Hybrid imaging sensor with shared readout
A pixel circuit includes a pixel array and a color filter. The pixel array includes a plurality of pixels arranged in rows and columns, each pixel including four photodiodes, a floating diffusion, and four transfer transistors. The color filter array includes a plurality of color filters each having one of a plurality of colors and disposed over at least one of the pixels. Each of the plurality of pixels is coupled to a first readout circuit, and the plurality of pixels includes (i) a first subset of the pixels not coupled to a second readout circuit and (ii) a second subset of the pixels coupled to the second readout circuit. Floating diffusions of two diagonally arranged pixels are coupled together, and the two diagonally arranged pixels coupled together are disposed underneath color filters of a same color.
1 . A pixel circuit, comprising:
a pixel array including a plurality of pixels arranged in rows and columns, wherein each pixel of the plurality of pixels includes:
a plurality of photodiodes configured to photogenerate image charge in response to incident light;
a floating diffusion coupled to receive the image charge from the plurality of photodiodes; and
a plurality of transfer transistors coupled between corresponding ones of the photodiodes and the floating diffusion to transfer the image charges from the respective photodiodes to the floating diffusion; and
a color filter array disposed over the pixel array, wherein the color filter array includes a plurality of color filters each having one of a plurality of colors and disposed over at least one of the pixels,
wherein—
the plurality of pixels includes a first subset of the pixels coupled to a first readout circuit but not coupled to a second readout circuit, and a second subset of the pixels selectively coupled to the second readout circuit,
floating diffusions of two adjacent and diagonally arranged pixels of the plurality of pixels are coupled together, and
the two adjacent and diagonally arranged pixels coupled together are disposed underneath color filters of a same color.
2 . The pixel circuit of claim 1 , wherein:
a floating diffusion of a first pixel in row N and column N is coupled to a floating diffusion of a second pixel in row N+1 and column N+1, and
a floating diffusion of a third pixel in row N and column N+1 is coupled to a floating diffusion of a fourth pixel in row N+1 and column N.
3 . The pixel circuit of claim 1 , wherein the color filter array comprises a quad color filter array such that in each 2×2 grouping of pixels—
color filters of a same color are disposed over a first pair of pixels diagonally arranged and included in the first subset of the pixels, wherein the floating diffusions of the pixels of the first pair are coupled together, and
clear filters are disposed over a second pair of pixels diagonally arranged and included in the second subset, wherein the floating diffusions of the pixels of the second pair are coupled together.
4 . The pixel circuit of claim 1 , wherein the color filter array comprises a quad Bayer filter array such that color filters of a same color are disposed over a 2×2 grouping of pixels, and wherein each 2×2 grouping of pixels includes a first pair of diagonally arranged pixels whose floating diffusions are coupled together and a second pair of diagonally arranged pixels whose floating diffusions are coupled together.
5 . The pixel circuit of claim 1 , wherein in each pair of adjacent rows—
a floating diffusion of a first pixel in row N and column N is coupled to a floating diffusion of a second pixel in row N+1 and column N+1, and
a floating diffusion of a third pixel in row N and column N+1 is coupled to a floating diffusion of a fourth pixel in row N+1 and column N+2.
6 . The pixel circuit of claim 1 , wherein the color filter array comprises a quad color filter array such that in each pair of adjacent rows—
color filters of a same color are disposed over a first pair of pixels diagonally arranged and included in the first subset of the pixels, wherein the floating diffusions of the pixels of the first pair are coupled together, and
clear filters are disposed over a second pair of pixels diagonally arranged and included in the second subset, wherein the floating diffusions of the pixels of the second pair are coupled together,
wherein a first pixel of the first pair of pixels and a first pixel of the second pair of pixels are arranged in a same column, and
wherein a second pixel of the first pair of pixels and a second pixel of the second pair of pixels are arranged in different, non-adjacent columns.
7 . The pixel circuit of claim 1 , wherein the color filter array comprises a zigzag quad Bayer filter array such that color filters of a same color are disposed over four pixels arranged in two adjacent rows and three adjacent columns, and wherein the four pixels include a first pair of diagonally arranged pixels whose floating diffusions are coupled together and a second pair of diagonally arranged pixels whose floating diffusions are coupled together.
8 . The pixel circuit of claim 1 , wherein the two diagonally arranged pixels coupled together are included in a same one of the first subset of the pixels or the second subset of the pixels.
9 . The pixel circuit of claim 1 , wherein the pixels included in the second subset of the pixels are arranged in a checkerboard pattern.
