EMI-Regulated GaN-Based Switching Power Converter With Markov Continuous Random Spread-Spectrum Modulation and One-Cycle ON-Time Rebalancing

Abstract

To meet stringent electromagnetic interference (EMI) requirements in modern integrated systems, this article presents a gallium nitride (GaN)-based switching power converter operating at 8.3 MHz. It employs a Markov continuous ran- dom spread-spectrum modulation (RSSM) technique to spread EMI spectra almost uniformly, and thus attenuate EMI level effectively. On the other hand, a one-cycle ON-time rebalancing scheme is designed to stabilize the duty-ratio of the converter even if the switching frequency changes randomly, suppressing the output voltage jittering without influencing the EMI reduction by RSSM. A prototype was designed and fabricated using a 0.18-µm HV CMOS process. With ±10% modulation range of a nominal switching frequency of 8.3 MHz, peak EMI is reduced from 66 to 35 dB µV at the fundamental frequency and from 62 to 27 dBµV at the third-order harmonic. In the meantime, the RSSM-induced output voltage jittering is suppressed from 240 to below 10 mV . The converter achieves above 60% efficiency over 96.6% of 7.5-W full power range, with a peak efficiency of 86.8% at 6.25 W.