One-Transistor Pixel Array with Cascoded Column Circuit
First Claim
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1. A device comprising:
- an array of pixels, at least some pixels in the array of pixels comprising;
a chemically-sensitive field-effect transistor (chemFET) including a source terminal and a drain terminal, and a floating gate coupled to a passivation layer; and
a cascode transistor including a source terminal, a drain terminal and a gate terminal, wherein the source terminal of the cascode transistor is directly connected to the drain terminal of the chemFET; and
a plurality of column lines and a plurality of row lines coupled to pixels in the array of pixels, wherein each column line in the plurality of column lines is directly connected to drain terminals of cascode transistors of a corresponding first plurality of pixels in the array, and wherein each row line in the plurality of row lines is directly connected to the source terminals of chemFETs of a corresponding second plurality of pixels in the array; and
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Abstract
To reduce the pixel size to the smallest dimensions and simplest form of operation, a pixel may be formed by using only one ion sensitive field-effect transistor (ISFET). This one-transistor, or 1T, pixel can provide gain by converting the drain current to voltage in the column. Configurable pixels can be created to allow both common source read out as well as source follower read out. A plurality of the 1T pixels may form an array, having a number of rows and a number of columns and a column readout circuit in each column. A cascoded device enabled during readout may be used to provide increased programmable gain.
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18 Claims
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1. A device comprising:
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an array of pixels, at least some pixels in the array of pixels comprising; a chemically-sensitive field-effect transistor (chemFET) including a source terminal and a drain terminal, and a floating gate coupled to a passivation layer; and a cascode transistor including a source terminal, a drain terminal and a gate terminal, wherein the source terminal of the cascode transistor is directly connected to the drain terminal of the chemFET; and a plurality of column lines and a plurality of row lines coupled to pixels in the array of pixels, wherein each column line in the plurality of column lines is directly connected to drain terminals of cascode transistors of a corresponding first plurality of pixels in the array, and wherein each row line in the plurality of row lines is directly connected to the source terminals of chemFETs of a corresponding second plurality of pixels in the array; and - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A device comprising:
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an array of chemically-sensitive field-effect transistors (chemFETs), at least some chemFETs in the array of chemFETs including a source terminal and a drain terminal, and a floating gate coupled to a passivation layer; a plurality of column lines and a plurality of row lines coupled to chemFETs in the array of chemFETs, wherein each column line in the plurality of column lines is directly connected to drain terminals of a corresponding plurality of chemFETs in the array, and each row line in the plurality of row lines is directly connected to source terminals of a corresponding second plurality of chemFETs in the array; and respective cascode transistors coupled to corresponding column lines in the plurality of column lines, wherein a given cascode transistor includes a source terminal, a drain terminal and a gate terminal, and the source terminal of the given cascode transistor is coupled to the corresponding column line. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification