Common mode EMI noise characterization and improvement for GaN switched-capacitor converter

The common mode (CM) noise issues in Gallium Nitride (GaN) based switched-capacitor circuit are investigated. The coupling mechanism due to the high rate of dv/dt in the voltage doubler converter is identified. A circuit model considering the GaN device, PCB stray inductance and parasitic capacitance, and passive components is derived to predict the CM noise generation and propagation. Based on the derived CM noise equivalent circuits, improvements to reduce the CM noise are proposed and verified by both computer simulation and experimental testing.