US6021172A — Active pixel sensor having intra-pixel charge tra…

Claim 1

Independent Claim 185 words

An imaging device including a monolithic semiconductor integrated circuit substrate, said imaging device comprising a focal plane array of pixel cells in said substrate, each of said cells comprising: a photogate overlying said substrate for accumulating photo-generated charge in an underlying portion of said substrate; a readout circuit comprising at least an output transistor formed in said substrate; a charge coupled device section formed on said substrate adjacent said photogate having a sensing node connected to said output transistor and at least one charge coupled device stage for transferring charge from said underlying portion of said substrate to said sensing node; and said imaging device further comprising an analog-to-digital converter formed in said substrate and connected to said readout circuit; and wherein said readout circuit is a metal oxide semiconductor circuit formed on said substrate, said substrate being of a first conductivity type, said MOS circuit comprising plural metal oxide field effect transistors of a first conductivity type, a well region of a second conductivity type in said substrate and plural metal oxide semiconductor transistors of a second conductivity type formed in said well region.

Claim 2

Dependent Claim 185 words

An imaging device including a monolithic semiconductor integrated circuit substrate, said imaging device comprising a focal plane array of pixel cells in said substrate, each of said cells comprising: a photogate overlying said substrate for accumulating photo-generated charge in an underlying portion of said substrate; a readout circuit comprising at least an output transistor formed in said substrate; a charge coupled device section formed on said substrate adjacent said photogate having a sensing node connected to said output transistor and at least one charge coupled device stage for transferring charge from said underlying portion of said substrate to said sensing node; and said imaging device further comprising an analog-to-digital converter formed in said substrate and connected to said readout circuit; and wherein said readout circuit is a metal oxide semiconductor circuit formed on said substrate, said substrate being of a first conductivity type, said MOS circuit comprising plural metal oxide field effect transistors of a first conductivity type, a well region of a second conductivity type in said substrate and plural metal oxide semiconductor transistors of a second conductivity type formed in said well region.

Claim 3

Dependent Claim 37 words

The imaging device of claim 1 wherein: said sensing node of said charge coupled device stage comprises a floating node; and said charge coupled device stage comprises a transfer gate between said floating node and said photogate.

Claim 4

Dependent Claim 22 words

The imaging device of claim 2 wherein said floating node is one of: (a) a floating diffusion, and (b) a floating gate.

Claim 5

Dependent Claim 38 words

The imaging device of claim 2 further comprising: a drain diffusion connected to a drain bias voltage; and a reset gate between said floating node and said drain diffusion, said reset gate connected to a reset control signal.

Claim 6

Dependent Claim 30 words

The imaging device of claim 4 wherein said output transistor comprises a field effect source follower transistor, said floating node being connected to a gate of said source follower transistor.

Claim 7

Dependent Claim 101 words

The imaging device of claim 4 wherein said readout circuit further comprises a double correlated sampling circuit comprising: a pair of sample and hold field effect transistors formed in said substrates, each sample and hold field effect transistor having one of a source and drain thereof connected to a source of said source follower transistor; a pair of sample and hold capacitors connected to the other one of the source and drain of a respective one of said pair of sample and hold transistors; and means for sensing a potential of each of said sample and hold capacitors at respective intervals.

Claim 8

Dependent Claim 24 words

The imaging device of claim 6 further comprising means for sensing a difference between the potentials of said pair of sample and hold capacitors.

Claim 9

Dependent Claim 33 words

The imaging device of claim 6 further comprising means for shorting across each of said pair of sample and hold capacitors simultaneously while said means for sensing measures a fixed pattern noise difference.

Claim 10

Dependent Claim 152 words

The imaging device of claim 6 wherein said focal plane array of cells is organized by rows and columns of said cells, and wherein said means for sensing at period intervals comprises: a row select field effect transistor formed in said substrate having its source and drain connected between said source of said source follower transistor and said pair of sample and hold transistors and a gate connected to a row select signal; a pair of sample and hold output transistors having respective gates and sources connected across respective ones of said pair of sample and hold capacitors, and having respective drains; respective differential output nodes of said correlated double sampling circuit; a pair of column select transistors formed in said substrate each having a source and drain connected between a drain of a respective one of said sample and hold output transistors and a gate connected to a column select signal.

Claim 11

Dependent Claim 54 words

The imaging device of claim 9 wherein each of said transistors is a metal oxide field effect transistor, said source follower transistor, said row select transistor and said pair sample and hold transistors being n-channel devices, said pair of sample and hold output transistors and said pair of column select transistors being p-channel devices.

Claim 12

Dependent Claim 51 words

The imaging device of claim 9 wherein said analog-to-digital converter is connected to the readout circuits of all cells in a given one of said column, said imaging device comprising an analog-to-digital converter for each one of said column connected to the readout circuits of the cells in the respective column.

Claim 13

Dependent Claim 32 words

The imaging device of claim 11 wherein said analog-to-digital converter comprises one of: (a) a sigma delta modulation circuit, (b) a single slope analog-to-digital converter, (c) an analog-to-digital converter employing successive approximations.

Claim 14

Dependent Claim 22 words

The imaging device of claim 1 further comprising means for periodically resetting a potential of said sensing node to a predetermined potential.

Claim 15

Dependent Claim 26 words

The imaging device of claim 1 wherein said readout circuit further comprises a double correlated sampling circuit having an input node connected to said output transistor.

Claim 16

Dependent Claim 54 words

The imaging device of claim 1 further comprising a micro-lens layer overlying said substrate, said micro-lens layer comprising: a refractive layer; individual lenses formed in said layer in registration with individual ones of said cells, each of said individual lenses having a curvature for focusing light toward a center portion of the respective cell.

