Dual conversion gain imagers
First Claim
Patent Images
1. An imager device, comprising:
- a diffusion region, connected to receive stored charge from a photosensitive device; and
a circuit connected to said diffusion region, said circuit providing said diffusion region with at least a dual conversion gain switchable between first and second conversion gains.
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Abstract
An imager with dual conversion gain floating diffusion regions. The dual conversion gain regions yield (1) high conversion gain and sensitivity to achieve excellent low light performance and (2) high full well capacity and conversion gain to achieve high dynamic range. A dual conversion gain element is coupled between each floating diffusion node and a respective capacitor. The dual conversion gain element switches in the capacitance of the capacitor to change the conversion gain of the floating diffusion node from a first conversion gain to a second conversion gain. The imager may be a CMOS or CCD type imager.
155 Citations
126 Claims
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1. An imager device, comprising:
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a diffusion region, connected to receive stored charge from a photosensitive device; and
a circuit connected to said diffusion region, said circuit providing said diffusion region with at least a dual conversion gain switchable between first and second conversion gains. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A CMOS imager pixel, comprising:
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a photosensor for accumulating stored charge;
a diffusion region, connected to receive the charge from the photosensor, said diffusion region having a first conversion gain; and
a conversion gain altering circuit connected to said diffusion region, said conversion gain altering circuit being controlled to change the first conversion gain to the second conversion gain and to change the second conversion gain to the first conversion gain. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A CMOS imager pixel, comprising:
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a photosensor for accumulating stored charge;
a first transistor being controlled to reset said pixel;
a second transistor being controlled to transfer the stored charge from the photosensor;
a diffusion region, connected to receive the charge from said second transistor, said diffusion region having a first conversion gain;
a capacitive element; and
a third transistor coupled between said diffusion region and said capacitive element, said third transistor being controlled to connect said capacitive element to said diffusion region such that said diffusion region obtains at least a second conversion gain. - View Dependent Claims (37, 38, 39)
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40. A CMOS imager pixel, comprising:
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a photosensor for accumulating stored charge;
a first transistor being controlled to reset said pixel;
a second transistor being controlled to transfer the stored charge from the photosensor;
a diffusion region, connected to receive the charge from said second transistor, said diffusion region having a first conversion gain;
a third transistor; and
a capacitive element coupled between said diffusion region and said third transistor, said third transistor being controlled to connect said capacitive element to said diffusion region such that said diffusion region obtains at least a second conversion gain. - View Dependent Claims (41, 42, 43)
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44. A CMOS imager pixel, comprising:
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a photosensor for accumulating stored charge;
a first transistor being controlled to reset said pixel;
a diffusion region, connected to receive the charge from said photosensor, said diffusion region having a first conversion gain;
a capacitive element; and
a second transistor coupled between said diffusion region and said capacitive element, said second transistor being controlled to connect said capacitive element to said diffusion region such that said diffusion region obtains a second conversion gain. - View Dependent Claims (45, 46, 47)
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48. A CMOS imager pixel, comprising:
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a photosensor for accumulating stored charge;
a first transistor being controlled to reset said pixel;
a diffusion region, connected to receive the charge from said photosensor, said diffusion region having a first conversion gain;
a second transistor; and
a capacitive element coupled between said diffusion region and said second transistor, said second transistor being controlled to connect said capacitive element to said diffusion region such that said diffusion region obtains a second conversion gain. - View Dependent Claims (49, 50, 51)
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52. A CCD imager comprising:
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a register for inputting and outputting photo-generated charge;
a diffusion region, connected to receive the photo-generated charge from said register, said diffusion region having a first conversion gain; and
a conversion gain altering circuit connected to said diffusion region, said conversion gain altering circuit being controlled to change the first conversion gain to the second conversion gain and to change the second conversion gain to the first conversion gain. - View Dependent Claims (53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65)
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66. An imager system, comprising:
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a processor; and
an imaging device electrically coupled to said processor, said imaging device comprising a pixel array, at least one pixel of said array comprising;
a photosensor for accumulating stored charge, a diffusion region, connected to receive the charge from the photosensor, said diffusion region having a first conversion gain, and a conversion gain altering circuit connected to said diffusion region, said conversion gain altering circuit being controlled to change the first conversion gain to the second conversion gain and to change the second conversion gain to the first conversion gain. - View Dependent Claims (67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88)
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89. An imager system, comprising:
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a processor; and
an imaging device electrically coupled to said processor, said imaging device comprising;
a diffusion region, connected to receive stored charge from a photosensitive device; and
a circuit connected to said diffusion region, said circuit providing said diffusion region with multiple conversion gains.
