Application Of Signal Integrity In PCB Design

Few years ago, circuit design engineer did not have to consider problems of signal integrity. However, nowadays designer can not neglect such problems. Smaller and smaller circuit area, higher and higher circuit density, high required layout and big size components, let engineer difficultly work. If design circuit based on traditional design technique, it is hardly to design a product with high reliability. All of these force us to introduce signal integrity analysis technique in to our design. At the beginning analyze signal rules, and then we load the result into layout tools to finish the product. By this process we can assure the signal quality and work efficiently.In my thesis, we state the importance and conception of SI (Signal Integrity). Next we introduce fundamentals of PCB, especially we discuss the multiple layers board. Make classifications of transmission line, analyzing 5 aspects of problems we meet in signal integrity. Dissert the theories and related formulas.Next chapter, we analyze all the aspects of signal integrity. Give each problem a practical solution to split design, ground line, reflections control, crosstalk control, SSN/SSO control, EMI control, and PCB size and components layout.Finally, we use the theories and instructions in a real project, to design a smart electrical meter.Schematic diagram is the basis of PCB design. So we have to design schematic diagram firstly. Reference to functionalities, we divide meter circuit in to measurement circuit, control circuit and peripheral circuit three parts. We analyze digital signals and analog signals in each part. We give impedance matching, decoupling capacitors, power filter capacitors signal integrity solutions. Next we give details descriptions to chips and design methods used in ten modules. Use Protel DXP to design each module's schematic diagrams.In the last chapter, based on previous designs, we calculate the parameters of board layers and transmission line impedance in our design. Use Polaris S6000 to verify the signal integrity of transmission lines. According to the theories of mix-signal design, we use Protel DXP design board size, drills layout, components layout. Mainly focus on the digital and analog district split design. Especially the power line split, digital ground and analog ground split and bridge connection design. Have practical value to product engineering.