Simulation based EMI Prediction for High Speed Differential Signals

Electromagnetic Interference (EMI) failure is a common occurrence in electronic devices. Failing to comply with FCC/CE requirements set by government agencies delays the product time to market. Besides following proper design guidelines of layout, grounding, shielding, filtering, etc., using simulation to predict EMI failures during early design stage will greatly save time and cost. In this paper, EMI from a practical product with multiple pairs of high speed differential signals are studied. The power spectrum density of both common mode and differential mode on those differential pairs are measured. By combining with noise source information and simulated far field transfer functions, the simulated EMI can be obtained. The simulation results are later compared with measured results to show the accuracy of simulations.