Reducing radiated emissions from CPUs core power interconnect design

Radiated emissions associated with the second harmonic of the CPU core operating frequency often prove problematic throughout the design of computer systems. One of the primary radiating mechanisms for the second-harmonic emissions is high-frequency harmonic current injected from the CPU directly into the computer power distribution system (PDS). Prom the PDS, the current can couple to and radiate from other devices and/or radiate directly from the PCB. To mitigate the emissions from such current injection, as much current as possible must be kept from reaching the PCB. In this work, the design of the core-power interconnect for a CPU is modified to limit the level of high-frequency current injected into the PCB PDS. The design is driven by analyzing the parasitics associated with the PDS. A reduction of more than 12 dB in the radiated fields is achieved through a geometric redesign of the CPU socket interconnect.