| 摘要 |
PROBLEM TO BE SOLVED: To inhibit damage of an element even when a high voltage enough to damage the element is applied.SOLUTION: A semiconductor device which operates by input of a first voltage comprises a protection circuit 102 for changing a value of the first voltage when an absolute value of the first voltage is larger than a reference value. The protection circuit includes a control signal creation circuit 121 for creating a second voltage depending on the first voltage and outputting the created second voltage; and a voltage control circuit 122. The voltage control circuit has a source, a drain and a gate, and includes a transistor which controls whether to change the first voltage value depending on a magnitude of a current flowing between the source and the drain when the second voltage is input to the gate as a control signal to cause an on-state or an off-state depending on the second voltage. The transistor further includes an oxide semiconductor layer having a function as a channel formation layer and bandgap of the oxide semiconductor layer is 2 eV and over. |
