35282259
New algorithms for circuit simulation of device breakdown
Numerical algorithms that enable extension of device models into avalanche breakdown region without disturbing the convergence of modified nodal-analysis-based circuit simulators are introduced. Details of model implementation into circuit simulators are presented along with applications. In particular, circuit-level simulation of nondestructive electrostatic discharge phenomena is discussed along with the time-step size on the simulation of negative resistance structures. >
44275614
Cell-level placement for improving substrate thermal distribution
The dramatic increase of power consumption in very large scale integration circuits has led to high operating temperature and large thermal gradient, thereby resulting in serious timing and reliability concerns. Temperature-tracking is thus becoming of paramount importance in modern electronic design automation (EDA) tools. In this paper we present two thermal placement tools for standard cell and macro cell design styles respectively. They are aimed at reducing hot spots in a design without compromising traditional design metrics such as area and wire length. We developed a compact substrate thermal model that can be used by the placer to calculate the temperature profile of a placement efficiently, or to convert the user-specified temperature constraint into the corresponding power distribution constraint as an alternative placement objective. As a result, our method is much more efficient than directly employing temperature profile simulation during the placement process. The simulation results show noticeable improvement of thermal distribution over the traditional placement algorithm, with little impact on area and wire length of the final layout.
5129503
Detailed layer assignment for MCM routing
A new routing environment model, called the k-MCM model, is developed to take into account the unique features of a multilayer MCM, such as the availability of “segmented vias” , and the presence of two “active” or terminal-bearing layers. A detailed layer assignment problem is formulated on the k-MCM model. A fast heuristic algorithm for the layer assignment problem is proposed. and experimental results on twelve test examples with net counts up to 842 are presented.
40491047
Domino logic synthesis based on implication graph
In this paper, we present a new approach to the problem of inverter elimination in domino logic synthesis. A small piece of static CMOS logic is introduced to the circuit to avoid significant area penalty resulting from duplication. To maximize the domino logic part and to minimize the static CMOS logic part, a generalized automatic test pattern generation (ATPG)-based logic transformation is proposed to eliminate or relocate a target inverter. Based on the new concept of dominating set of mandatory assignment (DSMA) and the corresponding implication graph, we propose algorithms to identify a minimum candidate set for a target inverter. Experimental results show that logic transformation based on the implication graph can reduce transistor counts by 25% on average, while the delay increases less than 3%.
13489029
An integrated approach to realistic worst-case design optimization of MOS analog circuits
The authors present a new integrated approach for the optimization of MOS analog circuit performance by using realistic worst-case device parameter files, each corresponding to a performance measure. Nonlinear response surfaces are constructed for the performance measures of interest, and the worst-case device parameter files are identified by solving a set of suitably cast nonlinear programming problems. The worst-case files are shown to depend on the values of the designable parameters. An efficient method of incorporating this dependence during worst-case design optimization has been developed. This method enables the design of circuits with optimal performance and high parametric yields. Some illustrative analog circuit examples are given to demonstrate the application of the worst-case design optimization procedure.<<ETX>>
13548202
Noise constrained power optimization for dual V/sub T/ domino logic
In dual threshold voltage techniques, significant subthreshold leakage current is one of the most important design problems. When dual threshold voltage is applied to the domino logic, noise immunity has to be carefully considered because the significant subthreshold current makes dynamic nodes much more susceptible to noise. In this paper, an analytical model for proper keeper transistor sizing to meet noise constraint is presented. Based on the same noise constraint, we propose dual threshold voltage domino logic technique to save power consumption.
17171711
Characterization of errors in compositing panoramic images
In this paper we describe the effect of errors in the intrinsic camera parameters on reconstructed panoramic images. A panoramic image is created by first capturing a sequence of images while rotating the camera about a vertical axis a full 360/spl deg/. The subsequent steps are projecting the original rectilinear images onto cylindrical surfaces and compositing them to form the panoramic image. Our analysis has led to a technique that allows simultaneous recovery of the camera focal length and properly composited panoramic images. The correct focal length can be determined by iterating the processes of projecting the original rectilinear images onto cylindrical surfaces given an estimate of the focal length and compositing the resulting images to yield an increasingly better estimate of the focal length. This paper shows that the convergence towards the correct focal length is exponential.
