Analog circuit and semiconductor device
View Patent ↗An object is to obtain a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range, using a thin film transistor in which an oxide semiconductor layer is used. An analog circuit is formed with the use of a thin film transistor including an oxide semiconductor which has a function as a channel formation layer, has a hydrogen concentration of 5×10 19 atoms/cm 3 or lower, and substantially functions as an insulator in the state where no electric field is generated. Thus, a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range can be obtained.
1. A semiconductor device comprising:
a first transistor; and
a plurality of transistors connected in parallel to each other,
wherein a drain and a gate of the first transistor are electrically connected to each other,
wherein the gate of the first transistor is electrically connected to a gate of one of the plurality of transistors,
wherein each of the first transistor and the plurality of transistors comprises an oxide semiconductor, and
wherein an off-state current of each of the first transistor and the plurality of transistors is 10 −13 A or less.
2. The semiconductor device according to claim 1 , wherein the plurality of transistors have a longer channel width than the first transistor.
3. The semiconductor device according to claim 1 , wherein a channel region of the oxide semiconductor has a carrier concentration of 5×10 14 /cm 3 or lower.
4. The semiconductor device according to claim 1 , further comprising a detector electrically connected to the first transistor.
5. The semiconductor device according to claim 4 , wherein the detector is any of a photo-sensor, an audio sensor and a temperature sensor.
6. A display device comprising the semiconductor device according to claim 1 .
7. An electronic appliance comprising the semiconductor device according to claim 1 .
8. A semiconductor device comprising:
a first transistor; and
a plurality of transistors connected in parallel to each other,
wherein a drain and a gate of the first transistor are electrically connected to each other,
wherein the gate of the first transistor is electrically connected to a gate of one of the plurality of transistors,
wherein each of the first transistor and the plurality of transistors comprises an oxide semiconductor, and
wherein the oxide semiconductor has a hydrogen concentration of 5×10 19 atoms/cm 3 or lower.
9. The semiconductor device according to claim 8 , wherein the plurality of transistors have a longer channel width than the first transistor.
10. The semiconductor device according to claim 8 , wherein a channel region of the oxide semiconductor has a carrier concentration of 5×10 14 /cm 3 or lower.
11. The semiconductor device according to claim 8 , further comprising a detector electrically connected to the first transistor.
12. The semiconductor device according to claim 11 , wherein the detector is any of a photo-sensor, an audio sensor and a temperature sensor.
13. A display device comprising the semiconductor device according to claim 8 .
14. An electronic appliance comprising the semiconductor device according to claim 8 .
15. A semiconductor device comprising:
a first transistor;
a second transistor;
a capacitor;
a light-emitting element;
a first line; and
a second line,
wherein one of a source and a drain of the first transistor is electrically connected to the first line,
wherein the other one of the source and the drain of the first transistor is electrically connected to a gate of the second transistor and one terminal of the capacitor,
wherein the other one terminal of the capacitor is electrically connected to one of a source and a drain of the second transistor and the light-emitting element,
wherein the other one of the source and the drain of the second transistor is electrically connected to the second line,
wherein each of the first transistor and the second transistor comprises an oxide semiconductor, and
wherein an off-state current of each of the first transistor and the second transistor is 10 −13 A or less.
16. The semiconductor device according to claim 15 , wherein the oxide semiconductor has a hydrogen concentration of 5×10 19 atoms/cm 3 or lower.
17. The semiconductor device according to claim 15 , wherein a channel region of the oxide semiconductor has a carrier concentration of 5×10 14 /cm 3 or lower.
18. The semiconductor device according to claim 15 , further comprising:
a third transistor;
a fourth transistor; and
a third line,
wherein one of a source and a drain of the third transistor is electrically connected to the first line,
wherein a gate of the first transistor and a gate of the third transistor are electrically connected to the third line,
wherein the other one of the source and the drain of the third transistor is electrically connected to one of a source and a drain of the fourth transistor,
wherein the other one of the source and the drain of the fourth transistor is electrically connected to the other one terminal of the capacitor, the one of the source and the drain of the second transistor, and the light-emitting element,
wherein a gate of the fourth transistor is electrically connected to the other one of the source and the drain of the first transistor, the gate of the second transistor, and the one terminal of the capacitor, and
wherein each of the third transistor and the fourth transistor comprises the oxide semiconductor.
19. A display device comprising the semiconductor device according to claim 15 .
20. An electronic appliance comprising the semiconductor device according to claim 15 .