Global shutter imaging pixels
View Patent ↗A global shutter imaging pixel may have a single source follower transistor. The source follower transistor may be coupled to a floating diffusion region and a charge storage region. In order to read out samples from the charge storage region without including a second source follower transistor in each pixel, the samples may be transferred to floating diffusion regions of adjacent pixels. Alternatively, a transistor may be configured to transfer charge from the charge storage region to the floating diffusion region of the same pixel, thus reusing a single source follower transistor. These types of pixels may be used for correlated double sampling, where a reset charge level and integration charge level are both sampled. These pixels may also operate in a global shutter mode where images are captured simultaneously by each pixel.
1. An image sensor comprising an array of imaging pixels, wherein each imaging pixel in the array of imaging pixels comprises:
a photodiode;
a floating diffusion region coupled the photodiode;
a source follower transistor coupled to the floating diffusion region;
a charge storage region coupled to the source follower transistor; and
a first transistor, wherein the first transistor is configured to transfer charge from the charge storage region of the imaging pixel to the floating diffusion region of an adjacent imaging pixel.
2. The image sensor defined in claim 1 , wherein each imaging pixel in the array of imaging pixels further comprises:
a second transistor, wherein the second transistor is coupled between the source follower transistor and the charge storage region.
3. The image sensor defined in claim 2 , wherein each imaging pixel in the array of imaging pixels further comprises:
a third transistor, wherein the third transistor is coupled between the photodiode and the floating diffusion region.
4. The image sensor defined in claim 3 , wherein each imaging pixel in the array of imaging pixels further comprises:
a fourth transistor, wherein the fourth transistor is coupled between the floating diffusion region and a bias voltage supply line.
5. The image sensor defined in claim 4 , wherein each imaging pixel in the array of imaging pixels further comprises:
a fifth transistor, wherein the fifth transistor is coupled between the charge storage region and a column line.
6. The image sensor defined in claim 5 , wherein each imaging pixel in the array of imaging pixels further comprises:
a sixth transistor, wherein the sixth transistor is coupled between the photodiode and an additional bias voltage supply line.
7. The image sensor defined in claim 3 , wherein each imaging pixel in the array of imaging pixels further comprises:
a fourth transistor, wherein the fourth transistor is coupled between the charge storage region and the first transistor.
8. The image sensor defined in claim 7 , wherein each imaging pixel in the array of imaging pixels further comprises:
a fifth transistor, wherein the fifth transistor is coupled between the fourth transistor and a column line.
9. The image sensor defined in claim 8 , wherein each imaging pixel in the array of imaging pixels further comprises:
a sixth transistor, wherein the sixth transistor is coupled between the photodiode and a bias voltage supply line.
10. The image sensor defined in claim 1 , wherein the first transistor of each imaging pixel is configured to transfer charge from the charge storage region of the imaging pixel to the floating diffusion region of an adjacent imaging pixel that is in the same column of the array as the imaging pixel.
11. The image sensor defined in claim 1 , wherein the charge storage region of each imaging pixel comprises a component selected from the group consisting of: a storage capacitor, a storage diode, and a storage gate.
12. An image sensor comprising:
a first imaging pixel with a first photosensitive area and a first floating diffusion region;
a second imaging pixel with a second photosensitive region, a second floating diffusion region, a source follower transistor, a charge storage region coupled to the source follower transistor, and at least one transistor configured to transfer charge from the charge storage region to the first floating diffusion region; and
a third imaging pixel with a third photosensitive region, a third floating diffusion region, an additional source follower transistor, an additional charge storage region coupled to the additional source follower transistor, and at least one transistor configured to transfer charge from the additional charge storage region to the second floating diffusion region.
13. The image sensor defined in claim 12 , wherein the first, second, and third imaging pixels are formed in a single column of imaging pixels.
14. The image sensor defined in claim 13 , wherein the second imaging pixel is interposed between the first and third imaging pixels in the single column of imaging pixels.
15. The image sensor defined in claim 12 , wherein the second imaging pixel comprises a reset transistor that is coupled between the second floating diffusion region and a bias voltage supply line.
16. The image sensor defined in claim 12 , wherein the at least one transistor of the second imaging pixel comprises first and second transistors interposed between the charge storage region and the first floating diffusion region, wherein there is a node between the first and second transistors, and wherein the second imaging pixel comprises a reset transistor that is coupled between the node and a column line.
17. An image sensor comprising an array of imaging pixels, wherein each imaging pixel in the array of imaging pixels comprises:
a photosensitive region;
a floating diffusion region coupled the photosensitive region;
a transfer transistor configured to transfer charge from the photosensitive region to the floating diffusion region;
a source follower transistor, wherein the floating diffusion region is coupled to a gate of the source follower transistor;
a storage capacitor coupled to the source follower transistor;
a first transistor coupled between the source follower transistor and the storage capacitor; and
at least one transistor that is coupled between the storage capacitor of the respective imaging pixel and the floating diffusion region of an adjacent imaging pixel.
18. The image sensor defined in claim 17 , wherein each imaging pixel further comprises:
a reset transistor coupled between the floating diffusion region and a bias voltage supply line.
19. The image sensor defined in claim 17 , wherein each imaging pixel further comprises:
a reset transistor coupled between a transistor of the at least one transistor and a column line.
20. The image sensor defined in claim 17 , wherein the at least one transistor of each imaging pixel is coupled between the storage capacitor of the respective imaging pixel and the floating diffusion region of an adjacent imaging pixel in the same column of imaging pixels as the respective imaging pixel.