Waveform degradation in VLSI interconnections

The interconnections between circuits on VLSI chips have a major effect on overall circuit performance. In the past, lumped circuit approximations have been used with numerical integration to analyze distributed interconnection effects on circuit switching speed. Such approximations are useful for specific cases, but they provide little general insight. Here, the exact time-domain response for a ramp function driving the general resistive-capacitive transmission line is derived. The resulting equation is analyzed to show the effect of the lines electrical parameters on its transient response. Equation time constants, which include fringing and coupling capacitance, are derived. Transient responses for specific metal, polysilicide, and polysilicon lines are plotted and analyzed.>