实用于CAD的小尺寸MOSFET解析模型

<正> 一、引言 SPICE电路模拟程序自用于IC的辅助设计已有十多年历史,它在IC的发展过程中起了很大作用。但随着IC向超大规模发展,过去并未能引起人们给予足够注意的,存在于MOSFET中的小尺寸效应已越来越严重,而SPICE程序中所用到的MOS模型却没有合适地考虑这些效应对器件或电路性能的影响,因此原SPICE程序已不适应于目前工艺水平下的VLSI设计工作需要,必须改进或重建所用到的MOS模型。     

The role of radiation damage on the current-voltage characteristics of p-n junctions

The effects of radiation damage on the current-voltage characteristics of silicon p-n diodes are studied. Radiation damage is introduced by the implantation of carbon ions into the depletion region of the device. The physical properties of the damage centres are examined by means of thermally stimulated current (T. S. C.) measurements, and by the measurement of the temperature dependence of the reverse leakage. The results at low implantation doses are explained by means of a single level Shockley-Read-Hall model, while at higher doses charge compensation effects are introduced. Capacitance-voltage measurements are used as a means of verifying these conclusions, and further useful data is obtained from the results of low temperature annealing experiments.     

Measurement-based simulation model for TCP over ATM

Cell level analysis of ATM networks by means of simulation requires an accurate model for traffic sources. We present a simple model for TCP over ATM traffic sources in an ATM LAN, which captures the fundamental characteristics of the behaviour of tcp in this environment. The model was developed by extensive statistical analysis of numerous traffic traces recorded in an atm testbed. Simulated traffic generated by our model has roughly the same properties as observed in real traffic, even on the time scale of milliseconds. This makes it suitable for use by the analysis of various scheduling and congestion management algorithms.     

机载光电稳定平台建模及动态特性分析

两轴两框架机载光电稳定平台以其机构简单、成本低、体积小的特点广泛应用于小型载机上.载机与光电平台之间、平台框架之间存在复杂的非线性耦合.本文根据运动学、动力学关系,采用机理建模的方法建立了包含内外框耦合力矩的数学模型,并进行了多种状态下的动态特性仿真.结果表明,当框架受扰时内框比外框更敏感,内框能更快恢复稳定.载机角速...     

A function-fit model for the hard breakdown I–V characteristics of ultra-thin oxides in MOS structures

A function-fit model for the hard breakdown current–voltage characteristics of ultra-thin oxides in metal–oxide–semiconductor structures based on the smoothing function concept is presented. The model is intended to capture the diode-like and resistance-like behaviours observed at low and high applied biases, respectively, by means of a simple, continuous and derivable function. These features make the proposed expression suited for circuit simulation environments. The effect of temperature on the model parameters is also analysed.     

光热干涉检测系统的实验参数选择

为了研究实验参数对光热干涉检测结果的影响,根据等厚干涉测量原理,利用赛德倾斜像差建立了相应的光热干涉测量模型.通过对探测光源的分析,利用随机函数建立一般性光源模型,定义了光源均匀度.在此基础上通过数值模拟,对不同光源均匀性下实验现象进行仿真,分析了光源均匀性对干涉测量结果的影响.分析表明,探测光源均匀性对热吸收干涉测量结果的影响可以忽略.同时还对比分析了不同探测器接受口径对测量结果的影响.结果显示,当探测器接收口径R=0.315cm时,在0～0.6λ的光热位移内光热信号呈单调下降,而且条纹对比度相对较大.通过曲线拟合得到在弱吸收情况下光热信号与光热位移的一个简单经验公式.     

Effects of injection resistance on the performance of very-short-channel MOSFET's

Injection resistance, the spreading resistance due to current crowding at the source end of an FET channel, can lead to considerable performance reduction in short-channel MOSFET's. A simple technique for determining the magnitude of this resistance by means of measurements in the linear operation region is described. A simple analytical model which incorporates the effects of both velocity saturation and injection resistance is also developed. The method and model are experimentally verified by determination of the effects of injection resistance on MOSFET's with channel lengths from 0.2 to 24.6 µm.     

Comparative potential performance of Si, GaAs, GaInAs, InAs submicrometer-gate FET's

For very-short-gate FET's, the nonstationary electron dynamic effects greatly improve the device performance. By means of a simple self-consistent model which takes into account the transient transport effects, a comparison between the frequency behavior of various semiconductor materials is presented. It is shown that the dynamic properties for a given material are ameliorated for greater values of the productmu_{0} Delta epsilon_{Gamma L}. Thus Ga0.47In0.53As and InAs are shown to exhibit quite interesting dynamic operating properties.     

Modeling of non-line-of-sight ultraviolet scattering channels for communication

A stochastic non-line-of-sight (NLOS) ultraviolet (UV) communication channel model is developed using a Monte Carlo simulation method based on photon tracing. The expected channel impulse response is obtained by computing photon arrival probabilities and associated propagation delay at the receiver. This method captures the multiple scattering effects of UV signal propagation in the atmosphere, and relaxes the assumptions of single scattering theory. The proposed model has a clear advantage in reliable prediction of NLOS path loss, as validated by outdoor experiments at small to medium elevation angles. A Gamma function is shown to agree well with the predicted impulse response, and this provides a simple means to determine the channel bandwidth. The developed model is employed to study the characteristics of NLOS UV scattering channels, including path loss and channel bandwidth, for a variety of scattering conditions, source wavelength, transmitter and receiver optical pointing geometries, and range.     

Sampling phase detector using a resonant tunneling high electronmobility transistor for microwave phase-locked oscillators

A novel sampling phase detector (SPD) using a resonant-tunneling high electron mobility transistor (RTHEMT), which features strong nonlinear characteristics, is proposed and demonstrated as a means of achieving a simple, low-power-consumption SPD. We confirmed promising performance for an RTHEMT as a simple pulse generator in an SPD with low power consumption, even for a low reference-signal input level. An 11-GHz phase-locked oscillator is constructed along with the present SPD, and successfully phase-locked signals are obtained with it. These results clearly show the potential of constructing high-performance analog RF circuits based on RTHEMTs     

Operation of series‐connected silicon‐based photovoltaic modules under partial shading conditions

Partial shading has been recognized as a major cause of energy losses in photovoltaic (PV) power generators. Partial shading has severe effects on the electrical characteristics of the PV power generator, because it causes multiple maximum power points (MPPs) to the power‐voltage curve. Multiple maxima complicate MPP tracking, and the tracking algorithms are often unable to detect the global maximum. Considerable amount of available electrical energy may be lost, when a local MPP with low power is tracked instead of the global MPP. In this paper, the electrical characteristics of series‐connected silicon‐based PV modules under various partial shading conditions are studied by using a Matlab/Simulink simulation model. The simulation model consists of 18 series‐connected PV modules, corresponding to a single‐phase grid‐connected PV power generator. The validity of the simulation model has been verified by experimental measurements. The voltage and power characteristics of the PV power generator have been investigated under various system shading and shading strength conditions. The results can be utilized to develop new MPP tracking algorithms and in designing, for example, building integrated PV power generators. Copyright © 2011 John Wiley & Sons, Ltd.     

Modeling and Technique to Improve PSRR and PS-IMD in Analog PWM Class-D Amplifiers

Although power-supply noise, qualified by power- supply rejection ratio (PSRR), has been recognized as a potential drawback of Class-D amplifiers (CDAs) compared to linear amplifiers, the mechanisms of PSRR for CDAs are not well established. It is also not well recognized that the power-supply noise can intermodulate with the input signal, manifesting into power-supply induced intermodulation distortion (PS-IMD), and that the PS-IMD can be significantly larger than the output distortion component at supply noise frequency. Furthermore, techniques to improve PSRR and PS-IMD are largely unreported in literature. In this brief, by means of a linear model, the PSRR and PS-IMD of single-feedback and double-feedback CDAs are analyzed and analytical expressions derived. A simple method is proposed to improve PSRR and PS-IMD with very low hardware overheads, and the improvement is ~ 26 dB. Analytical expressions for PSRR and PS-IMD of the improved design are derived and the pertinent parameters thereof are investigated. The model and analyses provide practical insight to the mechanisms of PSRR and PS-IMD, and how various parameters may be varied to meet a given specification.     

Analysis of Millimeter Wave Varactor-Tuned Gunn Oscillator Stabilized with a Transmission Cavity

A novel circuit architecture which describes millimeter wave varactor-tuned Gunn oscillator stabilized with a transmission cavity has been proposed in this paper. A corresponding equivalent circuit model has been presented in order to study its performance characteristics. The circuit model consists of four parts which are varactor cavity, main cavity, transmission waveguide and transmission cavity. Based upon this model, electrical tuning characteristics have been studied at first. Mode jumping problems during electrical tuning process have been analyzed qualitatively. Moreover, quality factor and efficiency of the circuit model have been derived by virtue of relevant circuit parameters. The effects of some important circuit parameters affecting circuit performance parameters have been discussed. The circuit model can describe the circuit architecture accurately and effectively. This circuit architecture, which can generate signals exhibiting low frequency modulation noise, high frequency stabilization and electrical tunable characteristics, is applicable to various practical situations.     

