Research On PCB Level Power Integrity In High-speed Communication System

Power integrity is the key problem of high-speed circuit design at present. It extends the concept of signal integrity. The essence of power integrity is the impact of power distribution system (PDS) for signal integrity. The research objects include power module, power plane, ground plane, bypass capacitor, encapsulation of high-speed chip and inside power distribution. It resolves synchronous switch noise (SSN), ground balance, edge and resonance effect problem completely. The elements of low-performance power module, synchronous switching of mass chips, and unreasonable PCB layout of the power/ground plane can bring the problem of power integrity. Good power integrity can ensure the value of fluctuate range for power plane is less than certain target value in frequency domain, but bad power integrity perhaps let other components act wrong, and bring about output un-correct value, or even make system not work.Following contents about PCB level PI of high-speed system are researched in this article:1) Introduce relevant definition of PI, and analyze the factors that cause PI problem, especially the synchronous switching noise, ground balance, and so on.2) Analyze the important effect of bypass capacitor for resolving power integrity.3) Establish the simulation models for switching power module, power/ground plane, and bypass capacitor.4) Through SPECCTRAQuset PI simulation tool of Cadence Ltd, these models are applied in PI analysis for MCM (Media Conversion Module) control module of media gateway A7XXX system. Parts of PDS are optimized.5) Initiate the PI simulation test environment with the dynamic electronic load, apply the environment to the PI test for MCM control module, and validate the influence of various bypass capacitors to PI design. Finally, the design principles and process of PI is also discussed.The design of high-speed communication system is a complex process. Now, how to prevent power integrity problems is an emphasis of system integrity design. Discussing and researching of PI problem will promote the ideas, concepts, process and methods of high-speed communication system design.