On switch factor based analysis of coupled RC interconnects

We revisit a basic element of modern signal integrity analysis, the modeling of worst-case coupling capacitance effects within a switch factor (SF) based methodology. We show that the exact SF is a function of the ratio of slew times of both aggressor and victim interconnect voltages. Our main result is that 2Cc (or, SF = 2), where Cc is the static coupling capacitance, is not a correct upper bound when calculating interconnect delay in presence of crosstalk: we show that for signals modeled as finite ramps the worst case is SF = 3. This has implications for almost all signal integrity methodologies, e.g., window-based approaches that iteratively determine worst-case coupling effects. We have tested our result in a worstcase delay analysis methodology by transforming the coupled RC network to an RC network where each coupling capacitance C is replaced by a capacitance 3C to ground. SPICE simulation confirms the accuracy of worst-case delay estimates produced using SF = 3. Delay with S...

• Type: Conference
• Year: 2000
• Where: DAC
• Authors: Andrew B. Kahng, Sudhakar Muddu, Egino Sarto
• Keywords: DAC 2000, Design Automation, Static Coupling Capacitance, Worst-case Coupling Capacitance, Worst-case Coupling Effects