A layout-based schematic method for very high-speed CMOS celldesign

In very high-speed CMOS cell design, the result of schematic simulation is inaccurate because of missing parasitic components, such as diodes and parasitic capacitances. Designer cannot pass enough information to the simulator by conventional transistor symbols, therefore, simulation error occurs. In this paper, we address a layout-based schematic (LBS) method for high-speed CMOS cell design. In this method, we introduce several types of MOS transistors and estimate parasitic wire capacitances by using layout knowledge. The simulation results show that the difference between LBS and real layout is much smaller, less than 3% in rise time, compared to in the worst case of up to 65% in the original schematic. This method can be applied to both digital and analog circuits and it is helpful for layout automation. Time and cost will be reduced in high-speed circuit design     

A systematic procedure for scaling wave digital filters

This paper describes a systematic procedure for scaling wave digital filters to avoid overflow problems and at the same time maximizing the output signal-to-noise ratio. Examples are included to illustrate the procedure.     

A new scaling length for modeling semiconductor space-charge regions

Intrinsic and extrinsic Debye lengths have been extensively used in device modeling work. Recently Jindal and Warner [4], using extrinsic Debye length, have developed a unified solution applicable to all step junctions. They have further extended it to include the semiconductor surface problem [5]. As a result of these general analyses, the role of extrinsic Debye length in distance normalization in cases where mobile charges are dominant has been more clearly understood. A new scaling length, whose use is complementary to that of extrinsic Debye length is proposed for cases where fixed charge is dominant.     

A method for modeling array elements when using NEC and MININEC

This paper distinguishes between the active and passive states of an array element and advances the thesis that models defined in the passive state maintain their validity in the active state. The influence of reactance at the base of an array element is demonstrated and analytical expressions are suggested to aid in quantifying the base reactance. A model architecture is proposed together with methods for determining the model parameters. Examples of both analysis and design are included and the results are compared to measured data     

A systematic modeling theory for solid state devices

A theory is formulated for systematically modeling solid state devices from physical make-up. The theory consists of three general guidelines for deriving desired models and four explicit approaches for implementing the guidelines. The guidelines and approaches are stated in general terms to enhance the applicability of the theory to a broad range of different devices.Models which are derived by application of this theory (1) involve component parts which are explicit functions of the physical construction and which exhibit a one-to-one correspondence with physical processes, (2) are amenable to the techniques of network analysis and network synthesis and (3) involve a degree of approximation sufficient to enhance qualitative understanding while maintaining desired quantitative accuracy. The models thus can serve as tools for the analysis and design of both circuits and devices.Several important aspects of the theory are illustrated by applying it to the diffusion transistor and the field-effect transistor. Models obtained for the diffusion transistor are related to, though more general than, those published previously; models obtained for the field-effect transistor are new.     

A moment method approach using frequency-independent parametricmeshes

A moment method (MM) formulation using nonuniform rational B-splines (NURBS) parametric surfaces is introduced to analyze radiation and scattering from arbitrarily shaped conducting bodies. A feature of the technique presented is the independence of the geometrical model from the frequency which avoids the regeneration of the geometry model when the frequency changes. This feature is obtained by defining new sets of basis and testing functions that extend over subpatches in each NURBS. The proposed approach is accurate, flexible, and efficient     

A modeling approach for burn scar assessment using natural features and elastic property

A modeling approach is presented for quantitative burn scar assessment. Emphases are given to: 1) constructing a finite-element model from natural image features with an adaptive mesh and 2) quantifying the Young's modulus of scars using the finite-element model and regularization method. A set of natural point features is extracted from the images of burn patients. A Delaunay triangle mesh is then generated that adapts to the point features. A three-dimensional finite-element model is built on top of the mesh with the aid of range images providing the depth information. The Young's modulus of scars is quantified with a simplified regularization functional, assuming that the knowledge of the scar's geometry is available. The consistency between the relative elasticity index and the physician's rating based on the Vancouver scale (a relative scale used to rate burn scars) indicates that the proposed modeling approach has high potential for image-based quantitative burn scar assessment.     

小波在多孤子相互作用数值研究中的应用

给出了研究多孤子在单模光纤中传播时相互作用的一种新的数值方法。它是基于导函数属于Ｈｉｌｌｂｅｒｔ 空间和Ｓｏｂｏｌｅｖ 空间中的基在Ｌ２ 范数意义下与Ｌ２（Ｉ） 空间的基的一致性,即在Ｓｏｂｏｌｅｖ 空间构造的小波基就是Ｌ２（Ｉ） 空间的小波基,从而可以导出用小波表示的导算子,并将它作用在非线性Ｓｃｈｒｏｄｉｎｇｅｒ 方程中的时间变量上, 得到一个新的迭代方程。用这种方法得到的结果与有关文献的一致,从而证明了其有效性     

A systematic and unified approach to modeling PWM DC/DC convertersbased on the graft scheme

A systematic and unified approach to modeling pulsewidth modulated (PWM) DC/DC converters based on the graft scheme is presented in this paper. With the graft scheme, the typical PWM switch-mode converters, such as buck-boost, boost-buck (Cuk), Sepic, and dual Sepic, can be generated from the two basic converters, buck and boost. The small signal models of these converters can, therefore, be derived by properly combining those of the buck and boost. Using the proposed approach can help to yield highly related dynamic models of the converters in a family and, in addition, physical insights into the converters can be readily identified. This has made the proposed modeling method valuable and viable     

