Design Of High-Speed Printed Circuit Board And The DDR2 Simulation

With the development of micro-electronics technology and computer technology, the problems of power integrity, signal integrity and electromagnetic compatibility become more and more prominent. Application of signal integrity analysis is the only way to solve high-speed system design. By dint of SpecctraQuest, which is a powerful simulation software, it is a simple analytical method to make use of IBIS model to analyze signal integrity on high-speed signal lines before layout and routing. This method can find out signal integrity problem and make optimization design on interrelated problem of signal integrity.In this paper, the method of high-speed printed circuit board design, based on signal integrity and electromagnetic compatibility, is explained in detail. The design of a mainboard, applied to notebook PC, meeting the requirements of signal integrity and electromagnetic compatibility, is finished. The material used to the mainboard is FR-4 (fiber glass/epoxy resin), the stackup structure with eight layers is applied. The theory of high-speed digital system design are interpreted, the analysis of signal integrity and electromagnetic compatibility is the key. And the design of high-speed printed circuit board, meeting the requirements, is expounded. Then the design is finished finally.In this design, referring to design requirements, provided by IC manufacturer and determined by simulations, the devices and process condition are selected. Besides, the cost, layout, power and routing are determined. Simulation of DDR2, an important part of the mainboard, is carried on specially. In simulations, the IBIS (Input/Output Buffer Information Specification) models are used. The reflection, crosstalk and digital timing are analyzed. It gives effective methods to reduce reflection and crosstalk, length matching of transmission lines, meeting the requirements of digital timing, is also presented. In the crowed area under the chip, special rules are applied. Finally, the design rules are determined.The design indicates it is necessary to adopt emulational design based on signal integrity and electromagnetic compatibility in high-speed PCB design. It can reduce the risk of failure, repeated design, design cost and period. The mainboard, meeting the design requirements, has been manufactured.