Sense amplifier for high-density imaging array
First Claim
1. A sense amplifier comprising:
- an input node;
an output node;
an input transistor having a gate connected to the input node, a source connected to a first supply voltage rail, and a drain;
a cascode transistor having a gate connected to a cascode node, a source connected to the drain of the input transistor, and a drain connected to the output node; and
a load transistor having a gate connected to a bias node, a drain connected to the output node, and a source connected to a second supply voltage rail;
wherein the w/l ratio of the input transistor and the cascode transistor is much greater than the w/l ratio of the load transistor.
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Accused Products
Abstract
A sense amplifier comprises an input node and an output node. An input transistor has a gate connected to the input node, a source connected to a first supply voltage rail, and a drain. A cascode transistor has a gate connected to a cascode node, a source connected to the drain of the input transistor, and a drain connected to the output node. A load transistor has a gate connected to a bias node, a drain connected to the output node, and a source connected to a second supply voltage rail. The gates of the cascode transistor and the load transistor are biased such that the input transistor and the cascode transistor are operated near their threshold and the load transistor is operated above threshold. In a presently preferred embodiment of the present invention, the input transistor and the cascode transistor of the sense amplifier are wide and short, such that they operate in below threshold, whereas the load transistor is made long and relatively narrow, so that it operates above threshold.
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Citations
24 Claims
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1. A sense amplifier comprising:
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an input node; an output node; an input transistor having a gate connected to the input node, a source connected to a first supply voltage rail, and a drain; a cascode transistor having a gate connected to a cascode node, a source connected to the drain of the input transistor, and a drain connected to the output node; and a load transistor having a gate connected to a bias node, a drain connected to the output node, and a source connected to a second supply voltage rail; wherein the w/l ratio of the input transistor and the cascode transistor is much greater than the w/l ratio of the load transistor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sense amplifier for use in a photosensing array including a plurality of photosensing elements arranged in an array of rows and columns, each column having a column width, the sense amplifier comprising:
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an input node; an output node; an input transistor having a gate connected to the input node, a source connected to a first supply voltage rail, and a drain; a cascode transistor having a gate connected to a cascode node, a source connected to the drain of the input transistor, and a drain connected to the output node; a load transistor having a gate connected to a bias node, a drain connected to the output node, and a source connected to a second supply voltage rail; wherein the w/l ratio of the input transistor and the cascode transistor is much greater than the w/l ratio of the load transistor; and wherein said sense amplifier may be disposed in an area on an integrated circuit, said area having a width no greater than the column width. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A sense amplifier comprising:
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an input node; an output node; an input transistor of a first conductivity type having a gate connected to the input node, a source connected to a first supply voltage rail, and a drain; a cascode transistor of said first conductivity type having a gate connected to a cascode node, a source connected to the drain of the input transistor, and a drain connected to the output node; and a load transistor of a second conductivity type opposite that of said first conductivity type having a gate connected to a bias node, a drain connected to the output node, and a source connected to a second supply voltage rail; wherein the w/l ratio of the input transistor and the cascode transistor is much greater than the w/l ratio of the load transistor. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A sense amplifier for use in a photosensing array including a plurality of single-transistor photosensing elements arranged in an array of rows and columns, each column having a column width, the sense amplifier comprising:
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an input node; an output node; an input transistor of a first conductivity type having a gate connected to the input node, a source connected to a first supply voltage rail, and a drain; a cascode transistor of said first conductivity type having a gate connected to a cascode node, a source connected to the drain of the input transistor, and a drain connected to the output node; a load transistor of a second conductivity type opposite that of said first conductivity type having a gate connected to a bias node, a drain connected to the output node, and a source connected to a second supply voltage rail; wherein the w/l ratio of the input transistor and the cascode transistor is much greater than the w/l ratio of the load transistor; and wherein said sense amplifier may be disposed in an area on an integrated circuit, said area having a width no greater than the column width. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification