Memory device and electronic device
A memory device having long data retention time and high reliability is provided. The memory device includes a driver circuit and a plurality of memory cells, the memory cell includes a transistor and a capacitor, and the transistor includes a metal oxide in a channel formation region. The transistor includes a first gate and a second gate, and in a period during which the memory cell retains data, negative potentials are applied to the first gate and the second gate of the transistor.
1. A semiconductor device comprising:
a driver circuit;
a first negative potential generation circuit,
a second negative potential generation circuit, and
a plurality of memory cells,
wherein each memory cell comprises a transistor and a capacitor,
wherein one of a source and a drain of the transistor is electrically connected to one electrode of the capacitor,
wherein the transistor comprises a first metal oxide in a first channel formation region,
wherein the transistor comprises a first gate and a second gate,
wherein the first gate and the second gate have a region overlapping each other with the first channel formation region therebetween,
wherein the driver circuit is configured to drive the first gate,
wherein the driver circuit comprises a level shifter and a buffer,
wherein the buffer is electrically connected to a wiring,
wherein the wiring is electrically connected to the first gate,
wherein the first negative potential generation circuit has a function of supplying a first negative potential to the first gate,
wherein the second negative potential generation circuit has a function of supplying a second negative potential to the second gate.
2. The semiconductor device according to claim 1 ,
wherein the second negative potential is lower than the first negative potential.
3. The semiconductor device according to claim 1 ,
wherein the first negative potential generation circuit comprises a first ring oscillator, a first charge pump, and a first comparator,
wherein the second negative potential generation circuit comprises a second ring oscillator, a second charge pump, and a second comparator.
4. An electronic device comprising the semiconductor device according to claim 1 .
5. The semiconductor device according to claim 3 ,
wherein the first comparator comprise a second transistor,
wherein the second transistor comprises a second metal oxide in a second channel formation region,
wherein the second comparator comprise a third transistor,
wherein the third transistor comprises a third metal oxide in a third channel formation region.