Semiconductor device, and display device and electronic device utilizing the same
View Patent ↗A semiconductor device having a normal function means is provided, in which the amplitude of an output signal is prevented from being decreased even when a digital circuit using transistors having one conductivity is employed. By turning OFF a diode-connected transistor 101 , the gate terminal of a first transistor 102 is brought into a floating state. At this time, the first transistor 102 is ON and its gate-source voltage is stored in a capacitor. Then, when a potential at the source terminal of the first transistor 102 is increased, a potential at the gate terminal of the first transistor 102 is increased as well by bootstrap effect. As a result, the amplitude of an output signal is prevented from being decreased.
1. A semiconductor device comprising a first transistor, a second transistor, a third transistor, a first input terminal, and a second input terminal, said semiconductor device characterized in that:
wherein a source of the first transistor is electrically connected to a drain of the second transistor,
a drain of the third transistor is electrically connected to a gate of the first transistor,
the first input terminal is electrically connected to a gate of the third transistor and to a gate of the second transistor, and
the second input terminal is electrically connected to the gate of the first transistor through a rectifying element.
2. The semiconductor device according to claim 1 , wherein the rectifying element is a diode-connected transistor.
3. The semiconductor device according to claim 2 , wherein the diode-connected transistor as the rectifying element and the first transistor have the same conductivity.
4. The semiconductor device according to claim 2 , wherein a second rectifying element is electrically connected in series to the third transistor.
5. The semiconductor device according to claim 4 , wherein the second rectifying element is a diode-connected transistor.
6. The semiconductor device according to claim 5 , wherein the diode-connected transistor as the second rectifying element and the first transistor have the same conductivity.
7. The semiconductor device according to claim 1 , wherein a second rectifying element is electrically connected in series to the third transistor.
8. The semiconductor device according to claim 7 , wherein the second rectifying element is a diode-connected transistor.
9. The semiconductor device according to claim 8 , wherein the diode-connected transistor as the second rectifying element and the first transistor have the same conductivity.
10. A display device comprising the semiconductor device according to claim 1 .
11. An electronic device comprising the display device according to claim 10 .
12. A semiconductor device comprising a first transistor, a second transistor, a third transistor, a first input terminal, a second input terminal, and a capacitor,
wherein a source of the first transistor is electrically connected to a drain of the second transistor,
a drain of the third transistor is electrically connected to a gate of the first transistor,
the first input terminal is electrically connected to a gate of the third transistor and to a gate of the second transistor,
the second input terminal is electrically connected to the gate of the first transistor through a rectifying element,
either terminal of the capacitor is electrically connected to the gate of the first transistor, and
the other terminal of the capacitor is electrically connected to the source of the first transistor.
13. The semiconductor device according to claim 12 , wherein the rectifying element is a diode-connected transistor.
14. The semiconductor device according to claim 13 , wherein the diode-connected transistor as the rectifying element and the first transistor have the same conductivity.
15. The semiconductor device according to claim 13 , wherein a second rectifying element is electrically connected in series to the third transistor.
16. The semiconductor device according to claim 15 , wherein the second rectifying element is a diode-connected transistor.
17. The semiconductor device according to claim 16 , wherein the diode-connected transistor as the second rectifying element and the first transistor have the same conductivity.
18. The semiconductor device according to claim 12 , wherein a second rectifying element is electrically connected in series to the third transistor.
19. The semiconductor device according to claim 18 , wherein the second rectifying element is a diode-connected transistor.
20. The semiconductor device according to claim 19 , wherein the diode-connected transistor as the second rectifying element and the first transistor have the same conductivity.
21. A display device comprising the semiconductor device according to claim 12 .
22. An electronic device comprising the display device according to claim 21 .
23. An electronic device including a circuit comprising:
a first transistor;
a second transistor whose drain is electrically connected to a source of the first transistor;
a third transistor whose drain is electrically connected to a gate of the first transistor;
a first input terminal which is electrically connected to a gate of the second transistor and to a gate of the third transistor; and
a second input terminal which is electrically connected to the gate of the first transistor through a rectifying element.
24. The electronic device according to claim 23 , wherein the rectifying element is a diode-connected transistor.
25. The electronic device according to claim 23 wherein said electronic device is a light emitting device.
26. The electronic device according to claim 23 wherein said electronic device is a digital still camera.
27. The electronic device according to claim 23 wherein said electronic device is a computer.
28. The electronic device according to claim 23 wherein said electronic device is a video camera.
29. The electronic device according to claim 23 wherein said electronic device is a cellular phone.
30. The electronic device according to claim 23 , further comprising a second rectifying element which is interposed between the gate of the first transistor and the drain of the third transistor.
31. An electronic device including a circuit comprising:
a first transistor;
a second transistor whose drain is electrically connected to a source of the first transistor;
a third transistor whose drain is electrically connected to a gate of the first transistor;
a first input terminal which is electrically connected to a gate of the second transistor and to a gate of the third transistor;
a second input terminal which is electrically connected to the gate of the first transistor through a rectifying element; and
a capacitor which is electrically connected between the gate and the source of the first transistor.
32. The electronic device according to claim 31 , wherein the rectifying element is a diode-connected transistor.
33. The electronic device according to claim 31 wherein said electronic device is a light emitting device.
34. The electronic device according to claim 31 wherein said electronic device is a digital still camera.
35. The electronic device according to claim 31 wherein said electronic device is a computer.
36. The electronic device according to claim 31 wherein said electronic device is a video camera.
37. The electronic device according to claim 31 wherein said electronic device is a cellular phone.
38. The electronic device according to claim 31 , further comprising a second rectifying element which is interposed between the gate of the first transistor and the drain of the third transistor.