PCB设计中阻抗匹配的信号改善方法

Signal improvement method for impedance matching in PCB design

为了研究阻抗匹配对传输线上高速信号质量的改善效果,结合传输线理论分析了高速信号在传输线上传导时发生反射的原因以及避免信号发生反射的阻抗匹配方法,介绍了5种阻抗匹配方式的特点。采用Hyper lynx仿真软件分析了控制板卡印制电路板(PCB)设计中现场可编程门阵列(FPGA)到数字信号处理器(DSP)之间一条传输线上的信号质量,对比分析了有无串联匹配电阻、源端串联匹配电阻、中端串联匹配电阻和末端串联匹配电阻的信号质量。结果得出,传输高速信号的电路系统应该进行阻抗匹配,对于串联匹配电阻,在PCB布局设计中应尽量将匹配电阻靠近信号源端放置。

In order to study the effect of impedance matching on improving the quality of high-speed signals on transmission lines,the causes of reflection of high-speed signals when transmitting on transmission lines and the impedance matching methods to avoid reflection of signals are analyzed based on the transmission line theory,and the characteristics of five impedance matching methods are introduced.Hyper lynx simulation software is used to analyze the signal quality of a transmission line between field programmable gate array(FPGA)and digital signal processor(DSP)in a certain control board printed circuit board(PCB)design.The signal quality with or without series matching resistance,with source series matching resistance,middle series matching resistance,and end series matching resistance are compared and analyzed.The results show that impedance matching should be performed on circuit systems that transmit high-speed signals.For series matching resistors,the PCB layout design,in the matching resistors should be placed as close to the signal source as possible.