Performance comparison of Si and GaN transistors in a family of synchronous buck converters for LED lighting applications

Wide bandgap (WBG) semiconductors have emerged as an attractive option for silicon (Si) replacement in the recent years. Among the new materials, gallium nitride (GaN) has been considered as the most promising candidate. This paper presents a comparison between Si and GaN switching devices in a family of synchronous buck converters designed for LED lighting applications. Ten 48 V to 28.3 V at 22.6 W converters were designed under the same parameters at five different switching frequencies, ranging from 100 kHz to 1 MHz. Efficiency and temperatures were recorded in four different scenarios: with and without an external diode in parallel with the low-side switch and for two different dead time values, 25 ns and 50 ns. GaN based converters presented higher efficiency and lower operating temperatures in all the cases, with a maximum efficiency of 96.8% and a minimum of 94.5%. Besides, Si based converters exhibited a higher performance degradation as switching frequency and dead time increase.