Analysis of Voltage Regulator Module (VRM) Noise Coupling to High-Speed Signals with VRM Via Designs

The physical noise coupling mechanism between voltage regulator module (VRM) noise coupling to high-speed signal traces is analyzed and different noise reduction methods are analyzed for the first time. The rapid switching of field effect transistors (FETs) creates an unintentional coupling region around the VRM. As high-speed traces are often routed in the inner signal layers of printed circuit boards (PCBs) as striplines for signal integrity, the VRM switching noise is mainly coupled from noisy power vias to the victim traces routed around the VRM region. To analyze different coupling reduction methods in practical high-speed channels, a simplified PCB design based on a high-speed server platform is proposed. Case studies under various conditions verifies the most effective VRM noise coupling reduction method. Different design parameters that influence the VRM noise coupling are analyzed to provide a design guide for high-speed channel designers.