A physically based,accurate compact model of direct tunneling gate current considering quantum mechanical effects in nanoscale metal‐oxide‐semiconductor field‐effect transistors

We present a physically based, accurate model of the direct tunneling gate current of nanoscale metal‐oxide‐semiconductor field‐effect transistors considering quantum mechanical effects. Effect of wave function penetration into the gate dielectric is also incorporated. When electrons tunnel from the metal oxide semiconductor inversion layer to the gate, the eigenenergies of the quasi‐bound states turn out to be complex quantities. The imaginary part of these complex eigenenergies, Γ_ij, are required to estimate the finite lifetimes of these states. We present an empirical equation of Γ_ij as a function of surface potential. Inversion layer electron concentration is determined using eigenenergies, calculated by modified Airy function approximation. Hence, a compact model of direct tunneling gate current is proposed using a novel approach. Good agreement of the proposed compact model with self‐consistent numerical simulator and published experimental data for a wide range of substrate doping densities and oxide thicknesses states the accuracy and robustness of the proposed model. The proposed model can well be extended for devices with high‐κ/stack gate dielectrics introducing necessary modifications. Copyright © 2011 John Wiley & Sons, Ltd.     

A drain current model for Schottky-barrier CNT-FETs

We present here a physics-based drain current model for Schottky-barrier carbon nanotube field-effect transistors. The model captures a number of features exhibited by these transistors such as thermionic and tunnel emission, ambipolar conduction, ballistic transport, multimode propagation and electrostatics dominated by the nanotube capacitance     

A dc model for partially depleted SOI laterally diffused MOSFETs utilizing the HiSIM-HV compact model

This paper presents a subcircuit compact model to study the dc characteristics of a partially depleted (PD) SOI laterally diffused metal oxide semiconductor field effect transistor (LDMOSFET) utilizing the HiSIM-HV compact model. Our model accounts both for the high-voltage and the floating-body effects such as the quasi saturation effect, the impact ionization in the drift region and the famous kink effect. The high-voltage effects, due to the surface MOS region of PD SOI LDMOSFET, are modeled using the HiSIM-HV model. The HiSIM-HV model, a surface-potential-based compact model, is used as a baseline model as it determines the potential consistently in the complete PD SOI LDMOSFET. And, to incorporate the floating-body effects into the HiSIM-HV model, we have used the same approach as used in developing BSIMSOI model. It is shown that to model the floating-body effects, mainly the kink in the output characteristics, the current due to the impact ionization in the drift region (I _KIRK ) needs to be accurately modeled. An external current controlled current source (CCCS) is included in the proposed subcircuit model to model I _KIRK accurately. The model is validated for a set of channel and drift lengths to demonstrate the scalability of the model. The accuracy of the proposed subcircuit model is verified using 2-D numerical simulations.     

Modeling of tunneling current and gate dielectric reliability for nonvolatile memory devices

We present a hierarchy of tunneling models suitable for the two- and three-dimensional simulation of logic and nonvolatile semiconductor memory devices. The crucial modeling topics are comprehensively discussed, namely, the modeling of the energy distribution function in the channel to account for hot-carrier tunneling, the calculation of the transmission coefficient of single and layered dielectrics, the influence of quasi-bound states in the inversion layer, the modeling of static and transient defect-assisted tunneling, and the modeling of dielectric degradation and breakdown. We propose a set of models to link the gate leakage to the creation of traps in the dielectric layer, the threshold voltage shift, and eventual dielectric breakdown. The simulation results are compared to commonly used compact models and measurements of logic and nonvolatile memory devices.     

NPC结构型SVG的模型预测电流控制策略

针对中点钳位型(neutral point clamped,NPC)的静止无功发生器(static var generator,SVG),提出了一种模型预测电流控制策略.由于SVG的预测模型实际上是一种开环模型,故其交流侧实际输出电流与指令电流存在电流跟踪误差,在平衡计算量与跟踪精度的前提下,设计了电流跟踪精度误差的评...     

Electrothermal compact model of CoolSET voltage regulators for SPICE

This paper concerns the problem of modelling CoolSET voltage regulators with self‐heating taken into account. The limits of the model of this class of regulators developed by Infineon Technologies AG were analysed. A new electrothermal model of CoolSET regulators designed to analyse transient in the SPICE software was proposed. The correctness of the elaborated model was verified on the example of boost and flyback converters. A good agreement of the measurement and calculation results carried out with the use of a new model was achieved. Copyright © 2007 John Wiley & Sons, Ltd.     

