A Closed-Loop EMI Regulated GaN Power Converter With In Situ EMI Sensing and Global Excess-Spectrum Modulation

As electromagnetic interference (EMI) standards evolve from the rules-based approach to the risk-based alternate, online EMI assessment and control become critical for lifetime risk management. With such a trend, this article presents an online closed-loop EMI regulation for gallium-nitride (GaN) power converter. Specifically, a wide-bandwidth in situ EMI sensor is integrated to characterize the noise through autocovariance-based spectrum analysis. A stepwise random space sampling (SRSS) significantly compresses the sensing time without sacrificing the accuracy for real-time EMI spectral characterization. Based on the online measured noise, a global excess-spectrum modulator is devised to adaptively track, and hence, continuously regulate the maximum excess noise. A prototype chip was fabricated in a 180-nm BCD process, commanding two enhancement-mode GaN power switches at a nominal frequency of 2.8 MHz. The measurement results show that the integrated in situ EMI sensor can capture the EMI spectra with a 500-MHz sampling bandwidth and 1-mV sensing accuracy while reducing the sensing time by over 25 times. Compared to the commercial spectrum analyzer, it demonstrates a maximum discrepancy of 3 dB. The embedded global excess-spectrum modulator accomplishes a 9-kHz-resolution EMI regulation, dynamically optimizing the EMI control.