As data rates rise and the size and power margins shrink, signal integrity, power integrity, and EMC problems often originate from the same root causes: parasitic coupling, return-path discontinuities, and resonances across interconnects, packages, and PCBs. This presentation surveys practical modeling options—from rapid circuit parasitic extraction to full-wave 3D field simulation—to identify potential risk early, quantify worst-case behavior, and guide layout and mitigation decisions with confidence.