Semiconductor device
A semiconductor device that is less influenced by variations in characteristics between transistors or variations in a load, and is efficient even for normally-on transistors is provided. The semiconductor device includes at least a transistor, two wirings, three switches, and two capacitors. A first switch controls conduction between a first wiring and each of a first electrode of a first capacitor and a first electrode of a second capacitor. A second electrode of the first capacitor is connected to a gate of the transistor. A second switch controls conduction between the gate and a second wiring. A second electrode of the second capacitor is connected to one of a source and a drain of the transistor. A third switch controls conduction between the one of the source and the drain and each of the first electrode of the first capacitor and the first electrode of the second capacitor.
1. A method for driving a semiconductor device comprising a transistor, first and second switches, first and second capacitors, and a light-emitting element, comprising the steps of:
initializing the transistor and the first capacitor while the first and second switches are on;
acquiring a threshold voltage of the transistor in the first capacitor while the first switch is off and the second switch is on;
supplying a signal to the second capacitor through the first switch while the second switch is off; and
lighting the light-emitting element,
wherein a terminal of the first switch is electrically connected to a first electrode of the first capacitor, a first electrode of the second capacitor, and a first terminal of the second switch,
wherein a second electrode of the first capacitor is electrically connected to a gate of the transistor, and
wherein a terminal of the transistor is electrically connected to a second electrode of the second capacitor, a second terminal of the second switch, and the light-emitting element.
2. The method according to claim 1 , wherein a sum of a voltage across the first capacitor and the second capacitor is equal to a gate-source voltage of the transistor.
3. The method according to claim 1 , further comprising:
initializing a potential of the terminal of the transistor before the supplying.
4. The method according to claim 1 , wherein a length of a period of the supplying is smaller than a length of a period of the initializing.
5. The method according to claim 1 , wherein a length of a period of the supplying is smaller than a length of a period of the acquiring.
6. The method according to claim 1 , wherein a capacitance of the first capacitor is higher than or equal to a capacitance of the second capacitor.
7. A method for driving a semiconductor device comprising a transistor, first and second switches, first and second capacitors, and a light-emitting element, comprising the steps of:
initializing the transistor and the first capacitor while the first and second switches are on;
releasing electric charge of the first capacitor through the transistor and acquiring a threshold voltage of the transistor in the first capacitor while the first switch is off and the second switch is on;
supplying a signal to the second capacitor through the first switch while the second switch is off; and
lighting the light-emitting element electrically connected to the transistor,
wherein a first electrode of the first capacitor is electrically connected to a gate of the transistor,
wherein a second electrode of the first capacitor is electrically connected to a first electrode of the second capacitor,
wherein a second electrode of the second capacitor is electrically connected to a terminal of the transistor, and
wherein the second switch is electrically connected between the terminal of the transistor and the second electrode of the first capacitor.
8. The method according to claim 7 , wherein a sum of a voltage across the first capacitor and the second capacitor is equal to a gate-source voltage of the transistor.
9. The method according to claim 7 , further comprising:
initializing a potential of the terminal of the transistor before the supplying.
10. The method according to claim 7 , wherein a length of a period of the supplying is smaller than a length of a period of the initializing.
11. The method according to claim 7 , wherein a length of a period of the supplying is smaller than a length of a period of the releasing and acquiring.
12. The method according to claim 7 , wherein a capacitance of the first capacitor is higher than or equal to a capacitance of the second capacitor.