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 RonA reduction for more power efficiency improvement, RonA trend is facing the theoretical limit even with the FP technology. Assist Gate (AG) structure was proposed to improve the RonA and turn-off loss Eoff tradeoff, because the channel and drift resistances can be reduced with avoiding the Cgd 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 Eon 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.