Patent ID: 8153947
Filing Date: 2012-04-10
Classification: H01L,H04N

Abstract:
1. An image sensor comprising an array of pixels, each pixel comprising: a photodiode coupled between a first reference voltage and a first switch, said first switch operable to connect said photodiode to a first node; a capacitor arranged to store a charge accumulated by said photodiode, said capacitor being coupled between a second reference voltage and a second node; a second switch coupled between said first and second nodes, said second switch being operable to connect said capacitor to said first node; and read circuitry connected to said first node for reading the voltage at said second node, the image sensor further comprising control circuitry arranged to control said first and second switches in each pixel to transfer a charge accumulated by said photodiode to said capacitor at the end of an integration period of said image sensor, and to control, in a row of pixels, the second switch to connect said capacitor to said first node when said row of pixels is to be read, wherein said photodiode is formed in a first P-type well and said second switch comprises a first transistor formed in a second P-type well, said first and second P-type wells having different doping levels, and wherein an N+ type region formed at a junction of said first and second P-type wells serves as said first node.