Comparative Study of Lateral and Trench Power MOSFETs in Multi-MHz Buck Converter Applications

This paper presents a comparative study of lateral and trench power MOSFETs in hard switching synchronous buck converters operating in the multi-MHz frequency range based on a mixed-mode device/circuit modeling approach. Detailed power loss analysis is performed for the control and synchronous MOSFETs. It is observed that the inherently low gate charge QG of lateral MOSFETs offers significant reduction in gate drive losses, which become increasingly important in the multi-MHz frequency range and especially light load conditions. Furthermore, the power loss due to the reverse recovery of the SyncFET body diode becomes a major limiting factor in the MHz frequency range for both trench and lateral MOSFETs. This factor will eventually determine the maximum practical switching frequency of the buck converter.