A systematic controller-design approach for neutral-point-clamped three-level inverters

This paper proposes a simple linear feedback-based control technique that ensures zero-neutral-point (NP) potential in three-level voltage-source inverters. The technique works even under dynamic load conditions and enables the decoupled control of the direct and in-quadrature load currents. The technique is based on the relative-gain-array (RGA) approach, which has been successfully used in the control of chemical-engineering processes. The resulting scheme allows the use of outer control loops to set the direct and in-quadrature load currents as required for the specific application (e.g., adjustable speed drives). Experimental results prove the theoretical considerations and show the simplicity of the proposed control scheme.     

A thin-rod approximation for the improved modeling of bare and insulated cylindrical antennas using the FDTD method

A general and consistent integral finite-difference time-domain (FDTD) formulation on cubical grids for modeling of cylindrical antennas with or without dielectric coating is derived. No additional grid points or modifications of the integral paths are necessary. Instead, effective material properties are modified in the FDTD grid. Thus, even for insulated antennas, the simple cubical structure is maintained. Special integral factors are defined on cubical elements, which take into account the behavior of fields in all directions in the neighborhood of the antenna. Applying these factors to the gap region and along the antenna's axis allows a correct modeling of the influence of the antenna's thickness. Furthermore, integral factors derived for the antenna's ends improve the modeling of the antenna's length. The accuracy of the method is confirmed by a systematic comparison with analytical and numerical results.     

A computer modeling approach for LSI digital structures

The paper presents a novel modeling approach to LSI MOST circuits performed at the gate level. A macromodel is analytically derived and provides a direct relationship between the input function and output response of the gate. This approach or macromodeling has been implemented for over 10 000 devices in LSI with only 32K of computer core and very fast computing time. The method employed relates directly the performance parameters (e.g., turn-on voltage, rise, and fall times, etc.) to the device parameters. An insight into the propagation delay of LSI structures is gained by statistically studying the transient performance of the system using Monte-Carlo techniques. Experimental results give ample evidence of good agreement with the computed results, for which various values of x0, oxide thickness, are used.     

A GACS modeling approach for MPEG broadcast video

Accurate MPEG source models are needed to support high speed networks such as ATM and Internet. In this paper, we propose a video model called Gaussian auto-regressive and chi-square processes (GACS) for MPEG coded video traffic. The GACS models the sizes of MPEG I, P, and B frames according to the MPEG syntax I-frame>P-frame>B-frame. This is done by decomposing the process of each frame size into a weighted sum of a number of chi-square sequences. Each chi-square sequence is then obtained by squaring a Gaussian process, which is efficiently generated by using an auto-regressive (AR) model whose parameters are determined from an estimated covariance matrix. We evaluate the effectiveness of our model by conducting a series of experiments using a wide variety of long empirical video sequences. The results show that the proposed model leads to excellent data fit and accurate prediction of queuing performance.     

A simple method for solving the LQG stochastic control problem using a polynomial approach

The paper presents a simple method for solving the optimal (LQG) control problem on an infinite time horizon for linear plants described by proper rational transfer function matrices. Since the class of proper plants discussed in the paper is more general than the one commonly used, additional properties of solutions are presented. Two numerical examples illustrate the theoretical considerations. The examples have been performed on an IBM PC using the proposed algorithm. This algorithm is a part of a public ASMCS package developed by the author for analysis, synthesis, and simulations of multi-input, multi-output (MIMO) control systems.This work was partially supported by the Polish Ministry of National Education under Grant DNS-T/02/085/90-2 and by the Polish Scientific Research Committee under Grant No. 45-0105/14-05.     

A new approach to the modeling of converters for SPICE simulation

An approach to the modeling of DC-DC converters for SPICE simulation is developed in which the average current in the energy-storage inductor is first simulated in a SPICE subcircuit for both the continuous and discontinuous modes of operation. The inductor current is then weighted and redistributed to related branches of the circuit to simulate the average input and output currents of the converter. Based on this technique, various converter models, including that of the Cuk converter with coupled inductors, which are valid for both continuous and discontinuous modes of operation, are developed     

Robust controller for a full-bridge rectifier using the IDA approach and GSSA modeling

An interconnection-and-damping assignment passivity-based control (IDA-PBC) for a full-bridge rectifier is presented in this paper. The closed-loop system performance fulfils unity power factor in the ac mains and output dc voltage regulation. The controller design takes advantage of the generalized state space averaging (GSSA) modeling technique to convert the quoted nonstandard problem (in actual variables) into a standard regulation one (in GSSA variables). In this approach, the output current is the measured signal instead of the line current; therefore, the number of sensors does not increase in comparison with traditional approaches. The whole system is robust with respect to load variations.     

A hybrid modeling method for mechanical systems

In this paper, a system identification method for hybrid systems switched by the magnitude of velocity and displacement is proposed. First, it is shown that the regression vector space of a mechanical system switched by the magnitude of velocity cannot be separated by a hyperplane. Then a method based on support vector machines with a polynomial kernel is proposed. The effectiveness of the proposed method is shown by simulations and experiments.