Semiconductor device and display device including the same

• US 8,610,696 B2
• Filed: 02/04/2011
• Issued: 12/17/2013
• Est. Priority Date: 02/12/2010
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kurokawa, Yoshiyuki
• Primary Examiner(s): NGUYEN, KIMNHUNG T
• Application Number:
  US13/020,829
• Publication Number:
  US 20110199351A1
• Time in Patent Office: 1,047 Days
• Field of Search: 345 87-100, 345204-207, 326/104, 326/108, 326/112, 326/114
• US Class Current: 345/207
• CPC Class Codes: G09G 2360/142 the light being detected by light detection means within each pixel
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: H01L 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H03K 5/2472 using field effect transistors H03K5/2436 takes precedence
• CPC Class Codes: H03M 1/46 with digital/analogue converter for supplying reference values to converter

Abstract

A semiconductor circuit including: an A/D converter circuit which converts an inputted first signal into a second signal. The A/D converter circuit includes a comparator circuit which compares a voltage of the first signal and a reference voltage; an A/D conversion controller circuit which outputs a digital signal in accordance with comparison results given by the comparator circuit, as a fourth signal and which outputs, in accordance with the third signal, a digital signal corresponding to the first signal, as the second signal; and a D/A converter which converts an inputted fourth signal into an analog signal and which outputs the analog signal as the reference signal. The comparator circuit includes a transistor having a first gate and a second gate. The first signal is inputted to the first gate, the reference signal is inputted to the second gate.

Claims

1. A semiconductor device comprising:

an A/D converter circuit comprising;

a comparator circuit including a transistor having a first gate, a second gate, and a semiconductor layer interposed between the first gate and the second gate;

an A/D conversion controller circuit; and

a D/A converter,

wherein one of a source and a drain of the transistor is electrically connected to an input terminal of the A/D conversion controller circuit,

wherein a first terminal of the A/D conversion controller circuit is electrically connected to an input terminal of the D/A converter,

wherein an output terminal of the D/A converter is electrically connected to the second gate of the transistor, and

wherein the first gate of the transistor is an input terminal of the A/D converter circuit.

2. The semiconductor device according to claim 1,

wherein the semiconductor layer is an oxide semiconductor layer.

3. The semiconductor device according to claim 2,

wherein a carrier concentration of the oxide semiconductor layer is less than 1 ×

10¹⁴/cm³.

4. The semiconductor device according to claim 1,

wherein a second terminal of the A/D conversion controller circuit is an output terminal of the A/D converter circuit.

5. A display device including the semiconductor device according to claim 1, a pixel circuit, and a driver circuit for controlling the pixel circuit.

6. A semiconductor device comprising:

a photoelectric conversion circuit; and

an A/D converter circuit comprising;

a comparator circuit including a transistor having a first gate, a second gate, and a semiconductor layer interposed between the first gate and the second gate;

an A/D conversion controller circuit; and

a D/A converter,

wherein one of a source and a drain of the transistor is electrically connected to an input terminal of the A/D conversion controller circuit,

wherein a first terminal of the A/D conversion controller circuit is electrically connected to an input terminal of the D/A converter,

wherein an output terminal of the D/A converter is electrically connected to the second gate of the transistor, and

wherein the first gate of the transistor is electrically connected to the photoelectric conversion circuit.

7. The semiconductor device according to claim 6,

wherein the semiconductor layer is an oxide semiconductor layer.

8. The semiconductor device according to claim 7,

wherein a carrier concentration of the oxide semiconductor layer is less than 1 ×

10¹⁴/cm³.

9. The semiconductor device according to claim 6,

wherein a second terminal of the A/D conversion controller circuit is an output terminal of the A/D converter circuit.

10. A display device including the semiconductor device according to claim 6, a pixel circuit, and a driver circuit for controlling the pixel circuit.

11. The display device according to claim 10,

wherein the pixel circuit and the photoelectric conversion circuit are included in a display portion.

12. A semiconductor device comprising:

an A/D converter circuit comprising;

a comparator circuit including a transistor having a first gate, a second gate, and a semiconductor layer interposed between the first gate and the second gate;

an A/D conversion controller circuit; and

a D/A converter,

wherein the comparator circuit is configured to compare a voltage of a first signal inputted to the first gate of the transistor and a threshold voltage of the transistor and to output a second signal corresponding to comparison results to the A/D conversion controller circuit,

wherein the A/D conversion controller circuit is configured to output a third signal corresponding to the second signal to the D/A converter, and

wherein the D/A converter is configured to convert the third signal into an analog signal and to output the analog signal to the second gate of the transistor so as to change the threshold voltage of the transistor.

13. The semiconductor device according to claim 12,

wherein the semiconductor layer is an oxide semiconductor layer.

14. The semiconductor device according to claim 13,

wherein a carrier concentration of the oxide semiconductor layer is less than 1 ×

10¹⁴/cm³.

15. The semiconductor device according to claim 12,

wherein the A/D conversion controller circuit is configured to output a digital signal having a digital value corresponding to the first signal.

16. A display device including the semiconductor device according to claim 12, a pixel circuit, and a driver circuit for controlling the pixel circuit.

17. A semiconductor device comprising:

a photoelectric conversion circuit; and

an A/D converter circuit comprising;

a comparator circuit including a transistor having a first gate, a second gate, and a semiconductor layer interposed between the first gate and the second gate;

an A/D conversion controller circuit; and

a D/A converter,

wherein the photoelectric conversion circuit is configured to output a first signal to the first gate of the transistor,

wherein the comparator circuit is configured to compare a voltage of the first signal inputted to the first gate of the transistor and a threshold voltage of the transistor and to output a second signal corresponding to comparison results to the A/D conversion controller circuit,

wherein the A/D conversion controller circuit is configured to output a third signal corresponding to the second signal to the D/A converter, and

wherein the D/A converter is configured to convert the third signal into an analog signal and to output the analog signal to the second gate of the transistor so as to change the threshold voltage of the transistor.

18. The semiconductor device according to claim 17,

wherein the semiconductor layer is an oxide semiconductor layer.

19. The semiconductor device according to claim 18,

wherein a carrier concentration of the oxide semiconductor layer is less than 1 ×

10¹⁴/cm³.

20. The semiconductor device according to claim 17,

wherein the A/D conversion controller circuit is configured to output a digital signal having a digital value corresponding to the first signal.

21. A display device including the semiconductor device according to claim 17, a pixel circuit, and a driver circuit for controlling the pixel circuit.

22. The display device according to claim 21,

wherein the pixel circuit and the photoelectric conversion circuit are included in a display portion.