The Case of the Unresponsive PDN

摘要

MUCH OF THE talk in the simulation world lately is focused on power. Even SI experts are starting to see how power has a material impact on their high-speed data transfer success. With power on the forefront, what effect will that have on the additional design demands of low-frequency supplies? Why should you consider power throughout your design process? Signal integrity, at its basic core, studies and describes the effects physical structures have on a signal, as it is transmitted from a source (transmitter) to a destination (receiver), but makes no mention of where the energy for the signal originates, or where it goes once received. Although a bit of oversimplification, the transmitting IC pulls energy from its power supply, bundles it as a bitstream and transmits data to a receiving IC, where the energy is dumped onto the ground and eventually returns to the power supply, ready to repeat. Admittedly, today's high-speed signals are largely differential and draw from multiple power rails, so we aren't describing the exact current flow. What we are describing is the notion that reliable data transmission involves both a clean path from driver to receiver in addition to a well-designed plan to deliver and return needed power.