A Pre-Charge Tracking Technique in the 40 MHz High-Speed Switching 48-to-5 V GaN-Based DC-DC Buck Converter for Reducing Large Self-Commutation Loss and Achieving a High Efficiency of 95.4%

For automobile applications, a high-speed switching 48-to-5 V dc-dc buck converter is implemented in the 0.5- \mu \text{m} CMOS and 0.5- \mu \text{m} gallium nitride (GaN)-on-Si processes. This proposed converter includes a pre-charge tracking technique, a temperature-dependent controlled gate driver, and an adaptive relaxation gate drive control technique. The measurement results of this article show that the efficiency can be increased by about 10.3% and can ensure the driving current capacity of enhance GaN (E-GaN). The built-in local negative feedback loop improves the reliability and reduces R_{\mathrm{\scriptscriptstyle ON}} by 21% to reach the peak efficiency as high as 95.4%.