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90. An imager system, comprising:
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a processor; and
an imaging device electrically coupled to said processor, said imaging device comprising;
a register for inputting and outputting photo-generated charge;
a diffusion region, connected to receive the photo-generated charge from said register, said diffusion region having a first conversion gain, and a conversion gain altering circuit connected to said diffusion region, said conversion gain altering circuit being controlled to change the first conversion gain to one of multiple conversion gains and to change said one of multiple conversion gains to said first conversion gain.
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91. A method of operating an imager device, said method comprising:
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storing photo-generated charge in a diffusion region;
outputting a first signal representing the stored photo-generated charge;
changing a conversion gain of the diffusion region; and
outputting a second signal representing the stored photo-generated charge in the diffusion region having the changed conversion gain. - View Dependent Claims (92, 93, 94, 95, 96, 97, 98, 99, 100)
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101. A method of operating an imager device, said method comprising:
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transferring photo-generated charge to a diffusion region;
determining an amount of the stored charge;
comparing the amount to a predetermined threshold;
changing a conversion gain of the diffusion region if it is determined that the amount of stored charge exceeds the threshold; and
outputting a signal indicative of the charge in the floating diffusion region. - View Dependent Claims (102, 103, 104, 105, 106, 107, 108, 109, 110)
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111. A method of operating a CMOS imager device, said method comprising:
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providing a photosensor having a first capacitance;
providing a diffusion region having a second capacitance that is less than the first capacitance;
storing photo-generated charge from the photosensor in the diffusion region;
determining an amount of the stored charge;
comparing the amount to a predetermined threshold; and
adding a third capacitance to the diffusion region such that the combination of the second and third capacitances is greater than the first capacitance if it is determined that the amount of stored charge exceeds the threshold. - View Dependent Claims (112, 113, 114, 115, 116, 117, 118, 119)
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120. A method of fabricating a dual conversion gain pixel, said method comprising the steps of:
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providing a substrate;
providing a photosensitive region within the substrate;
providing a floating diffusion region within said substrate, the floating diffusion region having a first capacitance; and
providing a conversion gain altering circuit within the substrate, wherein the conversion gain altering circuit is controllable to add a second capacitance to the capacitance of the diffusion region. - View Dependent Claims (121, 122, 123, 124)
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125. A method of fabricating a dual conversion gain pixel, said method comprising the steps of:
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providing a substrate;
providing a photosensitive region within the substrate;
forming a first transistor within the substrate for resetting the pixel;
providing a floating diffusion region within said substrate, the floating diffusion region having a first capacitance;
providing a second transistor between the photosensitive region and the floating diffusion region, the second transistor being controllable to transfer charge from tie photosensitive region to the floating diffusion region;
forming a capacitive element within the substrate; and
forming a third transistor within the substrate, wherein the third transistor is connected between the diffusion region and the capacitive element such that when the third transistor is activated, a capacitance of the capacitive element is added to the first capacitance.
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126. A method of fabricating a dual conversion gain pixel, said method comprising the steps of:
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providing a substrate;
providing a photosensitive region within the substrate;
forming a first transistor within the substrate for resetting the pixel;
providing a floating diffusion region within said substrate, the floating diffusion region having a first capacitance and being connected to the photosensitive region;
forming a capacitive element within the substrate; and
forming a second transistor within the substrate, wherein the second transistor is connected between the diffusion region and the capacitive element such that when the second transistor is activated, a capacitance of the capacitive element is added to the first capacitance.
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Specification