Application of Frequency-Domain Noise-Source Model to Simulation of Time-Synchronized Near-Magnetic-Field Distribution above a Power Circuit

The high-electromagnetic-interference (EMI)-noise area in a power circuit should be clarified when designing a low-EMI-noise power converter. For example, shielding of the power circuit prevents the EMI noise propagation to other circuits via near field couplings. It is important to know the high-EMI-noise area which should be shielded. The EMI noise distribution can be visualized by measuring the near-magnetic-field distribution above the power circuit. However, we cannot measure the near-magnetic-field distribution if there is not enough space for scanning a magnetic field probe between the power circuit and other circuits. Therefore, we propose to adopt a three-dimensional electromagnetic simulation for acquiring the near-magnetic-field distribution above a power circuit. In this paper, we study the validity of the frequency-domain noise-source model for the simulation of the near-magnetic field distribution. We evaluate the near-magnetic-field distribution maps for turn-on and turn-off of the transistor, respectively. The high-EMI-noise area differs depending on frequencies. The high-EMI-noise area for turn-on is different from that for turn-off. We have clarified that each high-EMI-noise area can be predicted by the simulation.