More and more high - switch - rate and high - pin - density devices have been applied to the digital system along with the fast development of manufacture technics of integrate circuit ( up to 65nm ) , while the supply voltage of electronic system shows itself a fallen trend ( from 5v to 1 . 2v ) , signal integrity ( si ) , power integrity ( pi ) and electromagnetic compatibility ( emc ) problems have become increasingly serious 具体体现到高速pcb板级设计上,则为信号完整性( signalintegrity ,简称si ) 、电源完整性( powerintegrity ,简称pi )和电磁兼容性( electromagneticcompatibility ,简称emc )问题的影响已经达到了不可忽略的地步,经常会出现逻辑功能正确的数字系统不能在物理结构上实现。