高速PCB过孔设计研究进展

传输线连续性问题已成为当今高速数字电路设计的重点,尤其是多层PCB中大量使用的过孔结构。随频率的增加和上升时间的缩短,过孔阻抗不连续以及寄生电容、电感会引起信号反射和衰减,并进一步导致信号完整性（SI）问题。综述了高速电路中单端和差分过孔的孔径、孔长度等设计参数对阻抗连续性和S参数的影响,并介绍了三种提高过孔信号传输质量的方法,包括避免多余短柱、非穿导技术以及为过孔信号提供返回路径。本文能够为高速数字电路设计者进行过孔信号完整性判定提供参考。

Advances in via holes design of high-speed PCB

In all modem high-speed digital board designs,every slightest discontinuity on the board has to be considered carefully,especially via holes,which are abundantly used in multilayer PCB.As frequency increases and signal rise time reduces,via holes cause impedance discontinuities,parasite capacity and inductance which result in signal reflection and attenuation,and hence deterioration of signal integrity（SI）.This paper provides overview of recent advances in single-ended and differential via holes design for high-speed digital board.And the impacts of various design parameters on SI were also reviewed.Furthermore,the methods to improve SI for via holes were introduced,including back drilling technology,blind and buried via technology,and providing return current path.This paper allows high-speed digital designers to have a more in-depth assessment of via holes design and their effects on SI performance.