Pixel cell with high storage capacitance for a CMOS imager
First Claim
Patent Images
1. An optical sensing circuit comprising:
- a first capacitive structure, the first capacitive structure being adapted to receive a plurality of photons and responsively produce a respective plurality of electric charges;
a second capacitive structure, the second capacitive structure being adapted to control an electrical current, the second capacitive structure comprising a conductive layer having an area of from about 0.3 μ
m2 to about 25 μ
m2; and
an electrically conductive path, the electrically conductive path being coupled between the first capacitive structure and the second capacitive structure.
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Abstract
A pixel sensor cell for use in a CMOS imager exhibiting improved storage capacitance. The source follower transistor is formed with a large gate that has an area from about 0.3 μm2 to about 10 μm2. The large size of the source follower gate enables the photocharge collector area to be kept small, thereby permitting use of the pixel cell in dense arrays, and maintaining low leakage levels. Methods for forming the source follower transistor and pixel cell are also disclosed.
36 Citations
9 Claims
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1. An optical sensing circuit comprising:
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a first capacitive structure, the first capacitive structure being adapted to receive a plurality of photons and responsively produce a respective plurality of electric charges;
a second capacitive structure, the second capacitive structure being adapted to control an electrical current, the second capacitive structure comprising a conductive layer having an area of from about 0.3 μ
m2 to about 25 μ
m2; and
an electrically conductive path, the electrically conductive path being coupled between the first capacitive structure and the second capacitive structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification