Other affiliations: MediaTek, National Chiao Tung University, National Chung Cheng University ...read more
Bio: Yao-Wen Chang is an academic researcher from National Taiwan University. The author has contributed to research in topics: Routing (electronic design automation) & Equal-cost multi-path routing. The author has an hindex of 45, co-authored 382 publications receiving 8378 citations. Previous affiliations of Yao-Wen Chang include MediaTek & National Chiao Tung University.
Papers published on a yearly basis
01 Jun 2000
TL;DR: An efficient, flexible, and effective data structure, B-trees for non-slicing floorplans, based on ordered binary trees and the admissible placement presented in , and a B-tree based simulated annealing scheme for floorplan design.
Abstract: We present in this paper an efficient, flexible, and effective data structure, B*-trees for non-slicing floorplans. B*-trees are based on ordered binary trees and the admissible placement presented in . Inheriting from the nice properties of ordered binary trees, B*-trees are very easy for implementation and can perform the respective primitive tree, operations search, insertion, and deletion in only O(1), O(1), and O(n) times while existing representations for non-slicing floorplans need at least O(n) time for each of these operations, where n is the number of modules. The correspondence between an admissible placement and its induced B*-tree is 1-to-1 (i.e., no redundancy); further, the transformation between them takes only linear time. Unlike other representations for non-slicing floorplans that need to construct constraint graphs for cost evaluation, in particular, the evaluation can be performed on B*-trees and their corresponding placements directly and incrementally. We further show the flexibility of B*-trees by exploring how to handle rotated, pre-placed, soft, and rectilinear modules. Experimental results on MCNC benchmarks show that the B*-tree representation runs about 4.5 times faster, consumes about 60% less memory, and results in smaller silicon area than the O-tree one . We also develop a B*-tree based simulated annealing scheme for floorplan design; the scheme achieves near optimum area utilization even for rectilinear modules.
22 Jun 2001
TL;DR: The geometric relation among modules is transparent not only to the TCG representation but also to its operations, facilitating the convergence to a desired solution, and makes TCG an effective and flexible representation for handling the general floorplan/placement design problems with various constraints.
Abstract: In this paper, we propose a transitive closure graph-based representation for general floorplans, called TCG, and show its superior properties. TCG combines the advantages of popular representations such as sequence pair, BSG, and B*-tree. Like sequence pair and BSG, but unlike O-tree, B*-tree, and CBL, TCG is P-admissible. Like B*-tree, but unlike sequence pair, BSG, O-tree, and CBL, TCG does not need to construct additional constraint graphs for the cost evaluation during packing, implying faster runtime. Further, TCG supports incremental update during operations and keeps the information of boundary modules as well as the shapes and the relative positions of modules in the representation. More importantly, the geometric relation among modules is transparent not only to the TCG representation but also to its operations, facilitating the convergence to a desired solution. All these properties make TCG an effective and flexible representation for handling the general floorplan/placement design problems with various constraints. Experimental results show the promise of TCG.
TL;DR: This work proposes a high-quality analytical placement algorithm considering wirelength, preplaced blocks, and density based on the log-sum-exp wirelength model proposed by Naylor and the multilevel framework and uses the conjugate gradient method to find better macro positions.
Abstract: In addition to wirelength, modern placers need to consider various constraints such as preplaced blocks and density. We propose a high-quality analytical placement algorithm considering wirelength, preplaced blocks, and density based on the log-sum-exp wirelength model proposed by Naylor and the multilevel framework. To handle preplaced blocks, we use a two-stage smoothing technique, i.e., Gaussian smoothing followed by level smoothing, to facilitate block spreading during global placement (GP). The density is controlled by white-space reallocation using partitioning and cut-line shifting during GP and cell sliding during detailed placement. We further use the conjugate gradient method with dynamic step-size control to speed up the GP and macro shifting to find better macro positions. Experimental results show that our placer obtains very high-quality results.
11 Mar 2009
TL;DR: EDA/VLSI practitioners and researchers in need of fluency in an "adjacent" field will find this an invaluable reference to the basic EDA concepts, principles, data structures, algorithms, and architectures for the design, verification, and test of VLSI circuits.
