Image sensor that includes sensing pixels sharing a floating diffusion node and operation method thereof

1. An image sensor including a pixel array, wherein the pixel array comprises:

a first unit pixel having first sensing pixels adjacent to each other along a column direction and second sensing pixels adjacent to each other along the column direction, the first sensing pixels being adjacent to the second sensing pixels along a row direction; and

a same color of filter overlapping all of the first and second sensing pixels such that all of the first and second sensing pixels correspond to the same color, wherein:

the first unit pixel has M rows and N columns, where M and N are each integers of 2 or more,

the first unit pixel has N floating diffusion nodes,

the first sensing pixels are arranged in a first column and share a first floating diffusion node among the N floating diffusion nodes,

the second sensing pixels are arranged in a second column and share a second floating diffusion node among the N floating diffusion nodes,

the first floating diffusion node is shared by only the first sensing pixels, and

the second floating diffusion node is shared by only the second sensing pixels.

2. The image sensor as claimed in claim 1 , wherein:

each of the first sensing pixels and the second sensing pixels include a first light sensing device, a second light sensing device, and a third light sensing device, and

photocharges output from the first light sensing device, the second light sensing device, and the third light sensing device are delivered to the first floating diffusion node or the second floating diffusion node at different times.

3. The image sensor as claimed in claim 2 , wherein

the first light sensing device, the second light sensing device, and the third light sensing device have different exposure time periods.

4. The image sensor as claimed in claim 3 , further comprising

a timing controller, wherein

the timing controller transmits,

at a first time point, a signal to turn on a first transmission transistor connected to the first light sensing device,

at a second time point after the first time point, a signal to turn on a second transmission transistor connected to the second light sensing device, and

at a third time point after the second time point, a signal to turn on a third transmission transistor connected to the third light sensing device.

5. The image sensor as claimed in claim 1 , wherein

the first sensing pixels and the second sensing pixels respectively include light sensing devices

sequentially outputting photocharges to the first floating diffusion node and the second floating diffusion node and

sequentially output pixel signals according to orders in which the photocharges are received by the first floating diffusion node and the second floating diffusion node.

6. The image sensor as claimed in claim 5 , further comprising

a read circuit to perform an analog binning operation on the pixel signals that are sequentially output.

7. The image sensor as claimed in claim 1 wherein the pixel array further comprises:

a second unit pixel having third sensing pixels adjacent to each other along the column direction and fourth sensing pixels adjacent to each other along the column direction, the third sensing pixels being adjacent to the fourth sensing pixels along the row direction;

a same color of filter, different from that of the first unit pixel, overlapping all of the third and fourth sensing pixels such that all of the third and fourth sensing pixels correspond to a same color that is different from that of the first unit pixel, wherein:

the first unit pixel includes a first phase detecting pixel,

the second unit pixel includes a second phase detecting pixel, and

a single microlens covers the first and second phase detecting pixels.

8. The image sensor as claimed in claim 7 , wherein:

the first unit pixel includes 3 rows and 3 columns, in which the first sensing pixels, the second sensing pixels, and the first phase detecting pixel are arranged,

the second unit pixel includes 3 rows and 3 columns, in which the third sensing pixels, the fourth sensing pixels, and the second phase detecting pixel are arranged, and

the second phase detecting pixel is directly adjacent to the first phase detecting pixel.

9. The image sensor as claimed in claim 7 , wherein:

the first sensing pixels respectively have different exposure time periods,

the second sensing pixels respectively have different exposure time periods, and

the first and second phase detecting pixels have a same exposure time period.

10. An operation method of an image sensor including a pixel array, the pixel array comprising a plurality of first sensing pixels arranged in a first column and a plurality of second sensing pixels arranged in a second adjacent column, the first sensing pixels sharing a first floating diffusion node and the second sensing pixels sharing a second floating diffusion node, the first floating diffusion node being shared by only the first sensing pixels, and the second floating diffusion node being shared by only the second sensing pixels, the operation method comprising:

sequentially outputting pixel signals by the first sensing pixels through the first floating diffusion node and by the second sensing pixels through the second floating diffusion node;

receiving operation mode information that instructs a general photographing mode or a high dynamic range (HDR) photographing mode;

performing an analog binning operation on the outputted pixel signals when operating in the general photographing mode; and

performing a dynamic range compression (DRC) operation on the outputted pixel signals when the operating in the HDR photographing mode.

11. The operation method as claimed in claim 10 , wherein:

the plurality of sensing pixels includes light sensing devices,

the pixel signals on which the analog binning operation is performed are output from light sensing devices having a same exposure time period, and

the pixel signals on which the DRC operation is performed are output from light sensing devices having different exposure time periods.