| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device that allows efficient refresh to be performed.SOLUTION: The semiconductor device includes: a circuit including a memory cell including a transistor using an oxide semiconductor; and a refresh timing determination unit 100 including a capacitor, a transistor 101 using an oxide semiconductor, and a comparator circuit 103. The potential of a floating node in the refresh timing determination unit is directly or indirectly input to the comparator circuit and compared with a reference potential VERF. When the potential of the floating node becomes a certain value, power switches 104, 105 operating in accordance with an output of the comparator circuit are turned on, power is supplied to the circuit 108 including the memory cell, and then the reference potential is also changed. After that, refresh operation of the memory cell is performed. When the refresh operation is finished, the power switches are turned off. |
