Issue link: https://resources.pcb.cadence.com/i/1541046
34. Specifying Controlled Impedance and Reference Plane Requirements High-speed signals (such as clocks, data buses, differential pairs, and RF lines) require precise impedance control to maintain signal integrity, minimize reflections, and comply with interface specifications (USB, HDMI, PCIe, DDR, etc.). Controlled impedance is determined by trace geometry, stackup, and the proximity of reference planes. Failing to specify or verify impedance can lead to eye closure, bit errors, EMC failures, or non- compliance with standards. When And Where To Apply Define and document impedance requirements during stackup planning and before starting routing for all controlled impedance nets, especially high-speed, RF, and differential pairs. Revisit before signoff to ensure compliance after any stackup or design change. Use OrCAD X for impedance analysis of all nets in the design