双极性电堆中漏电电流简化计算模型

在试验基础上,定性分析了各因素对漏电电流的影响;在解释漏电电流产生机理的同时,提出简化计算模型,并通过试验对模型进行了验证.得到结论如下:在支路电阻R较大时,单体数为N的双极性电堆,第n个单体的漏电电流jn=(N-2n+1)E/2R;第n个单体和第n+1个单体间的电流损耗为:ln=(nN- n2)E/2R(n＜N).     

High-grade position estimation for SRM drives using fluxlinkage/current correction model

This paper proposes a principle of high-resolution sensorless position estimation for a switched reluctance motor (SRM) drive, using either flux linkage or current to correct for errors in rotor position. The estimation algorithm makes full use of the nonlinear magnetic characteristics of the SRM through correlation of current, flux linkage and rotor position. The estimation model is simple, but with no loss in accuracy, leading to few real-time computations. Furthermore, a criterion is proposed to choose the phase most suited for position estimation when more than one phase conducts. The algorithm can also correct the predicted flux linkage, which, in turn, may be used to further correct the position estimate, and the features hereof are discussed. Simulations, real-time implementation and experimental results using the algorithm are presented, and confirm the concept     

Physically based 2D compact model for power bipolar devices

The two‐dimensional (2D) physical compact model for advanced power bipolar devices such as injection enhanced gate transistor (IEGT) or Trench IGBT is presented in this paper. In order to model the complex 2D nature of these devices the ambipolar diffusion equation has been solved simultaneously for different boundary conditions associated with different areas of the device. The IEGT compact model has been incorporated into the SABER simulator and tested in standard double‐pulse switching test circuit. The compact model has been established to model a 4500V‐1500A flat pack TOSHIBA IEGT. Copyright © 2004 John Wiley & Sons, Ltd.     

基于隧道磁电阻效应的宽频带电流无线测量装置

宽频带电气量数据包含大量故障暂态信息,传统互感器带宽受限难以精确全面地测量宽频暂态信号。针对该问题,提出一种含精确时标的非侵入式电流测量方法并设计原理样机。通过隧道磁电阻(TMR)芯片测量线路电流感生磁场,根据被测导体与TMR传感器的相对位置计算变比并通过微处理器进行录波和读数。设计低噪声、可变增益的传感器模组电路和暂态录波无线测量传输模组电路,精确感知宽频信号;根据传感器实际安装位置推导传变关系式,实现对一次电流的精确计算。搭建测试平台对测量装置直流、交流及暂态信号传变能力开展测试,在10 kV配电网进行接地故障电流测量对比实验。分析了影响磁阻传感器测量精度的主要因素,结果表明其直流和工频信号测量误差小于1%,高频信号测量误差小于3%。     

Two-trap-assisted tunneling model for post-breakdown I-V characteristics in ultrathin silicon dioxide

This paper investigated the degradation and breakdown characteristics of an ultrathin silicon dioxide film by using conductive atomic force microscopy (C-AFM) with repetitive ramped voltage stress (RVS). Two-step oxide degradation was determined from the measured current-voltage (I-V) characteristics and topographies. In the first step, bond breaking and negative-charge accumulation near the SiO/sub 2//Si interface causes oxide thinning and an effective increase in SiO/sub 2//Si barrier height. In this step, hard breakdown (HBD) actually does not occur until permanent damage is produced within the oxide during the second step after several times of repetitive RVS. The permanent damage produced inside the oxide film is in the form of traps, which will cause the crooked I-V curves and a larger I-V shift along the voltage axis. A two-trap-assisted tunneling (TTAT) model was proposed to explain the postbreakdown I-V behaviors. In this model, two isolated traps were generated in the oxide after breakdown. The trap location of the nearer traps determines the bending of the postbreakdown I-V curves and that of the farther traps causes the I-V oxide voltage shift along the voltage axis. The model fits the measured postbreakdown I-V curves well when the locations of both the nearer trap and the farther trap are chosen correctly.     

A surface-potential based drain current model for short-channel symmetric double-gate junctionless transistor

Junctionless transistors, which do not have any pn junction in the source-channel-drain path have become an attractive candidate in sub-20 nm regime. They have homogeneous and uniform doping in source-channel-drain region. Despite some similarities with conventional MOSFETs, the charge-potential relationship is quite different in a junctionless transistor, due to its different operational principle. In this report, models for potential and drain current are formulated for shorter channel symmetric double-gate junctionless transistor (DGJLT). The potential model is derived from two dimensional Poisson’s equation using “variable separation technique”. The developed model captures the physics in all regions of device operation i.e., depletion to accumulation region without any fitting parameter. The model is valid for a range of channel doping concentrations, channel thickness and channel length. Threshold voltage and drain-induced barrier lowering values are extracted from the potential model. The model is in good agreement with professional TCAD simulation results.     

