Abstract: According to one embodiment, a semiconductor device includes: a first nitride semiconductor layer provided on a substrate; a second nitride semiconductor layer provided on the first nitride semiconductor layer and having a band gap wider than that of the first nitride semiconductor layer; a source electrode and a drain electrode, being provided on the second nitride semiconductor layer separately from each other; a gate electrode provided on the second nitride semiconductor layer and arranged between the source electrode and the drain electrode; a first field plate electrode provided on the second nitride semiconductor layer, arranged between the gate electrode and the drain electrode, and electrically coupled to the source electrode; and a second field plate electrode provided on the first field plate electrode and formed to project toward the gate electrode.

Abstract: According to one embodiment, a semiconductor device includes an n-layer and a p-layer arranged in a vertical trench structure in a drift layer. A depletion layer is formed to a depth of a trench of the vertical trench structure after a depletion layer spreads in a lateral direction between the n-layer and the p-layer when a voltage is applied between a drain and a source. A method for controlling the semiconductor device comprises detecting a voltage value between the drain and the source of the semiconductor device at turn-off and reducing a current value of a gate discharge current discharged from a gate in a first period. The first period starting before the detected voltage value greatly changes.

Abstract: An optical coupling device includes a light receiving element provided with a first output terminal and a second output terminal, a light emitting element provided on the light receiving element, a first switching element, a first electrode plate, and a sealing member. The first switching element is provided side by side on the light receiving element. A first main terminal and a control terminal are provided on an upper surface of the first switching element. A second main terminal is provided on a lower surface of the first switching element. The first main terminal is connected to the first output terminal. The control terminal is connected to the second output terminal. An upper surface of the first electrode plate is connected to the second main terminal. The sealing member covers the light receiving element, the light emitting element, and the first switching element.

Abstract: An optical coupling device includes a light receiving element provided with a first output terminal and a second output terminal, a light emitting element provided on the light receiving element, a first switching element, a first electrode plate, and a sealing member. The first switching element is provided side by side on the light receiving element. A first main terminal and a control terminal are provided on an upper surface of the first switching element. A second main terminal is provided on a lower surface of the first switching element. The first main terminal is connected to the first output terminal. The control terminal is connected to the second output terminal. An upper surface of the first electrode plate is connected to the second main terminal. The sealing member covers the light receiving element, the light emitting element, and the first switching element.

Abstract: A power conversion device includes: a first power conversion circuit that converts power inputted from outside and outputs the converted power to a second power conversion circuit connected to the first power conversion circuit via a DC link, which outputs the converted power to a load; smoothing capacitors provided in an output part of the first power conversion circuit and an input part of the second power conversion circuit; a first and second common mode current extraction circuits provided in an input part of the first power conversion and second power conversion circuits; and a virtual neutral potential line that connects the first and second common mode current extraction circuits; a DC link filter circuit that includes a Y-shaped capacitor connected between the DC link part and the virtual neutral potential line.

Abstract: A power conversion device includes: a first power conversion circuit that converts power inputted from outside and outputs the converted power to a second power conversion circuit connected to the first power conversion circuit via a DC link, which outputs the converted power to a load; smoothing capacitors provided in an output part of the first power conversion circuit and an input part of the second power conversion circuit; a first and second common mode current extraction circuits provided in an input part of the first power conversion and second power conversion circuits; and a virtual neutral potential line that connects the first and second common mode current extraction circuits; a DC link filter circuit that includes a Y-shaped capacitor connected between the DC link part and the virtual neutral potential line.

Abstract: A semiconductor device according to an embodiment includes a normally-off transistor having a first source, a first drain, and a first gate; a normally-on transistor having a second source electrically connected to the first drain, a second drain, and a second gate, a capacitor having a first end and a second end, the second end being electrically connected to the second gate, a first diode having a first anode electrically connected between the second end and the second gate and having a first cathode electrically connected to the second source, a first resistor provided between the first end and the first gate, and a second diode having a second anode electrically connected to the first end and having a second cathode electrically connected to the first gate, the second diode being provided in parallel with the first resistor.

Abstract: A switching unit of an embodiment includes a first switching element of normally-on type, a second switching element of normally-off type having a non-reference potential side conductive terminal connected to a reference potential side conductive terminal of the first switching element, a resistive element having one end connected to a conduction control terminal of the first switching element; a series capacitor connected between the other end of the resistive element and a conduction control terminal of the second switching element; and a diode having an anode connected to the other end of the resistive element and a cathode connected to a common junction of the first switching element and the second switching element.

Abstract: A switching device includes first and switching elements connected in series, a capacitor connected to a gate of the first switching element, a diode having an anode connected between the capacitor and the gate of the first switching element and a cathode connected to a source of the first switching element. A capacitance of the capacitor is equal to or greater than a value calculated by a predetermined expression.

Abstract: A switching device includes first and switching elements connected in series, a capacitor connected to a gate of the first switching element, a diode having an anode connected between the capacitor and the gate of the first switching element and a cathode connected to a source of the first switching element. A capacitance of the capacitor is equal to or greater than a value calculated by a predetermined expression.

Abstract: A switching unit of an embodiment includes a first switching element of normally-on type, a second switching element of normally-off type having a non-reference potential side conductive terminal connected to a reference potential side conductive terminal of the first switching element, a resistive element having one end connected to a conduction control terminal of the first switching element; a series capacitor connected between the other end of the resistive element and a conduction control terminal of the second switching element; and a diode having an anode connected to the other end of the resistive element and a cathode connected to a common junction of the first switching element and the second switching element.

Abstract: A semiconductor device according to an embodiment includes a normally-off transistor having a first source, a first drain, and a first gate; a normally-on transistor having a second source electrically connected to the first drain, a second drain, and a second gate, a capacitor having a first end and a second end, the second end being electrically connected to the second gate, a first diode having a first anode electrically connected between the second end and the second gate and having a first cathode electrically connected to the second source, a first resistor provided between the first end and the first gate, and a second diode having a second anode electrically connected to the first end and having a second cathode electrically connected to the first gate, the second diode being provided in parallel with the first resistor.

Abstract: A switching unit of an embodiment includes a first switching element of normally-on type, a second switching element of normally-off type having a non-reference potential side conductive terminal connected to a reference potential side conductive terminal of the first switching element, a series capacitor connected between a conduction control terminal of the first switching element and a conduction control terminal of the second switching element, and a diode having an anode connected to the conduction control terminal of the first switching element and a cathode connected to a common junction of the first switching element and the second switching element.

Abstract: A switching unit of an embodiment includes a first switching element of normally-on type, a second switching element of normally-off type having a non-reference potential side conductive terminal connected to a reference potential side conductive terminal of the first switching element, a series capacitor connected between a conduction control terminal of the first switching element and a conduction control terminal of the second switching element, and a diode having an anode connected to the conduction control terminal of the first switching element and a cathode connected to a common junction of the first switching element and the second switching element.

Abstract: According to one embodiment, a power supply device includes a substrate, a first inductor, and a second inductor. The substrate has a first surface and a second surface on opposite side from the first surface. The first inductor includes a first coil having a coil center axis substantially parallel to a first direction, is used for a switching circuit for controlling power supplied to a load, and is mounted on the first surface of the substrate. The second inductor includes a second coil having a coil center axis substantially parallel to the first direction, is electrically connected to the first inductor, and is mounted on the second surface of the substrate. As viewed in a direction orthogonal to the first surface, position of the first coil of the first inductor does not overlap position of the second coil of the second inductor.