Low on-resistance SOI power MOSFET using dynamic threshold (DT) concept for high efficient DC-DC converter

A new low on-resistance (R_on) power MOSFET using the dynamic threshold (DT) concept was studied. The R_on at low gate-driving-voltage was effectively improved using the DT concept. We carried out numerical simulations based on the experimental measurements. It was clarified that the R_on of the thin-film DT-SOI power MOSFET was 30% lower than that of conventional thin-film SOI power MOSFETs at a gate voltage of 1.2 V. Although the R_on of the DT-SOI device was lower, the total gate charge was slightly larger than that of conventional devices because of an additional device structure. The lower R_on reduces the power loss of a synchronous rectifier while the larger gate charge increases it. We compared the power loss of the thin-film DT-DOI device as the synchronous rectifier of a DC-DC converter with that of a conventional thin-film SOI device. It was clarified that the power loss of the new power MOSFET was 36% lower than that of the conventional thin-film SOI device at a gate voltage of 1.2 V