High-speed Digital Pcb Interconnect Signal Integrity Study

As the digital system's clock frequency is growing higher and the signal's switch time is getting shorter,and the impact of high-speed digital PCB interconnect design on the whole system's electrical characteristic is growing greater.In high-speed system,the interconnect among the high-speed signals will cause a series of signal integrity issues.Therefore,how to deal with the signal integrity issues caused by high-speed signal interconnects has become the key of a high-speed digital system design to success.This dissertation mainly studies Delay,Reflection,Crosstalk,discontinuity of microstrip, and other signal integrity issues caused by high-speed interconnects.This dissertation first analysed the reasons of reflection and crosstalk,and also shows the waveforms of reducing reflection by adding terminators and the waveforms of the crosstalk influenced by changing the parameters of transmission lines.And we got some measures to reduce crosstalk.Then, we focus on the differential line impedance control and anti-crosstalk ability of differential pairs.Through.the "field"&"Circuit" method,the difference interconnect transmission characteristic and the far-end crosstalk were simulated and analysed.Because the odd-mode and even-mode's propagation velocity existed difference,the difference microstrip structure in(?)uced extra noise.Finally,we do SI analysis and simulation to the discontinuity of the high speed interconnect such as:via,corner and slot.Through the analysis of S-parameters, we got these:a via transmission characteristic relates with the via,pad and anti-pad's diameter;The 45°outside bevelling structure has better transmission characteristic.The mismatch of differential comer length introduces difference noise,which relates with the rise time;The slot in ground plane causes the return route inductance to increase,introduces discontinuity,it should be avoided in the design.In short,we could draw some conclusions which can reduce SI issues through simulation and analysis.According to these,we can make layout,routing rules to restrain PCB design,so the design can achieve good performance,shorten the development cycle of hardware.And it also proved the importance to make SI analysis to high-speed interconnect.