulation model is intended to simulate a typical one month period of system operation. For simulation purpose, hourly solar insolation data and load demand data have been generated and used as an input data. The economic analysis has resulted in the calculation of optimized hourly, daily, and monthly system unit cost of proposed hybrid energy system. The obtained results represent also a helpful reference for energy planners in Uttarakhand state and justify the consideration of hybrid energy systems more seriously. View full abstract»

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  • Control and instrumentation for small wind turbines

    Page(s): 25 - 31
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (481 KB) |  | HTML iconHTML  

    Details of control and instrumentation for on-grid and off-grid operation of a small induction generator based wind turbine are presented in this paper. A micro-controller based system controller is used to connect/disconnect the wind power generator to the grid, and also to maintain the grid connection. Several real time situations are considered during the operation of the wind power generation system to test the designed control and instrumentation. The energy generated during the operation in the off-grid mode can be used for space heating or for consumer load which needs stable voltage in spite of the wind or the load variations. To achieve this, a phase control relay based electronic PI controller is designed which maintain the more or less constant voltage at the load terminal. In this research, a dump load is used and its terminal voltage is regulated by controlling the phase control relay. System instrumentation and test results are presented in this paper. View full abstract»

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  • Characteristics of the induced currents in horizontal conductors due to a nearby lightning strike

    Page(s): 32 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1059 KB) |  | HTML iconHTML  

    A nearby lightning strike can induce significant currents in long horizontal and tall down conductors. Although the magnitude of the current in this case is much smaller than that encountered during a direct strike, the probability of occurrence and the frequency content is higher. In view of this, appropriate knowledge of the characteristics of such induced currents is relevant for the interpretation of recorded currents. Considering these, the present paper discusses a modeling procedure that permits simulation of lightning-induced voltages or currents on overhead lines due to a nearby lightning strikes. The hypothesis of perfect conducting ground, generally adopted in studies on the subject, is discussed in order to better assess the validity of the simulation results. In this paper, homogeneous non-perfect ground is also investigated for the influence of lightning-induced voltage. The procedure for analyses of the voltages induced on an overhead line by a nearby lightning return stroke with a striking point in an unequal distance from the line terminations. The analysis shows that lightning induced voltages depend on the soil conductivity. View full abstract»

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  • Self-excited single-phase and three-phase induction generators in remote areas

    Page(s): 38 - 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1445 KB) |  | HTML iconHTML  

    Self-excited induction generators are increasingly being used in remote areas to generate electrical power from both conventional and nonconventional energy sources. This paper describes a method of evaluating the steady state characteristics of a single-phase as well as a three-phase induction generator for stand-alone operation. The steady state problem is formulated in a very general way so that the same solution technique can be applied to both single-phase and three-phase generators. A numerical based routine is then used to solve the formulated problem and that eliminates the additional algebraic calculations needed to explicitly express the equations in terms of actual unknowns. The proposed method is then applied to evaluate the steady state characteristics of a number of single-phase and three-phase induction generators. The simulation results obtained by the proposed method are also compared with the corresponding experimental values and are found to be in very good agreement. View full abstract»

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  • Effect of lightning return stroke current parameter’s on the components of lightning generated vertical electric field over finitely conducting earth

    Page(s): 43 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1108 KB) |  | HTML iconHTML  

    The scope of this paper is to investigate the effects of lightning induced return stroke current parameters such as peak value, velocity of propagation and cloud height, and the distance of observation point from lightning strike point on the electrostatic, induction and radiation components of lightning generated vertical electric field in time domain. Modified dipole technique has been used in this paper to perform these investigations on and above the finitely conducting earthpsilas surface. The use of modified dipole technique has overcome the limitations of conventionally used Sommerfeld integral and wave-tilt function methods for lightning induced field analyses. It has been observed that all the components of vertical electric field are highly affected by the peak value of lightning induced return stroke current and the distance of observation point from lightning strike point. The effects of velocity of propagation of lightning current on the electrostatic and radiation components are greater than that of induction component. The radiation component is not affected by the cloud height. View full abstract»

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  • Fuzzy based micro calcification segmentation

    Page(s): 49 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    Breast cancer is one of the leading causes of women death in the world. Since the causes are unknown, breast cancer cannot be prevented. Micro calcifications are the earliest signs of breast cancer and their detection is one of the most important research areas now. A novel approach for image segmentation of denser mammography images is introduced, for more accurate detection of microcalcifications clusters. In original mammographic images obtained by X-ray radiography, most of the information is hidden to the human observer. The fundamental idea of the proposed approach is to fuzzify the original image of a mammogram in order to make the difference between the backgrounds and object more. Then we enhance the region of interest and simultaneously suppress the tissues along with background thereby we do segmentation. The advantage of the proposed method is its ability to detect micro calcifications in very dense breast mammograms and also not to loose any vital data .Lot of clinical mammograms was used to test the fidelity of this algorithm. The experiments suggest that the micro calcifications are not only accurately detected but also enhance the visibility of micro calcifications. View full abstract»

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  • Compression of ECG signal based on its deviation from a reference signal using discrete cosine transform

    Page(s): 53 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1491 KB) |  | HTML iconHTML  

    In this paper a discrete cosine transform (DCT) based ECG signal compression method is proposed. DCT is applied on the residual beats of ECG signal obtained after subtracting the period normalized and dc removed beats from a reference beat. The quantization and the threshold vectors are optimized to minimize the entropy of the quantized coefficients for a target distortion. The quantized coefficients are lossless encoded for further compression. Simulation result shows that the proposed method ensures higher compression ratio than the conventional methods published in the literature. View full abstract»

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  • Effects of white matter on EEG of multi-layered spherical head models

    Page(s): 59 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1341 KB) |  | HTML iconHTML  

    Biological tissues are multi-compartmental inhomogeneous media composed of different cellular and subcellular domains. Human head, a multi-compartmental inhomogeneous medium, is composed of scalp, skull, cerebrospinal fluid (CSF), gray matter (GM), white matter (WM), and other subcellular domains. Among these domains, skull and WM show the complicated anisotropy tissue property because of their physiological structure. However, many researchers model human head excluding WM. This research investigates the necessity of WM using four- and five- layered spherical head models. Fourlayered head model excludes WM while five-layered model includes it. The piecewise homogeneous forward model using finite element method is implemented to measure electroencephalogram (EEG) on head surface for both head models. Analyzing these EEGs, this research finds the necessity of using WM to make an accurate human head model. View full abstract»

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  • Acquisition and analysis of electrogastrogram for digestive system disorders using a novel approach

    Page(s): 65 - 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB) |  | HTML iconHTML  

    The digestive system is the one of the important system in the human body, which plays major role directly or indirectly for the function of human body. Most of the people around the world have the digestive system disorders due to improper digestion of food due to inefficient performance of stomach activity. The main objective of this paper is to propose a novel method of finding the digestive system disorders using electrogastrogram [EGG], which is a non-invasive, cheap and painless method by detecting the electrical signal from the stomach cutaneously and also it act as a preliminary investigation without a need for endoscopy which is painful investigation. The recording setup explained in this proposed system includes LabVIEW software and hardware which is used to record the EGG for more than hundred patients, nearly 75% of the patients suffered from results in digestive system disorders such as Dyspepsia, Stomach ulcer, nausea, cyclic vomiting syndrome, etc. For the above said digestive system disorders dissimilarity is found in its frequency and amplitude compared with its normal individual parameter (3 cpm) at a fair amount of accuracy. View full abstract»

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  • Bioinformatics web data and service integration - An experiemnt with Gene Regulatory Networks

    Page(s): 70 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1057 KB) |  | HTML iconHTML  

    Web data integration has been an active research topic for the last few years. Bioinformatics is a huge domain wealth of data. By reverse engineering web data, in this paper we report a Java based implementation of biologically relevant application of web data integration consisting of few sites such as Flybase, YMF and STAMP. We have developed a tool that can automate the finding of transcription factor binding sites for arbitrary gene regulatory networks. We employed vertical (i.e link) and horizontal (i.e combine) integration for the whole process. As a running example and proof of concept of our approach, we report here a real example motivated by the biological domain of Drosophila Melanogaster model organism database. For a given set of genes, we could find a set of sequences (800~1500 bp) from Flybase site, then we feed those into YMF site to get a motif of 6{~}8 bp. The result motifs were fed into STAMP site and by combining result from Fly curated by Bergman and by TRANSFAC, we were able to get a sample correct result for a Bicoid gene, namely bin. The lesson learned from the exercise can be applied in generic dynamic web form based data integration application like e-commerce, comparison shopping etc. View full abstract»

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  • A new digital signal processor for Doppler radar cardiopulmonary monitoring system

    Page(s): 76 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1078 KB) |  | HTML iconHTML  

    Remote sensing and monitoring of cardiopulmonary activities based on direct conversion Doppler radar shows promise in medical and security applications. For accurate sensing, demodulation of the quadrature outputs of a direct-conversion Doppler radar is a great challenge. A digital signal processor based on Kalman filtering and principal component combining of quadrature channels is suggested. Rate detection ability and success ratio is evaluated and compared with other techniques. This radar sensor system achieves good detection accuracy in increased noise power level. View full abstract»

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  • Design of a cost-effective EMG driven bionic leg

    Page(s): 80 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1313 KB) |  | HTML iconHTML  

    Conventional low cost leg prosthesis, available in Third World countries, is essentially a fixed passive structure which makes walking possible with some difficulty, and climbing stairs with such is extremely difficult. The present work was taken to design prosthesis for above-knee amputees. The low cost bionic leg prosthesis, which has an active (battery powered) limited rotational movement of the knee joint, is controlled by voluntary EMG (electromyogram) signals from two opposing muscles from the thigh; one to rotate the leg backward (flexion) and the other forward (extension). The design involved developing the necessary EMG and processing circuitry, interfacing the output to the microcontroller, developing the driving circuitry for bidirectional rotation of the motor, and programming the microcontroller. During the course of the present work it was possible to control the rotation of a motor using a simulated EMG signal. The completed designed prosthesis will allow a user not only to walk with a better gait, but also to climb stairs with ease. View full abstract»

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  • EM radiation from Wi-LAN base station and its’ effects in human body

    Page(s): 86 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1428 KB) |  | HTML iconHTML  

    EM Fields have adverse effects on Human health. Tissue damage could occur due to the body inability to cope with the excessive heat that could be generated during the exposure to Radio Frequency. The parameters of concern with respect to human health are the rate at which a person absorbs electromagnetic energy, called the specific absorption rate (SAR). Electric field intensities from wireless LAN were measured at IIUM Campus. Using a developed flat phantom model, electric field and SAR variations for human organs are simulated and presented in this paper. The peak SAR values are compared with recommended values. View full abstract»

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  • Maximization of system lifetime in body sensor networks

    Page(s): 92 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    In this paper, the target is to reduce the energy consumption in the body sensor network as well as maximize the system lifetime of sensor nodes when they will make communication among body sensors and personal communication unit. The best compression technique like LPC is selected for energy saving based on some calculations. Formulation of a linear programming problem where is to maximize the system lifetime which is equivalent to the time until the first node runs out of battery. Maximum system lifetimes are calculated by MATLAB optimization technique using and without using efficient compression algorithm like LPC in various environments. The results show that maximum system lifetimes calculated in different scenarios using efficient compression technique like LPC is better than without using compression technique. View full abstract»

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  • Power spectral analysis for identifying the onset and termination of obstructive sleep apnoea events in ECG recordings

    Page(s): 96 - 100
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (102 KB) |  | HTML iconHTML  

    The high prevalence of obstructive sleep apnoea (OSA) requires a simplified, unattended screening device that would be useful for diagnosis at the early stage. This study presents a method for screening individual OSA event based on sleep ECG signal. The overnight ECG recordings were divided into 5-second epochs containing normal (N) breathing and onset (O), maximum (M) & termination (T) of OSA events. Power spectral analysis of ECG epochs was employed to extract features. The area under receiver operating characteristics curve was estimated to determine the discrimination capability of each feature (or power in each frequency bin). The maximum ROC areas for N/O, N/M and N/T were found to be 0.78, 0.81,0.71 in the ranges of powers of 57-65 Hz, 52-72 Hz, 52-66 Hz bands respectively. An heuristic rule was applied to recognize the individual OSA events from spectral features of N,O,M,T epochs. Results show good agreement with the original annotations in an overnight sleep study. These results, therefore, could have considerable potential in ECG based screening and can aid sleep specialist in the assessment of patients with suspected sleep apnoea syndrome. View full abstract»

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  • Performance evaluation of a high-birefringence linearly chirped grating for PMD compensation in WDM/ IM-DD transmission system

    Page(s): 101 - 106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1221 KB) |  | HTML iconHTML  

    We analytically evaluated the performance of an adjustable polarization mode dispersion compensator based on a 2-cm long high-birefringence linearly chirped fiber Bragg grating and simulated a 4-channel WDM/IMDD system using this compensator. The device can adjust differential group delay in a linearly continuous way without affecting wavelength outside the bandwidth. The various properties of the device such as relative group delay, reflectivity, differential group delay etc. are investigated in terms of wavelength and stretching ratio. Results show that under stretched condition; the device generates a time-delay between fast and slow polarization axes that is adjustable from 0 ps to 55 ps and is tunable within 2.4 nm wavelength range. Through simulation, it is also found that the power penalty is reduced from 7.10 db to 4.5 dB at a mean DGD 40 ps for a 4-channel 10 Gb/s WDM system when no stretched is applied on the grating. View full abstract»

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  • Synthesis of CMOS OTA based communication circuit

    Page(s): 107 - 112
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (995 KB) |  | HTML iconHTML  

    In this paper, a generalized design methodology for operational transconductance amplifier (OTA) based current mode radio frequency (RF) communication circuit is proposed. Three novel communication circuits, phase lock loop (PLL), adaptive delta modulator (ADM) and data compressor have been simulated. In the first implementation, direct frequency modulation is used to realize PLL, while the second gives coded pulse modulation system, which employs sampling, quantizing and coding to convert analog waveforms into digital signals. Finally, the third circuit implements data compression in digital communication system. Performance of the circuits realized with OTAs has been demonstrated through SPICE simulation. View full abstract»

