| People's increasing demands for high bandwidth, used to be a high transmitting channel, push the continuous enhancement of the speed of microprocessors and buses. There are, now, in markets, processors of several hundreds of million hertz to several giga hertz with their buses in such a high work frequency from 133MHz to 800MHz everywhere. Furthermore, even higher speed components will emerge in the near future, to satisfy people's requirement of the real time transfer of data, voice and image. However, now, for this, hardware electronic designer are facing a new and critical problem----SI.However, now, as the digital system's clock frequency is growing higher and the edge rates are getting faster, the printed circuit board (PCB) system becomes a high performance platform which is not simply supporting the electronic device before. In today's high speed circuit applications, it is a common design problem to observe interconnect problems, say, reflection, crosstalk, delay, etc. These effects may result in significant distortion in pulses which propagate even a short distance. In addition, elector-magnetic interference will become prominent along with the increase of edge rate and frequency. Thus, Signal integrity and electro-magnetic compatibility during signal propagation turn into the two main problems of modern circuit integration. These problems bring greater challenges to the hardware system designers; many correct designs from the logic point of view would tend to fail if not well dealt with during real PCB design. Experts have predicted that the cost of logic design will decrease greatly in the future hardware design, whereas the cost related to high speed design will account for eighty percent or more of the total cost. High speed interconnect design has become the dominant factor of system design.Qualified signal integrity must be considered during the whole design process while the traditional method is depended on personal experience which can't meet the high performance and high density of PCB design. An analysis and simulation method based on the IBIS (Input/Output Buffer Informational Specification) can solute the potential SI problems in the design level and be valid to achieve a successful design. Based on the SI principle, the thesis analyses some SI problems in a PCB system such as Reflection, Crosstalk Delay and SSN, and also discusses the solutions of relative problems. Then it takes a visual decoding hardware system, to analyse and design the system using high-speed PCB's SI design process. Under the Cadence PSD 15.1 kit and Hyperlynx, the design simulate and resolve the SI problems of key net such as routing topology, Crosstalk and customize the routing rules according to the pre-routing simulation's results. After routing the whole traces, it also verifies the key routing nets by simulation. The SI design shows right effect and shortens the PCB designing cycle. The simulation results further prove the importance of SI simulation. |
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