高速高密度PCB信号完整性与电源完整性研究

发布时间：2018-04-19 16:23

本文选题：高速 + 高密度　；参考：《西南交通大学》2015年硕士论文

【摘要】：高速高密度电路板是现阶段电子系统发展的必然趋势,在强辐射源与高功率微波领域中,由高速和高密度环境引起的信号完整性和电源完整性问题不容忽视。本文针对某基于FPGA电机控制系统的高速高密度电路板,分析其板级信号完整性和电源完整性问题,以及连接器的信号完整性问题。本文对高速高密度PCB信号完整性和电源完整性进行研究。首先,明确高速、高密度、信号完整性和电源完整性的基本概念,调研国内外信号完整性和电源完整性的研究现状,分析其产生原因和表现形式,如串扰、反射和同步开关噪声等,并对这些表现形式进行深入研究,分析其产生的根本原因、影响因素和减小不良影响的方法。其次,对该PCB进行层叠结构的分析和设计,通过传输线类型的分析和特性阻抗的计算得到不同信号层传输线的线宽及厚度,预估计串扰影响,根据3W原则、3H原则和布线需求得到线距,完成布局和布线的设计。利用FPGA的可编程性建立高低速混合模型,根据电机控制信号线和SDRAM信号线时序要求的不同,选择恰当的IBIS驱动器模型,建立时域电路模型进行时域仿真,得到传输线的传输特性,并选择多跟相邻传输线进行串扰分析。然后,对FPGA负载进行最优化设计,通过仿真计算Z-f曲线和电源纹波,分析两种不同负载方案的优劣并确定负载方案。根据Z-f曲线设计去耦网络,添加去耦电容,降低目标阻抗以减小电源纹波。在完成优化负载和去耦网络设计的基础上,从理论分析和仿真验证的角度,分析过孔结构对电源分配网络性能的影响,得到过孔内径、焊盘和反焊盘的最佳设计尺寸,指出除了传统的优化负载设计和添加去耦电容的方式之外,还可以通过修改过孔结构优化电源纹波,实现电源纹波的最优化设计。对电机控制板与电机之间某型号连接器进行仿真分析。运用仿真软件对其3D建模,运用场路结合的分析方法,计算其S参数,提取并导入时域仿真软件,得到连接器的传输特性。取相邻的多对引脚进行分析,仿真计算其串扰影响。对比传统的阻抗匹配方式进行优化,指出阻抗匹配法的局限性；采用从高速到低速转换的方法,完成连接器传输特性的优化,使连接器在PCB中得以良好的运用。根据前文仿真内容完成PCB的设计并加工,得到实物。用示波器对加工完成的PCB进行测试分析,得到单根传输线的传输特性,对比仿真结果,验证PCB传输线具有良好的传输特性。测试电容引脚两端电源纹波,验证PCB的电源纹波满足应用需求,具有较好的电源完整性。
[Abstract]:High speed and high density circuit board is the inevitable trend of electronic system development at present. In the field of strong emitter and high power microwave, the signal integrity and power integrity caused by high speed and high density environment can not be ignored.In this paper, the problems of board level signal integrity, power supply integrity and connector signal integrity are analyzed for a high speed and high density circuit board based on FPGA motor control system.In this paper, the signal integrity and power integrity of high speed and high density PCB are studied.First of all, make clear the basic concepts of high speed, high density, signal integrity and power integrity, investigate the research status of signal integrity and power integrity at home and abroad, analyze their causes and manifestations, such as crosstalk,The reflection and synchronous switching noise and so on are studied in depth to analyze the root causes of these manifestations, the influencing factors and the methods to reduce the adverse effects.Secondly, the stack structure of the PCB is analyzed and designed. Through the analysis of transmission line type and the calculation of characteristic impedance, the line width and thickness of different signal layer transmission lines are obtained, and the influence of crosstalk is pre-estimated.According to the 3W principle and the routing requirement, the distance between the lines is obtained, and the layout and routing design is completed.The high and low speed hybrid model is established by using the programmability of FPGA. According to the different timing requirements of the motor control signal line and the SDRAM signal line, the appropriate IBIS driver model is selected, and the time domain circuit model is established to carry out the time domain simulation.The transmission characteristics of transmission lines are obtained, and crosstalk analysis of multiple adjacent transmission lines is carried out.Then, the optimal design of FPGA load is carried out. The Z-f curve and the power ripple are simulated and calculated. The advantages and disadvantages of the two different load schemes are analyzed and the load schemes are determined.According to Z-f curve, decoupling network is designed, decoupling capacitance is added, and target impedance is reduced to reduce the ripple of power supply.On the basis of the optimization of load and decoupling network design, from the angle of theoretical analysis and simulation verification, this paper analyzes the influence of the perforated structure on the performance of the power distribution network, and obtains the optimum design size of the overhole inner diameter, the pad and the reverse pad.It is pointed out that in addition to the traditional ways of optimizing load design and adding decoupling capacitors, the optimal design of power ripple can also be realized by modifying the structure of perforated power supply.A certain type of connector between motor control board and motor is simulated and analyzed.The 3D model was modeled by simulation software, and the S parameters were calculated by the method of field circuit analysis. The time domain simulation software was extracted and imported, and the transmission characteristics of the connector were obtained.Several pairs of adjacent pins are analyzed and the crosstalk effect is simulated.Compared with the traditional impedance matching method, the limitation of the impedance matching method is pointed out, and the transmission characteristics of the connector are optimized by using the method of high speed to low speed conversion, so that the connector can be well used in PCB.According to the above simulation content, the design and processing of PCB are completed, and the object is obtained.The transmission characteristics of a single transmission line are obtained by testing and analyzing the finished PCB by oscilloscope. The simulation results show that the PCB transmission line has good transmission characteristics.The power ripple at both ends of the capacitor pin is tested to verify that the power ripple of PCB meets the requirement of application and has good power integrity.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN41

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