Image sensors with multiple output structures
View Patent ↗In various embodiments, image sensors incorporate multiple output structures by including multiple sub-arrays, at least one of which includes a region of active pixels, a dark pixel region that is fanned and/or slanted, a dark pixel region that is unfanned and unslanted, a horizontal CCD, and an output structure for conversion of charge to voltage.
1. An image sensor comprising:
two or more pixel sub-arrays each comprising at least one output structure for conversion of charge to voltage, at least one of the sub-arrays comprising:
a region of active pixels each comprising (i) a photo-sensitive region (PSR) for converting light into electrical charge and (ii) a vertical channel for transfer of charge from the PSR,
electrically and directly connected to and positioned below the region of active pixels, a fanned region of dark pixels each (i) comprising a vertical channel for transferring charge and (ii) shielded from incident light,
electrically and directly connected to and positioned below the fanned region of dark pixels, an unfanned region of dark pixels each (i) comprising a vertical channel for transferring charge and (ii) shielded from incident light,
electrically and directly connected to and positioned below the unfanned region of dark pixels, a horizontal CCD (HCCD), and
electrically connected to the HCCD, an output structure for conversion of charge to voltage,
wherein (i) a width of the dark pixels in the fanned region decreases along a direction extending from the array of active pixels to the unfanned region, and (ii) a width of the dark pixels in the unfanned region is substantially constant along a direction extending from the fanned region to the HCCD.
2. The image sensor of claim 1 , wherein one or more dark pixels in the fanned region comprises a PSR.
3. The image sensor of claim 1 , wherein one or more dark pixels in the unfanned region comprises a PSR.
4. The image sensor of claim 1 , wherein a width of the vertical channel within dark pixels of the fanned region is substantially equal to a width of the vertical channel within dark pixels of the unfanned region.
5. The image sensor of claim 1 , wherein one or more dark pixels in the fanned region lack a PSR.
6. The image sensor of claim 1 , wherein one or more dark pixels in the unfanned region lack a PSR.
7. The image sensor of claim 1 , wherein one or more of the sub-arrays comprises:
a region of active pixels each comprising (i) a PSR and (ii) a vertical channel for transferring charge from the PSR;
electrically connected to the region of active pixels, an unfanned region of dark pixels each (i) comprising a vertical channel for transferring charge and (ii) shielded from incident light;
electrically connected to the unfanned region of dark pixels, an HCCD; and
electrically connected to the HCCD, an output structure for conversion of charge to voltage,
wherein a width of the dark pixels in the unfanned region is substantially equal to a width of the active pixels in the region of active pixels.
8. The image sensor of claim 1 , wherein the output structure of one sub-array is disposed within a gap between two sub-arrays resulting from a pixel-width decrease within a fanned region of dark pixels within at least one of the two sub-arrays.
9. The image sensor of claim 1 , wherein the output structures of two adjoining sub-arrays are both disposed within a gap between the two sub-arrays resulting from a pixel-width decrease within a fanned region of dark pixels within at least one of the two sub-arrays.
10. The image sensor of claim 1 , wherein the output structure of at least one of the sub-arrays comprises (i) a dummy shift register having a width substantially equal to a width of shift registers in the HCCD, (ii) a charge-carrying region having a width, along at least a portion of its length, smaller than the width of shift registers in the HCCD, (iii) a sense node, and (iv) an amplifier for conversion of charge into a voltage signal.
11. The image sensor of claim 10 , wherein the charge-carrying region comprises a tapered region having a width that decreases along at least a portion of its length.
12. The image sensor of claim 1 , further comprising a plurality of control gate electrodes extending across fanned regions of dark pixels of at least two sub-arrays.
13. The image sensor of claim 1 , wherein a direction of charge transfer in the vertical channels of the active pixels is (i) substantially parallel to a direction of charge transfer in the vertical channels of the dark pixels of the unfanned region and (ii) substantially perpendicular to a direction of charge transfer in the HCCD.
14. The image sensor of claim 1 , wherein the HCCD comprises a plurality of shift registers having substantially equal dimensions in a direction of charge transfer within the HCCD.