| 摘要 |
PROBLEM TO BE SOLVED: To provide a memory device that can suppress power consumption without requiring a complicated manufacturing process.SOLUTION: A memory device includes a first memory circuit which is volatile, and a second memory circuit which is nonvolatile and which has a transistor whose channel is formed in an oxide semiconductor layer. When driving at high frequency, in a period of supply of power source voltage, a data signal is written in the first memory circuit and output from the first memory circuit, and in a part of the period of supply of the power source voltage, which is a period before stopping supply of the power source voltage, the data signal is written in the second memory circuit. When driving at low frequency, in the period of supply of power source voltage, the data signal is written in the second memory circuit, the data signal written in the second memory circuit is written in the first memory circuit, and the data signal written in the first memory circuit is output.SELECTED DRAWING: Figure 1 |
