Signal Integrity Analysis Of Transmission Lines On High-speed PCB

Printed circuit board(PCB) as a carrier of high-speed signal transmission, plays an extremely important role in areas such as aviation, communication and computer. With the progress of information technology, PCB itself faces severe challenges. On one hand, with the decrease of PCB volume and the increase of integration, transmission lines are becoming more and more complicated; on the other hand, the rising edge is becoming shorter and shorter. The above two aspects would result in some signal integrity(SI) problems, such as reflection, crosstalk and radiation. These problems could make the digital circuit system trigger mistakenly, output signal waveform distorted and instable, etc., which will largely influence the performance of products. Therefore, signal integrity analysis of transmission lines must be considered at the beginning of the design, so that potential problems could be solved, and PCB performance is consequently improved, as well as product economic benefits.Combined with the actual situation closely, this thesis conducts signal integrity analysis for the typical wiring form of the high-speed PCB of single-end line and differential. Since the scattering parameters can be used to evaluate the signal integrity, they are adopted as the metric in this paper. Firstly, we analyze the scattering parameters of bending coupled microstrip lines and two differential lines. Specifically, piecewise analysis method is used for the bending coupled microstrip lines, which can be divided into the parallel and bending parts. For the parallel part, the odd-even mode method is adopted. For the bending part, the ? circuit model is used. To calculate the crosstalk between differential lines, multi-conductor transmission line theory is applied. The link parameter matrix, which describes the relationship between the input and output voltage and current, is used and then converted into scattering matrix. Finally, the simulation results are presented, which are in agreement with the theoretical analysis.Then, we conduct a series of signal integrity simulations for 16-layer PCB. Specifically, we check the signal integrity of the total PCB, and obtain the crosstalk network. Then, we conduct the crosstalk and electro-magnetic interference(EMI) measurement for such networks, and optimize the transmission lines with higher crosstalk than the values given in the international standard, so that some requirements could be satisfied. In addition, analysis of scattering parameters and eye diagram is conducted with typical transmission lines.To sum up, this thesis analyzed the signal integrity problems of interconnects based on scattering parameters. Moreover, we conducted signal integrity simulation of interconnects on high-speed PCB. The proposed simulation process of PCB signal integrity in this thesis can provide references for other PCB post-simulation.