Due to the fast-switching speed of the SiC devices, one of the many components that are most susceptible to EMI noise in a converter is the gate driver. Gate drivers are crucial to the normal operation of the power converters, however, those designed for medium voltage high power applications are prone to have false-triggering issues during normal operation. Studies have been shown to investigate the noise propagation mechanism on gate driver PCBs, particularly how the noise is induced on signal traces. Those mechanisms all consider the main circuit power stage is the root noise source. This paper reveals another factor that contributes to the noise on signal traces, particularly those routed as pads to reduce parasitic inductance. Excited by a voltage source vgs, the pad forms a patch antenna with the PCB ground plane beneath it. The issue is first identified by experiments with an actual SiC converter, then explained by a modified near field noise propagation model. Experimental results are shown to verify the model, and the interaction of noise caused by different noise sources (vgs and main circuit vds) is discussed. Finally, effective noise mitigation methods are proposed.
