DC-DC CONVERTER, POWER SUPPLY CIRCUIT, AND SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a DC-DC converter for improving the power conversion efficiency.

SOLUTION: A transistor functioning as a switching element for controlling the output power includes a back gate electrode for controlling the threshold voltage in addition to a normal gate electrode. It also includes a back gate control circuit for controlling the level of the potential applied to the back gate electrode in accordance with the amount of the output power output from the DC-DC converter. By controlling the potential applied to the back gate electrode with the back gate control circuit, the threshold voltage can be adjusted so that the on resistance is lowered in the case of large output power, and so that the off current is lowered in the case of small output power. Thus, an insulation gate field effect transistor functioning as a switching element with extremely small off current can be provided.

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