10 . The pixel circuit of claim 1 , wherein the second subset of the pixels comprises 50% of the pixels included in the pixel array.
11 . An imaging system, comprising:
a pixel circuit including:
a pixel array having a plurality of pixels arranged in rows and columns, wherein each pixel includes:
a plurality of photodiodes configured to photogenerate image charge in response to incident light;
a floating diffusion coupled to receive the image charge from the plurality of photodiodes; and
a plurality of transfer transistors coupled between corresponding ones of the photodiodes and the floating diffusion to transfer the image charges from the respective photodiodes to the floating diffusion; and
a color filter array disposed over the pixel array, wherein the color filter array includes a plurality of color filters each having one of a plurality of colors and disposed over at least one of the pixels;
a first readout circuit;
a second readout circuit, wherein the plurality of pixels includes a first subset of the pixels coupled to the first readout circuit but not coupled to the second readout circuit, and a second subset of the pixels selectivity coupled to the second readout circuit, wherein the second readout circuit is coupled to each of the pixels included in the second subset to read out a second set of data signals; and
a mode select switch circuit coupled to the pixels included in the second subset of the pixels, wherein the pixels included in the second subset of the pixels are configured to provide either the first set of data signals to the first readout circuit or the second set of data signals to the second readout circuit in response to the mode select circuit,
wherein floating diffusions of two adjacent and diagonally arranged pixels are coupled together, and
wherein the two adjacent and diagonally arranged pixels coupled together are disposed underneath color filters of a same color.
12 . The imaging system of claim 11 , wherein:
a floating diffusion of a first pixel in row N and column N is coupled to a floating diffusion of a second pixel in row N+1 and column N+1, and
a floating diffusion of a third pixel in row N and column N+1 is coupled to a floating diffusion of a fourth pixel in row N+1 and column N.
13 . The imaging system of claim 11 , wherein the color filter array comprises a quad color filter array including red color filters, blue color filters, green color filters, and clear filters such that in each 2×2 grouping of pixels—
color filters of a same color are disposed over a first pair of pixels diagonally arranged and included in the first subset of the pixels, wherein the floating diffusions of the pixels of the first pair are coupled together, and
clear filters are disposed over a second pair of pixels diagonally arranged and included in the second subset of the pixels, wherein the floating diffusions of the pixels of the second pair are coupled together.
14 . The imaging system of claim 11 , wherein the color filter array comprises a quad Bayer filter array such that color filters of a same color are disposed over a 2×2 grouping of pixels, and wherein each 2×2 grouping of pixels includes a first pair of diagonally arranged pixels whose floating diffusions are coupled together and a second pair of diagonally arranged pixels whose floating diffusions are coupled together.
15 . The imaging system of claim 11 , wherein in each pair of adjacent rows—
a floating diffusion of a first pixel in row N and column N is coupled to a floating diffusion of a second pixel in row N+1 and column N+1, and
a floating diffusion of a third pixel in row N and column N+1 is coupled to a floating diffusion of a fourth pixel in row N+1 and column N+2.
16 . The imaging system of claim 11 , wherein the color filter array comprises a quad color filter array including red color filters, blue color filters, green color filters, and clear filters such that in each pair of adjacent rows—
red color filters, blue color filters, and green color filters of a same color are disposed over a first pair of pixels diagonally arranged and included in the first subset of the pixels, wherein the floating diffusions of the pixels of the first pair are coupled together, and
clear filters are disposed over a second pair of pixels diagonally arranged and included in the second subset, wherein the floating diffusions of the pixels of the second pair are coupled together,
wherein a first pixel of the first pair of pixels and a first pixel of the second pair of pixels are arranged in a same column, and
wherein a second pixel of the first pair of pixels and a second pixel of the second pair of pixels are arranged in different, non-adjacent columns.
17 . The imaging system of claim 11 , wherein the color filter array comprises a zigzag quad Bayer filter array such that color filters of a same color are disposed over four pixels arranged in two adjacent rows and three adjacent columns, and wherein the four pixels include a first pair of diagonally arranged pixels whose floating diffusions are coupled together and a second pair of diagonally arranged pixels whose floating diffusions are coupled together.
18 . The imaging system of claim 11 , wherein the two diagonally arranged pixels coupled together are included in a same one of the first subset or the second subset.
19 . The imaging system of claim 11 , wherein the pixels included in the second subset of the pixels are arranged in a checkerboard pattern.
20 . The imaging system of claim 11 , wherein the second subset of the pixels comprises 50% of the pixels included in the pixel array.