Image sensor for removing horizontal noise

1. An image sensor, comprising:

a pixel array including a plurality of unit pixels located at every row or column;

an analog bus located at every row or column for transferring output signals of the pixel array; and

a readout circuit for reading the output signals of the pixel array loaded on the analog bus,

wherein the readout circuit includes:

a plurality of first transistors having a drain connected to the column analog bus and a source connected to a supply voltage; and

a second transistor having a drain connected to a gate of the second transistor and gates of the first transistors, and a source connected to the supply voltage,

wherein a size of the second transistor is larger than a size of each of the first transistors, and a current amount flowing through the second transistor is larger than a current amount flowing through the first transistors.

2. The image sensor as recited in claim 1 , wherein the first transistors are located at every row and the second transistor forms current mirrors with the first transistors.

3. The image sensor as recited in claim 1 , wherein the first transistors are located at every column and the second transistor forms current mirrors with the first transistors.

4. The image sensor as recited in claim 1 , wherein the first transistors and the second transistor are NMOS transistor.

5. The image sensor as recited in claim 1 , wherein the supply voltage is a ground voltage.