Definition

High-speed design refers to signals where transmission line effects become significant - typically rise times under 1ns or frequencies above 100MHz. At these speeds, trace geometry affects impedance, vias add inductance, and return paths matter. Key concerns: controlled impedance, length matching for differential pairs, via stub resonance, crosstalk, and power delivery network impedance. Materials matter too - lower Dk means faster propagation, lower Df means less loss. PCIe, DDR4/5, USB3, and Ethernet all require high-speed design practices. Simulation (IBIS, S-parameters) validates designs before fabrication.