Fundamentals of Power Integrity for Computer Platforms and Systems

Chapter 6System Considerations for Power Integrity

Besides the power source, load, and distribution elements, there are a number of platform-level elements that need to be considered (electrically) when analyzing power at the system level. As observed in the preceding chapters, not only does one need to consider the PDN but also how the PDN responds to the dynamic behavior of the load and source and the efficacy of the power that is delivered to the load. In the time-domain analysis, of Chapter 5, it was clear that load perturbations indicate how good (or bad) the power distribution path and full system power delivery is. This was done by analyzing the different voltage droops due to different loads. However, only the simple case was examined where the voltage setpoint was kept static. What if this setpoint were allowed to move in response to load changes? This is one of the areas that is explored in this chapter to broaden the scope of the power integrity engineer's learning. Also the effects of noise in the PDN will be introduced, since this adds to what is termed the guardband of the power system. The different noise sources will be broken down and examined in terms of how they affect the quality of the power distribution network at the load. Also considered will be the different techniques used to squelch some of the noise sources. We examine electromagnetic interference as it pertains to power integrity, different EMI sources, and emissions due to EMI. Finally, some basic ...