Power Loss Reduction of Low-Voltage Power MOSFET by Combination of Assist Gate Structure and Gate Control Technology

A new structure with the optimum gate control is proposed for low power loss operation of low-voltage power MOSFETs. Although the application system requires continuing the on-resistance R on A reduction for more power efficiency improvement, R on A trend is facing the theoretical limit even with the FP technology. Assist Gate (AG) structure was proposed to improve the R on A and turn-off loss E off tradeoff, because the channel and drift resistances can be reduced with avoiding the C gd increase by dual gate control. Dual gate control with synchronous rectify (SR) of AG-MOSFET also improves turn-on switching performance. This paper shows the AG-MOSFET with optimum gate control achieves 27% lower turn-on loss E on and 42% lower surge current compared with no SR operation. A case study of the half-bridge application also shows 17% to 46% of total power loss reduction.