A step-up/step-down direct current to direct current converter for high-power,high-current applications

This work proposes the conception of a nonisolated direct current (DC)-DC buck-boost converter employing the three-state switching cell. Similarly to interleaving, it is possible to achieve higher power levels than that regarding the classical buck-boost converter, but prominent advantages over the interleaved approach result, ie, the input current is continuous for duty ratios higher than 0.5; good current sharing is achieved without the need of special control schemes; and the active switches are connected to the same reference node as the input voltage source, as there is no need to use isolated drive circuitry. A thorough quantitative and qualitative analysis is carried for the entire range of the duty cycle D, considering that the proposed converter presents distinct behaviors for D < 0.5 and D > 0.5. An experimental prototype is developed and evaluated, while the results are discussed in detail.     

A compact 2D potential model for subthreshold characterization of nanoscale fully depleted short channel nanowire MOSFETs

In this work, a compact subthreshold model for fully depleted nanoscale short channel nanowire MOSFETs is proposed. It is based on an approximated solution of two‐dimensional Poisson's Equation in cylindrical coordinate system. It matches well with technology computer‐aided design simulation results in a wide range variation of design parameters without introducing any empirical fitting parameters. Copyright © 2014 John Wiley & Sons, Ltd.     

Unified analytical treatment for the current flow due to tunneling of electrons from metal into semiconductor

By the use of binomial expansion theorem the analytical treatments for the current flow due to tunneling of electron from the metal into the semiconductor are established. The obtained formulas can be useful in the analytical evaluation of the current density from the semiconductors to the metals. The method is general and easy for application. Numerical tests show that the obtained formulas provide higher accuracy and efficiency than the approximation methods in literature. The usefulness of the suggested method is confirmed by the concrete example.     

A simple model for a thyristor-driven DC motor consideringcontinuous and discontinuous current modes

A simple model for a thyristor driven DC motor is rigorously established. The derivation is based on the machine equations and on the definition of a pseudoinstantaneous mean-value function. The influence of the converter on the voltage applied to the DC motor is considered. The final model includes all significant effects, has the same structure for continuous and discontinuous current conduction modes, and allows simple control synthesis. The model is compared to the classical model of a DC motor, and the differences are highlighted. It is shown that, with the proposed model, it it easy to understand the influence of a thyristor converter on the dynamic performance of a DC motor, and, therefore, it has a significant educational aspect. A dual-mode adaptive current controller is designed using this model. Experimental and simulation results are compared to validate the work     

A compact integrated visual motion sensor for ITS applications

We have developed a prototype of a compact integrated visual sensor which detects direction and velocity of motion on a focal plane in a wide brightness range in real time with a newly devised motion measurement method. The sensor is composed of a lens and a single-chip very large scale integration whose die size is 2 mm /spl times/ 2 mm that was fabricated with a 1.5-/spl mu/ standard CMOS process. The spatial resolution is 10 /spl times/ 2. As a result of performance evaluation of the prototype sensor, it was confirmed that the sensor can detect motion direction and velocity up to an on-chip image velocity of 100 mm/s in a response time of 10 /spl mu/s under an illuminance range between 100 and 100,000 lux. Furthermore, we have demonstrated effectiveness of the visual sensor by applying the sensor to running vehicle detection on a road and blind-corner monitoring at a road junction.     

A superconducting magnet for a compact synchrotron radiation ring

A 180‐degree superconducting bending magnet for a synchrotron radiation source has been designed and constructed based on three‐dimensional electromagnetic analysis. The magnet is covered by an iron shield to prevent the leakage of magnetic fields. The liquid helium consumption of the equipment is very small in the persistent current mode. The results of the analysis are in good agreement with measured results. This magnet operates as a synchrotron radiation source at a beam energy of 600 MeV. The radiation source can be used for several applications, such as X‐ray lithography, in the semiconductor industry. © 1998 Scripta Technica, Electr Eng Jpn, 126(1): 61–69, 1999     

基于动量因子的神经网络群电流负荷预测模型

通过建立改进的4层神经网络群,以历史负荷电流作为样本进行训练,实现对于未来负荷电流的预测。针对传统BP神经网络易收敛到局部极值的问题,引入了动态调整的动量因子。为增强对于随月份动态变化较剧烈的负荷的预测能力,提出了BP网络群结构。数据模拟结果说明该算法具有高精确性,可有效估算出下一阶段线路电流负荷变化趋势值,并且预测速度满足实际使用要求。该模型可以用于监测重点单位用电负荷变化情况,及早提示供电单位采取相应措施,促进智能电网建设。