DC converter circuit and power supply circuit

摘要

A DC converter circuit having high reliability is provided. The DC converter circuit includes: an inductor configured to generate electromotive force in accordance with a change in flowing current; a transistor including a gate, a source, and a drain, which is configured to control generation of the electromotive force in the inductor by being on or off; a rectifier in a conducting state when the transistor is off; and a control circuit configured to control on and off of the transistor. The transistor includes an oxide semiconductor layer whose hydrogen concentration is less than or equal to 5×1019 atoms/cm3 as a channel formation layer.

主权项

1. A power supply circuit comprising:
an inductor comprising a terminal; a transistor connected to the terminal of the inductor, the transistor comprising:
a first conductive film over a first insulating layer, the first conductive film functioning as one of a source electrode and a drain electrode;an oxide semiconductor layer over the first conductive film;a second conductive film over the oxide semiconductor layer, the second conductive film functioning as the other of the source electrode and the drain electrode; anda gate electrode over the second conductive film, a rectifier connected to the terminal of the inductor; and a control circuit connected to the transistor, wherein a hydrogen concentration of the oxide semiconductor layer is less than or equal to 5×1019 atoms/cm3, and wherein, in a top view of the transistor, the gate electrode includes a concentric circular shape having an opening overlapping the second conductive film.