Solid-state imaging device, method of driving the same, and electronic apparatus
The present technology relates to a solid-state imaging device that can improve imaging quality by reducing variation in the voltage of a charge retention unit, a method of driving the solid-state imaging device, and an electronic apparatus. A first photoelectric conversion unit generates and accumulates signal charge by receiving light that has entered a pixel, and photoelectrically converting the light. A first charge retention unit retains the generated signal charge. A first output transistor outputs the signal charge in the first charge retention unit as a pixel signal, when the pixel is selected by the first select transistor. A first voltage control transistor controls the voltage of the output end of the first output transistor. The present technology can be applied to pixels in solid-state imaging devices, for example.
1. An imaging device comprising:
a pixel including:
a first photoelectric conversion unit;
a floating diffusion coupled to the first photoelectric conversion unit;
a first transistor, one of a source or a drain of the first transistor being coupled to the floating diffusion;
a second transistor, a gate of the second transistor being coupled to the floating diffusion;
a third transistor, one of a source or a drain of the third transistor being coupled to one of a source or a drain of the second transistor; and
a fourth transistor, one of a source or a drain of the fourth transistor being coupled to a node between the second transistor and the third transistor,
wherein the other of the source or the drain of the first transistor and the other of the source or the drain of the fourth transistor are configured to have a same potential,
wherein the second transistor and the fourth transistor have a same channel type.
2. The imaging device according to claim 1 , wherein the first photoelectric conversion unit is configured to photoelectrically convert green light.
3. The imaging device according to claim 1 , wherein the first photoelectric conversion unit comprises a photoelectric conversion film interposed between an upper electrode and a lower electrode.
4. The imaging device according to claim 3 , wherein the photoelectric conversion film is one of an organic photoelectric conversion film and an inorganic photoelectric conversion film.
5. The imaging device according to claim 1 , wherein the pixel further comprises a color filter disposed above the first photoelectric conversion unit.
6. The imaging device according to claim 5 , wherein the first photoelectric conversion unit is configured to photoelectrically convert red, green or blue light that has passed through the color filter.
7. The imaging device according to claim 1 , wherein the first transistor is configured to reset a potential of the floating diffusion.
8. The imaging device according to claim 1 , wherein the second transistor is configured to output a pixel signal in accordance with a potential of the floating diffusion.
9. The imaging device according to claim 1 , wherein the third transistor is configured to output a pixel signal of the pixel to an analog-to-digital (AD) converter via a column signal line.
10. The imaging device according to claim 1 , wherein the fourth transistor is configured to control a potential of the node between the second transistor and the third transistor.
11. The imaging device according to claim 1 , wherein the fourth transistor is configured to be in an off-state while the third transistor is in an on-state.
12. The imaging device according to claim 1 , wherein the fourth transistor is configured to be in an on-state while the third transistor is in an off-state.
13. The imaging device according to claim 1 , wherein the other of the source or the drain of the first transistor and the other of the source or the drain of the fourth transistor are coupled to a node that receives a power supply voltage.
14. The imaging device according to claim 1 , wherein the floating diffusion is disposed at a surface of a semiconductor substrate, the semiconductor substrate being disposed below the first photoelectric conversion unit and the surface being at a light incident side of the semiconductor substrate.
15. The imaging device according to claim 14 , further comprising metal wirings disposed between the first photoelectric conversion unit and the semiconductor substrate.
16. The imaging device according to claim 1 , wherein the floating diffusion is disposed at a surface of a semiconductor substrate, the semiconductor substrate being disposed below the first photoelectric conversion unit and the surface being opposite a light incident side of the semiconductor substrate.
17. The imaging device according to claim 16 , further comprising metal wirings, wherein the semiconductor substrate is disposed between the first photoelectric conversion unit and the metal wirings.
18. The imaging device according to claim 16 , wherein the first photoelectric conversion unit is electrically coupled to the floating diffusion via a metal connection conductor which penetrates the semiconductor substrate.
19. The imaging device according to claim 16 , further comprising a second photoelectric conversion unit disposed in the semiconductor substrate.
20. The imaging device according to claim 19 , wherein the second photoelectric conversion unit is configured to photoelectrically convert red or blue light that has passed through the first photoelectric conversion unit.
21. The imaging device according to claim 19 , further comprising a third photoelectric conversion unit disposed in the semiconductor substrate.
22. The imaging device according to claim 21 , wherein one of the second photoelectric conversion unit and the third photoelectric conversion unit is configured to photoelectrically convert red light and the other of the second photoelectric conversion unit and the third photoelectric conversion unit is configured to photoelectrically convert blue light.
23. The imaging device according to claim 21 , wherein at least of a part of the second photoelectric conversion unit overlaps the third photoelectric conversion unit in a cross-sectional view.
24. An electronic apparatus comprising:
an optical unit;
the imaging device according to claim 1 ; and
a digital signal processor circuit.