A knowledge-based approach to VLSI-design in an open CAD-environment

A knowledge-based approach is suggested to assist a designer in the increasingly complex task of generating VLSI-chips from abstract, high-level specifications of the system. The complexity of designing VLSI-circuits has reached a level where computer-based assistance has become indispensable. Not all of the design tasks allow for algorithmic solutions. AI technique can be used, in order to support the designer with computer-aided tools for tasks not suited for algorithmic approaches. The approach described in this paper is based upon the underlying characteristics of VLSI design processes in general, comprising all stages of the design. A universal model is presented, accompanied with a recording method for the acquisition of design knowledge - strategic and task-specific - in terms of the design actions involved and their effects on the design itself. This method is illustrated by a simple design example: the implementation of the logical EXOR-component. Finally suggestions are made for obtaining a universally usable architecture of a knowledge-based system for VLSI-design

Algorithm to layout (ATL) systems for VLSI design

PhD ThesisThe complexities involved in custom VLSI design together with the failure of CAD techniques to keep pace with advances in the fabrication technology have resulted in a design bottleneck. Powerful tools are required to exploit the processing potential offered by the densities now available. Describing a system in a high level algorithmic notation makes writing, understanding, modification, and verification of a design description easier. It also removes some of the emphasis on the physical issues of VLSI design, and focus attention on formulating a correct and well structured design. This thesis examines how current trends in CAD techniques might influence the evolution of advanced Algorithm To Layout (ATL) systems. The envisaged features of an example system are specified. Particular attention is given to the implementation of one its features COPTS (Compilation Of Occam Programs To Schematics). COPTS is capable of generating schematic diagrams from which an actual layout can be derived. It takes a description written in a subset of Occam and generates a high level schematic diagram depicting its realisation as a VLSI system. This diagram provides the designer with feedback on the relative placement and interconnection of the operators used in the source code. It also gives a visual representation of the parallelism defined in the Occam description. Such diagrams are a valuable aid in documenting the implementation of a design. Occam has also been selected as the input to the design system that COPTS is a feature of. The choice of Occam was made on the assumption that the most appropriate algorithmic notation for such a design system will be a suitable high level programming language. This is in contrast to current automated VLSI design systems, which typically use a hardware des~ription language for input. These special purpose languages currently concentrate on handling structural/behavioural information and have limited ability to express algorithms. Using a language such as Occam allows a designer to write a behavioural description which can be compiled and executed as a simulator, or prototype, of the system. The programmability introduced into the design process enables designers to concentrate on a design's underlying algorithm. The choice of this algorithm is the most crucial decision since it determines the performance and area of the silicon implementation. The thesis is divided into four sections, each of several chapters. The first section considers VLSI design complexity, compares the expert systems and silicon compilation approaches to tackling it, and examines its parallels with software complexity. The second section reviews the advantages of using a conventional programming language for VLSI system descriptions. A number of alternative high level programming languages are considered for application in VLSI design. The third section defines the overall ATL system COPTS is envisaged to be part of, and considers the schematic representation of Occam programs. The final section presents a summary of the overall project and suggestions for future work on realising the full ATL system

Silicon compilation

Silicon compilation is a term used for many different purposes. In this paper we define silicon compilation as a mapping from some higher level description into layout. We define the basic issues in structural and behavioral silicon compilation and some possible solutions to those issues. Finally, we define the concept of an intelligent silicon compiler in which the compiler evaluates the quality of the generated design and attempts to improve it if it is not satisfactory

Development of an architectural design tool for 3-D VLSI sensors

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 153-159).Three dimensional integration schemes for VLSI have the potential for enabling the development of new high-performance architectures for applications such as focal plane sensors. Due to the high costs involved in 3-D VLSI fabrication and the fabrication complexity of 3-D integration, analysis of the design and process tradeoffs for a particular application is essential. An architectural and topological design tool is presented that enables the high-level analysis and optimization of sensor architectures targeted to a variety of 3-D VLSI process options. This design tool is based on an inference chain evaluation framework, and allows for a high-level structural representation of a circuit architecture to be considered in conjunction with low-level process models. Approximation strategies for projecting circuit area and performance are incorporated into the inference chain relations.by Brian Tyrrell.S.M

Optimizing construction of scheduled data flow graph for on-line testability

The objective of this work is to develop a new methodology for behavioural synthesis using a flow of synthesis, better suited to the scheduling of independent calculations and non-concurrent online testing. The traditional behavioural synthesis process can be defined as the compilation of an algorithmic specification into an architecture composed of a data path and a controller. This stream of synthesis generally involves scheduling, resource allocation, generation of the data path and controller synthesis. Experiments showed that optimization started at the high level synthesis improves the performance of the result, yet the current tools do not offer synthesis optimizations that from the RTL level. This justifies the development of an optimization methodology which takes effect from the behavioural specification and accompanying the synthesis process in its various stages. In this paper we propose the use of algebraic properties (commutativity, associativity and distributivity) to transform readable mathematical formulas of algorithmic specifications into mathematical formulas evaluated efficiently. This will effectively reduce the execution time of scheduling calculations and increase the possibilities of testability

Survey of partitioning techniques in silicon compilation

In the silicon compilation design process, partitioning is usually the first problem to be investigated because partitioning algorithms form the backbone of many algorithms including: system synthesis, processor synthesis, floorplanning, and placement. In this survey, several partitioning techniques will be examined. In addition, this paper will review the partitioning algorithms used by synthesis systems at different design levels

Improving Coarsening Schemes for Hypergraph Partitioning by Exploiting Community Structure

We present an improved coarsening process for multilevel hypergraph partitioning that incorporates global information about the community structure. Community detection is performed via modularity maximization on a bipartite graph representation. The approach is made suitable for different classes of hypergraphs by defining weights for the graph edges that express structural properties of the hypergraph. We integrate our approach into a leading multilevel hypergraph partitioner with strong local search algorithms and perform extensive experiments on a large benchmark set of hypergraphs stemming from application areas such as VLSI design, SAT solving, and scientific computing. Our results indicate that respecting community structure during coarsening not only significantly improves the solutions found by the initial partitioning algorithm, but also consistently improves overall solution quality

A Cellular, Language Directed Computer Architecture

If a VLSI computer architecture is to influence the field of computing in some major way, it must have attractive properties in all important aspects affecting the design, production, and the use of the resulting computers. A computer architecture that is believed to have such properties is briefly discussed