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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Novel Convex Optimization Approaches for VLSI Floorplanning

Luo, Chaomin January 2008 (has links)
The floorplanning problem aims to arrange a set of rectangular modules on a rectangular chip area so as to optimize an appropriate measure of performance. This problem is known to be NP-hard, and is particularly challenging if the chip dimensions are fixed. Fixed-outline floorplanning is becoming increasingly important as a tool to design flows in the hierarchical design of Application Specific Integrated Circuits and System-On-Chip. Therefore, it has recently received much attention. A two-stage convex optimization methodology is proposed to solve the fixed-outline floorplanning problem. It is a global optimization problem for wirelength minimization. In the first stage, an attractor-repeller convex optimization model provides the relative positions of the modules on the floorplan. The second stage places and sizes the modules using convex optimization. Given the relative positions of the modules from the first stage, a Voronoi diagram and Delaunay triangulation method is used to obtain a planar graph and hence a relative position matrix connecting the two stages. An efficient method for generating sparse relative position matrices and an interchange-free algorithm for local improvement of the floorplan are also presented. Experimental results on the standard benchmarks MCNC and GSRC demonstrate that we obtain significant improvements on the best results in the literature. Overlap-free and deadspace-free floorplans are achieved in a fixed outline and floorplans with any specified percentage of whitespace can be produced. Most important, our method provides a greater improvement as the number of modules increases. A very important feature of our methodology is that not only do the dimensions of the floorplans in our experiments comply with the original ones provided in the GSRC benchmark, but also zero-deadspace floorplans can be obtained. Thus, our approach is able to guarantee complete area utilization in a fixed-outline situation. Our method is also applicable to area minimization in classical floorplanning.
2

Novel Convex Optimization Approaches for VLSI Floorplanning

Luo, Chaomin January 2008 (has links)
The floorplanning problem aims to arrange a set of rectangular modules on a rectangular chip area so as to optimize an appropriate measure of performance. This problem is known to be NP-hard, and is particularly challenging if the chip dimensions are fixed. Fixed-outline floorplanning is becoming increasingly important as a tool to design flows in the hierarchical design of Application Specific Integrated Circuits and System-On-Chip. Therefore, it has recently received much attention. A two-stage convex optimization methodology is proposed to solve the fixed-outline floorplanning problem. It is a global optimization problem for wirelength minimization. In the first stage, an attractor-repeller convex optimization model provides the relative positions of the modules on the floorplan. The second stage places and sizes the modules using convex optimization. Given the relative positions of the modules from the first stage, a Voronoi diagram and Delaunay triangulation method is used to obtain a planar graph and hence a relative position matrix connecting the two stages. An efficient method for generating sparse relative position matrices and an interchange-free algorithm for local improvement of the floorplan are also presented. Experimental results on the standard benchmarks MCNC and GSRC demonstrate that we obtain significant improvements on the best results in the literature. Overlap-free and deadspace-free floorplans are achieved in a fixed outline and floorplans with any specified percentage of whitespace can be produced. Most important, our method provides a greater improvement as the number of modules increases. A very important feature of our methodology is that not only do the dimensions of the floorplans in our experiments comply with the original ones provided in the GSRC benchmark, but also zero-deadspace floorplans can be obtained. Thus, our approach is able to guarantee complete area utilization in a fixed-outline situation. Our method is also applicable to area minimization in classical floorplanning.
3

Genetic Algorithm Based Design and Optimization of VLSI ASICs and Reconfigurable Hardware

Fernando, Pradeep Ruben 17 October 2008 (has links)
Rapid advances in integration technology have tremendously increased the design complexity of very large scale integrated (VLSI) circuits, necessitating robust optimization techniques in many stages of VLSI design. A genetic algorithm (GA) is a stochastic optimization technique that uses principles derived from the evolutionary process in nature. In this work, genetic algorithms are used to alleviate the hardware design process of VLSI application specific integrated circuits (ASICs) and reconfigurable hardware. VLSI ASIC design suffers from high design complexity and a large number of optimization objectives requiring hierarchical design approaches and multi-objective optimization techniques. The floorplanning stage of the design cycle becomes highly important in hierarchical design methods. In this work, a multi-objective genetic algorithm based floorplanner has been developed with novel crossover operators to address the multi-objective floorplanning problem for VLSI ASICs. The genetic floorplanner achieves significant wirelength savings (>19% on average) with little or no increase in area ( < 3% penalty) over previous floorplanners that perform simultaneous area and wirelength minimization. Hardware implementation of genetic algorithms is gaining importance because of their proven effectiveness as optimization engines for real-time applications. Earlier hardware implementations suffer from major drawbacks such as absence of GA parameter programmability, rigid pre-defined system architecture, and lack of support for multiple fitness functions. A compact IP core that implements a general purpose GA engine has been designed to realize evolvable hardware in field programmable gate array devices. The designed GA core achieved a speedup of around 5.16x over an analogous software implementation. Novel reconfigurable analog architectures have been proposed to realize extreme environment analog electronics. In this work, a digital framework has been developed to realize self reconfigurable analog arrays (SRAA) where genetic algorithms are used to evolve the required analog functionality and compensate performance degradation in extreme environments. The framework supports two methods of compensation, namely, model based lookup and genetic algorithm based compensation and is scalable in terms of the number of fitness evaluation modules. The entire framework has been implemented as a digital ASIC in a leading industrystrength silicon-on-insulator (SOI) technology to obtain high performance and a small form factor.

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