Comparison of electrical drives for road vehicles

The low storage capacity of presently available galvanic batteries restricts the effective use of electrically driven vehicles to a limited range of transportation jobs. For this application any change from vehicles driven by internal combustion engines to vehicles driven by electric motors can only be justified if the use of electrical drives results in an overall cost reduction. This criterion means that a direct current, separately excited motor with its speed controlled by field weakening is the best solution. In a conventionally designed motor the attainable speed range is limited to approximately 1:3. In most cases additional means for the extension of the driving range are required. If, however, the motor is equipped with an additional compensation winding, a controllable speed range of close to 1:8 is obtainable by field weakening. Acceleration characteristics are applied to evaluate the various drive units which provide advantages in energy consumption and disadvantages in the acceleration time, and vice versa. On the basis of test vehicles with various drive systems, design of the required control is explained. Additional requirements for automatic control are partially offset by the additional protective devices required to restrict the effects of faulty handling of a manually controlled drive.     

Numerical analysis on compliance and electrical behavior of multi-copper-column flip-chip interconnects for wafer-level packaging

This paper presents modeling and simulation results of a modified copper-column-based flip-chip interconnect with ultrafine pitch for wafer-level packaging, and the process and prototyping procedure are described as well. This interconnect consists of multiple copper columns which are electrically in parallel and supporting a solder bump. A simple analytical model has been developed for correlation between the interconnect geometry and the thermal fatigue life. In comparison to the conventional single-copper-column (SCC) interconnects, numerical analysis reveals that the multi-copper-column (MCC) interconnect features enhanced compliances and, hence, higher thermomechanical reliability, while the associated electrical parasitics (R, L, and C) at dc and moderate frequencies are still kept low. Parametric studies reveal the effects of geometric parameters of MCC interconnects on both compliances and electrical parasitics, which in turn facilitate design optimization for best performance. By using coplanar waveguides (CPWs) as feed lines on both chip and package substrate, a high-frequency (up to 40 GHz) S-parameter analysis is conducted to investigate the transmission characteristics of the MCC interconnects within various scenarios which combines various interconnect pitches and common chip and package substrates. An equivalent lumped circuit model is proposed and the circuit parameters (R, L, C, and G) are obtained throughout a broad frequency range. Good agreement is achieved for the transmission characteristics between the equivalent lumped circuit model and direct simulation results.     

A Carrier-Transit-Delay-Based Nonquasi-Static MOSFET Model for Circuit Simulation and Its Application to Harmonic Distortion Analysis

In this paper, a compact model of nonquasi-static (NQS) carrier-transport effects in MOSFETs is reported, which takes into account the carrier-response delay to form the channel. The NQS model, as implemented in the surface-potential-based MOSFET Hiroshima University STARC IGFET model, is verified to predict the correct transient terminal currents and to achieve a stable circuit simulation. Simulation results show that the NQS model can even reduce the circuit simulation time in some cases due to the elimination of unphysical overshoot peaks normally calculated by a QS-model. An average additional computational cost of only 3% is demonstrated for common test circuits. Furthermore, harmonic distortion characteristics are investigated using the developed NQS model. While the distortion characteristics at low drain bias and low switching frequency are determined mainly by carrier mobility, distortion characteristics at high frequency are found to be strongly influenced by channel charging/discharging.     

Corner-parasitics-free low-cost trench isolation

In this work, we present results on a novel low-cost, corner-parasitics-free trench isolation process. Regarding process complexity, this approach is almost as simple as LOGOS isolation, since the isolation oxide is deposited selectively within the trench. Due to the self-planarizing nature of the fill oxide, the global planarization sequence is largely simplified. With respect to scalability, this approach offers all the advantages of trench isolation with its abrupt transition of active area to isolation. However, in contrast to previous trench isolation schemes, corner-parasitic effects are eliminated by means of the extended trench isolation gate technology (EXTIGATE) device geometry. As a result, excellent narrow width characteristics and subthreshold curves without kink effect are obtained     

Tensile strain and threshold currents in GaAsP-AlGaAssingle-quantum-well lasers

The effects of tensile strain on threshold current in GaAsP-AlGaAs quantum well lasers are studied theoretically and experimentally. A comprehensive model for the light-current characteristics of separate-confinement strained-layer lasers, which is based on a six-band Luttinger-Kohn valence dispersion model, is first developed. Theoretical and experimental results for broad stripe single-well laser diodes with a constant well width of 115 Å are then presented. Experimentally observed variations in threshold currents and TE/TM polarization switching are accurately described by the model for phosphorus compositions in the quantum-well ranging from 0 to 0.30 and cavity lengths ranging from 300 to 1500 μm. Constant-gain contours generated from the theoretical model are shown to provide a simple and powerful guide to various regimes of operation. Our studies show that tensile-strain-related effects lower threshold currents in GaAsP-AlGaAs only in the high gain (short cavity) regime, and suggest more generally that the threshold advantages offered by tensile strain are conditional