Semiconductor device, light-emitting device, and electronic device
An object is to prevent an operation defect and to reduce an influence of fluctuation in threshold voltage of a field-effect transistor. A field-effect transistor, a switch, and a capacitor are provided. The field-effect transistor includes a first gate and a second gate which overlap with each other with a channel formation region therebetween, and the threshold voltage of the field-effect transistor varies depending on the potential of the second gate. The switch has a function of determining whether electrical connection between one of a source and a drain of the field-effect transistor and the second gate of the field-effect transistor is established. The capacitor has a function of holding a voltage between the second gate of the field-effect transistor and the other of the source and the drain of the field-effect transistor.
1. A light-emitting device comprising:
a first transistor, a second transistor, a third transistor, and a fourth transistor, a capacitor, and a light-emitting element,
wherein the first transistor includes a first gate electrode, a second gate electrode, and a semiconductor layer including a channel formation region,
wherein the light-emitting element includes a first electrode, a light-emitting layer over the first electrode, and a second electrode over the light-emitting layer,
wherein the first electrode of the light-emitting element includes a region overlapping with the first gate electrode and overlapping with the second gate electrode,
wherein the first transistor includes a function of supplying current to the light-emitting element,
wherein the first gate electrode includes a region overlapping with the second gate electrode through the channel formation region,
wherein, in a channel length direction of the first transistor, a width of the second gate electrode is larger than a width of the first gate electrode,
wherein the first gate electrode is electrically connected to a first electrode of the capacitor,
wherein a second electrode of the capacitor is electrically connected to a first wiring through the second transistor,
wherein the second gate electrode is electrically connected to a second wiring through the third transistor,
wherein the first wiring includes a function of supplying a data signal,
wherein the second wiring includes a function of supplying a potential,
wherein one of a source and a drain of the first transistor is electrically connected to a third wiring through the fourth transistor,
wherein the other of the source and the drain of the first transistor is electrically connected to the first wiring through the second transistor.
2. A light-emitting device comprising:
a first transistor, a second transistor, a third transistor, and a fourth transistor, a capacitor, and a light-emitting element,
wherein the first transistor includes a first gate electrode, a second gate electrode, and a semiconductor layer including a channel formation region,
wherein the light-emitting element includes a first electrode, a light-emitting layer over the first electrode, and a second electrode over the light-emitting layer,
wherein the first electrode of the light-emitting element includes a region overlapping with the first gate electrode and overlapping with the second gate electrode,
wherein the first transistor includes a function of supplying current to the light-emitting element,
wherein the first gate electrode includes a region overlapping with the second gate electrode through the channel formation region,
wherein, in a channel length direction of the first transistor, a width of the second gate electrode is larger than a width of the first gate electrode,
wherein the first gate electrode is electrically connected to a first electrode of the capacitor,
wherein a second electrode of the capacitor is electrically connected to a first wiring through the second transistor,
wherein the second gate electrode is electrically connected to a second wiring through the third transistor,
wherein the first wiring includes a function of supplying a data signal,
wherein the second wiring includes a function of supplying a potential,
wherein one of a source and a drain of the first transistor is electrically connected to a third wiring through the fourth transistor,
wherein the other of the source and the drain of the first transistor is electrically connected to the first wiring through the second transistor,
wherein a gate electrode of the second transistor is electrically connected to a fourth wiring,
wherein a gate electrode of the third transistor is electrically connected to a fifth wiring,
wherein the channel formation region of the first transistor is located between the fourth wiring and the fifth wiring.
3. The light-emitting device according to claim 1 , wherein, in a period in which the third transistor is off and the fourth transistor is on, a current corresponding to the data signal is supplied to the light-emitting element.
4. The light-emitting device according to claim 2 , wherein, in a period in which the third transistor is off and the fourth transistor is on, a current corresponding to the data signal is supplied to the light-emitting element.