EMI Mechanisms, Parameters, and Measurements in High-Speed Systems: A Case Study of a Multi-Line Card Switch.

Dr. Caijun Zhao is currently serving as an Assistant Principal Expert at the 2012 Labs of Huawei Technologies Co., Ltd., focused on electromagnetics and protection. He received his Ph.D. degree in mechatronic engineering from Southeast University, Nanjing, China, in 2011. Dr. Zhao is engaged in the research and application of electromagnetics and protection technologies for communication systems, such as electromagnetic interference (EMI) of high-speed chips and systems, lightning and electrostatic protection, measurement of electromagnetic parameters of materials, and electromagnetic compatibility (EMC) testing.

Taking a switch with multiple line cards as an example, this report systematically expounds on the electromagnetic interference (EMI) mechanism of high-speed systems, the EMI parameters of high-speed components, and their measurement methods. The EMI of high-speed systems is produced by high-speed components, such as chips, connectors, and optical modules. While a chip radiates emission, it can also excite connectors’ radiation. The radiation of optical modules is divided into two parts according to where its radiation is from. The EMI of all high-speed components can be characterized in accordance with standard methods. Finally, the calculation and measurement results for some systems are given. The maximum discrepancy does not exceed 5 dB.