High dynamic range cascaded integration pixel cell
First Claim
Patent Images
1. An imager pixel cell comprising:
- a photo-conversion device for generating electrical charges in response to photon energy impinging thereon;
a first capacitor associated with the photo-conversion device;
a first transistor electrically coupled to the photo-conversion device for resetting the device to a particular voltage;
a second transistor coupled to the photo-conversion device for coupling a second capacitor for accumulating charge converted by the photo-conversion device when the converted charge exceeds a first threshold value during the integration period;
a source follower transistor having a gate for receiving the electrical charges; and
a row select transistor for coupling the output of the source follower transistor to an output line.
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Abstract
A cascaded imaging storage system for a pixel is disclosed for improving intrascene dynamic range. Charges accumulated in a first capacitor spill over into a second capacitor when a charge storage capacity of the first capacitor is exceeded. A third capacitor may also be provided such that charges accumulated by said second capacitor spill over into the third capacitor when the charge storage capacity of the second capacitor is exceeded.
10 Citations
49 Claims
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1. An imager pixel cell comprising:
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a photo-conversion device for generating electrical charges in response to photon energy impinging thereon; a first capacitor associated with the photo-conversion device; a first transistor electrically coupled to the photo-conversion device for resetting the device to a particular voltage; a second transistor coupled to the photo-conversion device for coupling a second capacitor for accumulating charge converted by the photo-conversion device when the converted charge exceeds a first threshold value during the integration period; a source follower transistor having a gate for receiving the electrical charges; and a row select transistor for coupling the output of the source follower transistor to an output line. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An imager pixel cell comprising:
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a photo-conversion device for generating electrical charges in response to photon energy impinging thereon; a first reset transistor for resetting the photo-conversion device to a predetermined voltage during a reset period; a storage system for storing the electrical charges, the storage system comprising a sequence of capacitors arranged such that a later capacitor in a sequence stores charge which overflows from an earlier capacitor in the sequence during an integration period; a source follower transistor having a gate for receiving the electrical charges; and a row select transistor for coupling the output of the source follower transistor to an output line. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An imager pixel cell comprising:
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a semiconductor substrate; a photo-conversion device supported by the substrate, the photo-conversion device having a charge conversion node; a first capacitor having one terminal connected to the charge conversion node; a first transistor formed on the substrate for resetting the charge conversion node to a predetermined voltage; a second transistor formed on the substrate; a second capacitor having one terminal connected to the charge conversion node through the second transistor; a source follower transistor having a gate for receiving the electrical charges; and a row select transistor for coupling the output of the source follower transistor to an output line. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. method for operating an imager, the method comprising:
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generating charge from incident light; storing a first portion of the charge in a first capacitor; storing a second portion of the charge in a second capacitor when the charge exceeds a limit; and reading out the first and second portions. - View Dependent Claims (42)
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43. method for operating an imager, the method comprising:
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generating charge from incident light; storing the charge in a sequence of capacitors selectively coupled by a sequence of transistors; turning on the transistors in sequence such that a later capacitor in the sequence of capacitors stores charge that overflows from an earlier capacitor in the sequence of capacitors; and reading out charge stored in the sequence of capacitors.
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44. A method for increasing the dynamic range of an imager, the method comprising:
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converting incident light to an electric charge during an integration period; storing a first portion of the electric charge in a first storage node; storing a second portion of the electric charge in a second storage node, wherein the second portion comprises a portion of the electric charge above a first limit; storing a third portion of the electric charge in a third storage node, wherein the third portion comprises a portion of the electric charge above a second limit; reading out the first, second, and third portions during a readout period. - View Dependent Claims (45, 46)
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47. A method for operating an imager, the method comprising:
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converting incident light into an electric charge; accumulating a first portion of the electric charge in a first capacitor; turning on a first transistor coupled between the first capacitor and a second capacitor when the electric charge exceeds the storage capacity of the first capacitor; accumulating a second portion of the electric charge in the second capacitor; and reading out charge stored in the first and second capacitors. - View Dependent Claims (48, 49)
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Specification