Investigation of crosstalk for micro-strip lines over non-ideal reference plane by using FDTD

In high-speed circuit design, the reference plane under signal traces should remain continuous or the number of signal traces traversing the discontinuous reference plane can not be more than one whenever possible. However, in practical multilayer high-speed PCB routing, the signal traces often have to traverse over via anti-pads or even a ground gap. Thus a non-ideal reference plane is formed and it leads to serious signal integrity problems. This paper introduces the FDTD method for analysis of signal integrity of the high-speed circuit. And the full-wave analysis of crosstalk for micro-strip lines over non-ideal reference plane is carried out by using FDTD. The crosstalk coupling mechanism is discussed. Furthermore, the numerical results demonstrate the measures for inhibiting crosstalk are effective.