Improvement of switching trade-off characteristics between noise and loss in high voltage MOSFETs

A new MOS-gate structure was proposed and demonstrated to improve the switching trade-off characteristics between noise and loss in high-voltage MOSFETs. The lightly p-doped dummy base layer under the gate electrode modulates Cgd-Vds curve due to the depletion under high applied voltage and the turn-off dV/dt can be suppressed even with high-speed switching. The fabricated device showed the surge voltage suppression of 50 V or the turn-off loss reduction of 20% in the turn-off switching test with an inductive load. In the flyback converter operation, it was also shown that the trade-off characteristics between the radiation noise and total power loss were improved by the proposed dummy base structure.