Patent ID: 6667767
Filing Date: 2003-12-23
Classification: H01L,H04N

Abstract:
An image sensor comprising:a coupling capacitor to which a photoelectric conversion voltage generated when a pixel is exposed to light and a photoelectric conversion voltage generated when said pixel is unexposed to light are sequentially applied; and a source follower through which an output, generated at a node on the output side of said coupling capacitor, being the remainder of said photoelectric conversion voltage generated when said pixel is unexposed to light and that generated when said pixel is exposed to light is taken; whereby said node on the output side of said capacitor is clamped on a sum of a definite voltage and a threshold voltage of a transistor constituting said source follower and, after said photoelectric conversion voltage generated when said pixel is exposed to light has been read out, said photoelectric conversion voltage generated when said pixel is unexposed to light is read out.