High-Performance Electronic Design: Predicting Electromagnetic Interference
Ansys
This white paper from ANSYS presents a simulation methodology for predicting electromagnetic interference (EMI) during the electronic design process, rather than discovering compliance failures late in development during regulatory testing. The paper argues that EMI is not a problem in itself but a symptom of underlying signal integrity and power distribution issues. The core methodology involves four steps: capturing the system geometry, extracting an electromagnetic model over the frequency range of interest using an EM field solver, linking that model into a time-domain circuit solver to simulate real-time system response with transient signals, and then pushing those time-domain results back into the EM model to calculate the true EMI signature. This closed-loop approach spans three domains — time, frequency, and space — and requires both EM field solvers and circuit solvers working together. ANSYS tools such as SIwave (optimized for PCB-level analysis), HFSS (for full 3D structures including enclosures and anechoic chambers), and DesignerSI (the hybrid circuit solver) enable this workflow. Design data from EDA and MCAD environments is imported directly, and features like dynamic links and push excitations automate the data exchange between frequency and time domains. A case study from Inovax demonstrates the methodology applied to a rectifier, where simulated results correlated well with physical measurements, identified an offending trace near 60 MHz, and confirmed that adding a mechanical enclosure resolved remaining radiated emissions concerns.