Accurate Prediction and Mitigation of EMI from High-Speed Noise Sources using Full Wave Solver

Unintended Electromagnetic interference (EMI) is a common occurrence in all consumer electronics, which can often fail compliance margins of FCC and/or CE, when best practices of grounding, shielding and overall system integration are not followed. The measurement of EMI for regulatory compliance has been studied extensively and there are standard test labs which certifies for EMI. However, predicting the EMI radiation from a consumer electronic device through simulation is very challenging due to the complexities involved in modeling the device and noise source. This paper introduces a workflow for simulating one case of EMI radiation from a 208 MHz single-ended I/O clock generated from the System-on-Chip (SoC) in an electronic device. Through a full wave 3D solver, the radiated far field transfer function of the clock is obtained. Additionally, the spectral content of clock is measured in both time and frequency domain. Then the clock spectrum is combined with transfer function to predict EMI radiation envelope. The simulated results are then compared with the measured results from an FCC compliant laboratory. Based on the simulated and measured results, mitigation techniques are proposed to reduce the EMI to acceptable levels.