Study On Construction Of Component Library And Auto Routing In Circuit CAD

The Computer-Added Design (CAD) in electron & circuit is a new technology having been developed for 50 years since the 50s last century. Its appearance brings new life to conventional circuit design. This paper describes the general developmental situation of CAD for electric circuit and the primary structure of circuit CAD software. Furthermore, this paper makes a preliminary study on circuit CAD software.Firstly, construct electronic component library. Electronic component library is an important part of circuit CAD. This paper analyses a great deal of figures of electronic component in circuit schematic, draws out some elementary figures that comprised these component figures, designs their storage structures, and building component files and afterwards units these files into one component figures database. When displaying these elementary figures on computer screen, we bring forward a new method to display a segment of cubic B-spline curve which is smoother than that by usual method.Secondly, generate netlist. Netlist is the interface between circuit schematic and printed circuit board (PCB), and also a precondition of electronic design automatic (EDA). The paper analyses the relationship between every component, with particular attention being paid to the topological relationship between several types of wire, unifies these types of wire into one and designs its storage structure. Through a series of operations on wires such as splitting, attaching, merging, etc, we convert wires got from circuit schematic into unit wires. At length, we export the netlist in virtue of data structure tree. During above processes, we put forward other concepts such empty wire, full wire, virtual wire.Finally, this dissertation presents the history and current status of auto routing algorithm in PCB, and gives the primary idea of line-search routing algorithm based on figure.All programs referred in this paper have been realized in computer by using C++ language, and the expectant objective is attained.