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  • Optical directional coupler switch using domain inversion technology

    Page(s): 113 - 116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (206 KB) |  | HTML iconHTML  

    The switching voltage reduction in optical directional coupler switch utilizing alternating Deltabeta is fully analyzed. It is shown that increasing the number of sections in electrode can reduce the switching voltage significantly. But high-speed operation of the switch is limited as the number of electrode-section increases. In this paper, the improvements of above problems are discussed. By the introduction of domain inversion technology in lithium niobate (LiNbO3), lower switching voltage and high-speed operation of the optical directional coupler switch can be achieved. View full abstract»

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  • A new switching algorithm for TSISS network

    Page(s): 117 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1216 KB) |  | HTML iconHTML  

    Time slot interchange and signal separator (TSISS) network was introduced to reduce the time slot requirement of TST architecture. In the switching algorithm of the TSISS network, an adjacency matrix was formed and breath-first search (BFS) or depth-first search (DFS) algorithms was applied on the matrix to find optimal input and output time slots. As time complexity of the algorithm for formation of adjacency matrix and also time complexity of BFS or DFS are non-linear, switching time will increase non-linearly with the increment of number of subscribers. In this paper a new switching algorithm is proposed which forms a distance metric, instead of adjacency matrix. It also utilizes a linear minimum selection algorithm instead of using BFS or DFS to determine the optimal input output time slots. All parts of the proposed algorithm have linear or constant time complexity. As a result, the maximum time complexity of the proposed algorithm is linear. So, switching time will increase linearly with the number of subscribers. View full abstract»

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  • On location tracking and load balancing in cellular mobile environment-a probabilistic approach

    Page(s): 121 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1004 KB) |  | HTML iconHTML  

    The present work addresses probabilistic solution of two fundamental issues of cellular mobile environment maintaining a common set of information. One of the issues is to predict the location of a mobile user whereas the other is to predict the traffic load of each area and accordingly distribute channels among different areas. For location management the entire area covered by cellular architecture is considered as a hierarchy of location areas considering mobile switching centre as the root of the hierarchy and thus a new tree like data structure is introduced. When a call arrives, mobile switching centre computes the location probability of the called mobile unit at all the cells under it with the help of a database and tree-like data structure is kept in mobile switching centre itself. Finally mobile switching centre performs the appropriate searching to find the best probable cell(s) where the desired mobile unit may be traced. The scheme is made more realistic later exploiting the fact that most of the users confine their movement within a group of cells. It is done by making leaf level of the hierarchy dynamic by switching the membership of a cell from one group to the other depending upon the change of probability of finding a user at a cell. For predicting traffic load in each cell, mobile switching centre scans the same database used for predicting the location of a mobile user and finds out frequency of locating the user in each cell. With the help of this information and a heuristic function the cell wise channel requirement is computed. Finally experiments are carried out to see the variation of system cost and delay with time considering call arrival pattern as Poisson distribution and movement pattern by Gaussian distribution. View full abstract»

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  • Performance analysis of star-tree and ring-bus millimeter-wave fiber-radio networks incorporated with cascaded WDM optical interfaces

    Page(s): 127 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1094 KB) |  | HTML iconHTML  

    The performance of wavelength-division-multiplexed (WDM) optical interfaces that support 37.5 GHz-band 25 GHz-separated wavelength-interleaved dense-WDM (WI-DWDM) signals is investigated for networks in both star-tree and ring/bus architectures. The interface offers consolidated base station (BS) architecture by enabling a wavelength reuse technique with transparent optical-add-drop-multiplexing (OADM) to the BS. The results show that the proposed interface can be a suitable candidate in future WI-DWDM mm-wave fiber-radio networks, configured in either star-tree or ring/bus architecture. View full abstract»

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  • Base transit time of a bipolar junction transistor considering majority-carrier current

    Page(s): 133 - 138
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1306 KB) |  | HTML iconHTML  

    In this paper an analytical expression for base transit time tauB for an npn bipolar transistor considering majority-carrier current density is obtained. For finding tauB, expressions for minority-carrier electron current density Jn, majority-carrier hole current density Jp and electron concentration, n(x) are analytically derived. In the model energy-bandgap-narrowing effects due to heavy doping, velocity saturation as well as doping and field dependent mobility are considered. It is found that, in the low-injection condition, tauB depends on Jp and its value is found greater than the value if Jp is neglected. In finding tauB, previous works neglected Jp. The closed-form analytical expressions offer a clear physical insight into device operations at various bias conditions. View full abstract»

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