Signal Integrity Analysis And Optimization Design Of Transmission Lines And Vias In High-speed PCB

With the progress and development of communication technology,the signal transmission rate and clock frequency of electronic system equipment have been continuously improved.Simultaneously,the communication frequency has also been improved from the MHz field to the GHz field,and will also be developed to the THz field in the future.PCB is the physical bearing and concrete manifestation of electronic system.With the increase of signal frequency,the high-speed printed circuit boards used for signal transmission are increasingly becoming susceptible to signal integrity issues.Transmission lines and vias are the two most basic components of high-speed PCB,which are both indispensable in forming a transmission path.The via also exists as an impedance discontinuity point in the transmission path.Therefore,it is significant to study and analyze transmission lines and vias in high-speed PCB to solve the signal integrity problem in transmission path.In this thesis,the high-speed system theory is first analyzed,leading to signal integrity problems and transmission line theory.Furthermore,the lossless termination transmission line is analyzed and studied emphatically,exploring the transmission state of the transmission line,and analyzing the most suitable scenarios for the transmission line in different states.This thesis analyzes the role of S-parameters in the signal integrity research and the specific manifestations of signal integrity problems,studing the reflection and crosstalk that produce the widest range.Several kinds of termination technology to improve the reflection and crosstalk influence factors are studied,which obtains board-level signal integrity factors.Based on the research of conventional matching methods,the concept of segment transmission lines is derived and the genetic algorithm is proposed to be applied to the design of segment transmission lines,further analyzing the signal transmission performance of the transmission line designed in this thesis.Then the difference impedance and common-mode impedance of the signal transmitted in the difference line are studied,mainly focus on how to transform between the two factors and how to affect the signal integrity when transmitting in the difference line in terms of common-mode impedance.On the basis of theoretical analysis,the influence of the corner of the difference line on the signal integrity is studied and the compensation design of the corner is carried out through length compensation consideration.The parasitic capacitance and parasitic inductance of the via are analyzed,and the equivalent circuit model of the via is obtained.Based on the theory of scattering parameter network,the field-circuit combination analysis method is introduced.The influence characteristics of influence factors,such as aperture,pad and anti-pad,are obtained by via signal influence characteristics analysis.The transmission performance of the via is optimized from the perspective of reducing the backflow path,which was mainly realized by controlling the distance between the connecting line and the ground layer of via and the distance between the ground via and the signal via.And the transmission performance of via signal is optimized from non-functional pads and the number of ground vias.This thesis complete the corner analysis of the differential transmission line and the signal integrity analysis of the vias,studing the reflection and crosstalk,optimizing the design of the segment transmission line,designing the relevant physical model.The corresponding physical PCB experimental board is made and test the PCB experimental board and analyze the results,finally,put forward some suggestions for the production of high speed PCB.