Signal integrity loss in bus lines due to open shielding defects

The interconnect structures in high speed circuits play an important role in present CMOS technologies. Inductance and capacitance coupling effects (crosstalk) may cause a significant loss in signal integrity in high performance systems. One way to reduce these effects is to place a signal line between two grounded lines (shield). In this paper we study the influence of defective grounding of shielding lines. We focus on resistive open defects due to manufacturing problems or broken vias. Faulty shields may cause undershoots or ringings in signals traveling in long interconnect lines. Simple expressions for undershoots and overshoots have been derived using dominant poles and employed to determine the zones of signal integrity violation for different lengths of interconnect lines. The results show the impact of defective grounded shields.