Abstract: An accumulation-mode power MOSFET includes a trenched gate that is formed in a semiconductor material of a first conductivity type. A region of second conductivity type is formed in the substrate (which may include an epitaxial layer) and a PN junction formed by the region of second conductivity type is connected in parallel with the current path through the accumulation-mode MOSFET. The diode is designed to have a breakdown voltage was causes the diode to break down before the oxide layer surrounding the gate can be ruptured or otherwise damaged when the MOSFET is in an off condition.

Abstract: One or more diodes are integrated with a trenched gate accumulation-mode MOSFET to provide protection for the gate oxide layer. In a preferred embodiment, a first pair of diodes are formed in a series connection between the source and the gate of the MOSFET. A third diode may be added to provide a series diode pair between the drain and the gate of the MOSFET. A pair of accumulation-mode MOSFETs may be formed in a single chip to provide a push-pull halfbridge circuit, and a multiple-phase motor driver may be fabricated in two chips, with the high side MOSFETs being formed in one chip and the low side MOSFETs being formed in the other chip. The accumulation-mode MOSFET may be used as an AC switch by connecting its gate to a gate bias circuit which finds the lower of the source and drain voltages of the accumulation-mode MOSFET.