Abstract: This book provides broad and comprehensive coverage of the entire EDA flow. EDA/VLSI practitioners and researchers in need of fluency in an "adjacent" field will find this an invaluable reference to the basic EDA concepts, principles, data structures, algorithms, and architectures for the design, verification, and test of VLSI circuits. Anyone who needs to learn the concepts, principles, data structures, algorithms, and architectures of the EDA flow will benefit from this book. Covers complete spectrum of the EDA flow, from ESL design modeling to logic/test synthesis, verification, physical design, and test - helps EDA newcomers to get "up-and-running" quickly Includes comprehensive coverage of EDA concepts, principles, data structures, algorithms, and architectures - helps all readers improve their VLSI design competence Contains latest advancements not yet available in other books, including Test compression, ESL design modeling, large-scale floorplanning, placement, routing, synthesis of clock and power/ground networks - helps readers to design/develop testable chips or products Includes industry best-practices wherever appropriate in most chapters - helps readers avoid costly mistakes Table of Contents Chapter 1: Introduction Chapter 2: Fundamentals of CMOS Design Chapter 3: Design for Testability Chapter 4: Fundamentals of Algorithms Chapter 5: Electronic System-Level Design and High-Level Synthesis Chapter 6: Logic Synthesis in a Nutshell Chapter 7: Test Synthesis Chapter 8: Logic and Circuit Simulation Chapter 9:?Functional Verification Chapter 10: Floorplanning Chapter 11: Placement Chapter 12: Global and Detailed Routing Chapter 13: Synthesis of Clock and Power/Ground Networks Chapter 14: Fault Simulation and Test Generation.
TL;DR: This article presents a class of universal switch modules that can accommodate up to 25% more routing instances, compared with the XC4000-type switch module of the same size and provides a theoretical insight into the important observation by Rose and Brown  that
F S=3 is often sufficient to provide high routability.
Abstract: A switch module M with W terminals on each side is said to be universal if every set of nets satisfying the dimensional constraint (i.e., the number of nets on each side of M is at most W) is simultaneously rout able through M. In this article, we present a class of universal switch modules. Each of our switch modules has 6Wswitches and switch-module flexibility three (i.e, Fs=3). We prove that no switch module with less than 6W switches can be universal. We also compare our switch modules with those used in the Xilinx XC4000 family FPGAs and the antisymmetric switch modules (with FS=3) suggested by Rose and Brown . Although these two kinds of switch modules also have FS=3 and 6W switches, we show that they are not universal. Based on combinatorial counting techniques, we show that each of our universal switch modules can accommodate up to 25% more routing instances, compared with the XC4000-type switch module of the same size. Experimental results demonstrate that our universal switch modules improve routability at the chip level. Finally, our work also provides a theoretical insight into the important observation by Rose and Brown  (based on extensive experiments) that FS=3 is often sufficient to provide high routability.
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
TL;DR: The hardware aspects of reconfigurable computing machines, from single chip architectures to multi-chip systems, including internal structures and external coupling are explored, and the software that targets these machines is focused on.
Abstract: Due to its potential to greatly accelerate a wide variety of applications, reconfigurable computing has become a subject of a great deal of research. Its key feature is the ability to perform computations in hardware to increase performance, while retaining much of the flexibility of a software solution. In this survey, we explore the hardware aspects of reconfigurable computing machines, from single chip architectures to multi-chip systems, including internal structures and external coupling. We also focus on the software that targets these machines, such as compilation tools that map high-level algorithms directly to the reconfigurable substrate. Finally, we consider the issues involved in run-time reconfigurable systems, which reuse the configurable hardware during program execution.
TL;DR: This tutorial paper collects together in one place the basic background material needed to do GP modeling, and shows how to recognize functions and problems compatible with GP, and how to approximate functions or data in a formcompatible with GP.
Abstract: A geometric program (GP) is a type of mathematical optimization problem characterized by objective and constraint functions that have a special form. Recently developed solution methods can solve even large-scale GPs extremely efficiently and reliably; at the same time a number of practical problems, particularly in circuit design, have been found to be equivalent to (or well approximated by) GPs. Putting these two together, we get effective solutions for the practical problems. The basic approach in GP modeling is to attempt to express a practical problem, such as an engineering analysis or design problem, in GP format. In the best case, this formulation is exact; when this is not possible, we settle for an approximate formulation. This tutorial paper collects together in one place the basic background material needed to do GP modeling. We start with the basic definitions and facts, and some methods used to transform problems into GP format. We show how to recognize functions and problems compatible with GP, and how to approximate functions or data in a form compatible with GP (when this is possible). We give some simple and representative examples, and also describe some common extensions of GP, along with methods for solving (or approximately solving) them.