16190492
Noise Estimation from a Single Image
In order to work well, many computer vision algorithms require that their parameters be adjusted according to the image noise level, making it an important quantity to estimate. We show how to estimate an upper bound on the noise level from a single image based on a piecewise smooth image prior model and measured CCD camera response functions. We also learn the space of noise level functions how noise level changes with respect to brightness and use Bayesian MAP inference to infer the noise level function from a single image. We illustrate the utility of this noise estimation for two algorithms: edge detection and featurepreserving smoothing through bilateral filtering. For a variety of different noise levels, we obtain good results for both these algorithms with no user-specified inputs.
1332259
On the Motion and Appearance of Specularities in Image Sequences
Real scenes are full of specularities (highlights and reflections), and yet most vision algorithms ignore them. In order to capture the appearance of realistic scenes, we need to model specularities as separate layers. In this paper, we study the behavior of specularities in static scenes as the camera moves, and describe their dependence on varying surface geometry, orientation, and scene point and camera locations. For a rectilinear camera motion with constant velocity, we study how the specular motion deviates from a straight trajectory (disparity deviation) and how much it violates the epipolar constraint (epipolar deviation). Surprisingly, for surfaces that are convex or not highly undulating, these deviations are usually quite small. We also study the appearance of specularities, i.e., how they interact with the body reflection, and with the usual occlusion ordering constraints applicable to diffuse opaque layers. We present a taxonomy of specularities based on their photometric properties as a guide for designing separation techniques. Finally, we propose a technique to extract specularities as a separate layer, and demonstrate it using an image sequence of a complex scene.
26233543
Appearance-Based Structure from Motion Using Linear Classes of 3-D Models
In this paper, we address the problem of recovering 3-D models from sequences of partly calibrated images with unknown correspondence. To that end, we integrate tracking, structure from motion with geometric constraints (specifically in the form of linear class models) in a single framework. The key to making the proposed approach work is the use of appearance-based model matching and refinement which updates the estimated correspondences on each iteration of the algorithm. Another key feature is the matching of a 3-D model directly with the input images without the conventional 2-step approach of stereo data recovery and 3-D model fitting. Initialization of the linear class model to one of the input images (the reference image) is currently partly manual.This synthesis and refine approach, or appearance-based constrained structure from motion (AbCSfm), is especially useful in recovering shapes of objects whose general structureis known but which may have little discernable texture in significant parts of their surfaces. We applied the proposed approach to 3-D face modeling from multiple images to create new 3-D faces for DECface, a synthetic talking head developed at Cambridge Research Laboratory, Digital Equipment Corporation. The DECface model comprises a collection of 3-D triangular and rectangular facets, with nodes as vertices. In recovering the DECface model, we assume that the sequence of images is taken with a camera with unknown focal length and pose. The geometric constraints used are of the form of linear combination of prototypes of 3-D faces of real people. Results of this approach show its good convergence properties and its robustness against cluttered backgrounds.
205396452
Video dejittering by bake and shake
Video jittering occurs when the horizontal lines of video image frames are randomly displaced due to the corruption of synchronization signals or electromagnetic interference during video transmission. Inspired by the recent Bayesian/variational dejittering model of Shen (SIAM J. Appl. Math., vol. 64, pp. 1691-1708, 2004), in the current paper we propose a novel dejittering approach nicknamed 'bake-and-shake.' The bake step is to apply Perona-Malik type nonlinear diffusions to 'melt away' or heat up the jittered video frames, based upon which the shake step is able to optimally estimate the individual line jitters and renormalize the jittered images. Numerical implementation of the bake-and-shake algorithm as well as several computational results are presented.