Claim 17

Dependent Claim 15 words

The imaging device of claim 15 wherein said refractive layer comprises an oxide of silicon.

Claim 18

Dependent Claim 12 words

The imaging device of claim 16 wherein said refractive layer comprises polyimide.

Claim 19

Dependent Claim 33 words

The imaging device of claim 15 wherein each of said individual lenses covers portions of the corresponding cell including said photogate as well as said charge coupled device stage and said readout circuit.

Claim 20

Dependent Claim 32 words

The imaging device of claim 1 wherein said analog-to-digital converter comprises one of: (a) a sigma delta modulation circuit, b) a single slope analog-to-digital converter, (c) an analog-to-digital converter employing successive approximations.

Claim 21

Dependent Claim 242 words

An imaging device comprising: a monolithic semiconductor integrated circuit substrate; a focal plane array of pixel cells formed on said integrated circuit substrate, each of said pixel cells comprising: a photogate overlying said substrate, accumulating photo-generated charge in an underlying portion of said substrate; a charge transfer section, receiving the accumulated photo-generated charge from the photogate; and a coupling section, formed on said substrate adjacent said charge transfer section, having a sensing node connected to said photogate through said charge transfer section, wherein said charge transfer section transfers stored charge from said photogate to said sensing node; and said focal plane array including a plurality of units, each unit of said focal plane array including at least one of said pixel cells, and further comprising: a readout controller which controls readout of said pixel cells to read out all pixel cells of each unit in parallel; and at least two analog to digital converters, formed in said substrate, and each connected to one pixel cell of said unit to read out information from said pixel cells of said unit in parallel, wherein said units are rows, said focal plane array is arranged into a plurality of rows and columns, one A/D converter being associated with each column of said array so that said columns of pixel cells are connected to respective A/D converters in parallel relative to one another and an entire row of pixel cells is simultaneously read and A/D converted.

Claim 22

Dependent Claim 242 words

An imaging device comprising: a monolithic semiconductor integrated circuit substrate; a focal plane array of pixel cells formed on said integrated circuit substrate, each of said pixel cells comprising: a photogate overlying said substrate, accumulating photo-generated charge in an underlying portion of said substrate; a charge transfer section, receiving the accumulated photo-generated charge from the photogate; and a coupling section, formed on said substrate adjacent said charge transfer section, having a sensing node connected to said photogate through said charge transfer section, wherein said charge transfer section transfers stored charge from said photogate to said sensing node; and said focal plane array including a plurality of units, each unit of said focal plane array including at least one of said pixel cells, and further comprising: a readout controller which controls readout of said pixel cells to read out all pixel cells of each unit in parallel; and at least two analog to digital converters, formed in said substrate, and each connected to one pixel cell of said unit to read out information from said pixel cells of said unit in parallel, wherein said units are rows, said focal plane array is arranged into a plurality of rows and columns, one A/D converter being associated with each column of said array so that said columns of pixel cells are connected to respective A/D converters in parallel relative to one another and an entire row of pixel cells is simultaneously read and A/D converted.

Claim 23

Independent Claim 262 words

A device for imaging capturing and processing, comprising: (1) a focal plane array of pixel cells, each of said pixel cells including a monolithic semiconductor integrated circuit substrate, wherein each of said pixel cells includes: (a) a photogate overlying a first portion of said substrate and operating to accumulate photo-generated charge in a first portion of said substrate that underlies said photogate; and (b) a charge transfer section, formed in said substrate adjacent said photogate, having a sensing node adjacent said photogate and at least one charge coupling stage, operating to transfer charge from said first portion of said substrate to said sensing node; (2) an A/D converter, formed on said integrated circuit substrate and connected to said sensing node of at least one of said pixel cells, but less than all of said pixel cells, so that less than all of said pixel cells are attached to said A/D converter, wherein said A/D converter includes: (a) a signal path portion, having an input receiving said signal and an output coupling said signal; (b) a reference path, selectively providing a full scale signal; (c) a signal-combining element, receiving said signal on said signal path and said signal on said reference path, and outputting a value indicative of a combination signal thereof; (d) an integrating element, connected to receive and integrate said combination signal; (e) a comparing element connected to an output of said integrating element, comparing said combination signal with a reference and producing an output indicative thereof; and (f) a latch element which counts a ratio of values of said output.

Claim 24

Independent Claim 262 words

A device for imaging capturing and processing, comprising: (1) a focal plane array of pixel cells, each of said pixel cells including a monolithic semiconductor integrated circuit substrate, wherein each of said pixel cells includes: (a) a photogate overlying a first portion of said substrate and operating to accumulate photo-generated charge in a first portion of said substrate that underlies said photogate; and (b) a charge transfer section, formed in said substrate adjacent said photogate, having a sensing node adjacent said photogate and at least one charge coupling stage, operating to transfer charge from said first portion of said substrate to said sensing node; (2) an A/D converter, formed on said integrated circuit substrate and connected to said sensing node of at least one of said pixel cells, but less than all of said pixel cells, so that less than all of said pixel cells are attached to said A/D converter, wherein said A/D converter includes: (a) a signal path portion, having an input receiving said signal and an output coupling said signal; (b) a reference path, selectively providing a full scale signal; (c) a signal-combining element, receiving said signal on said signal path and said signal on said reference path, and outputting a value indicative of a combination signal thereof; (d) an integrating element, connected to receive and integrate said combination signal; (e) a comparing element connected to an output of said integrating element, comparing said combination signal with a reference and producing an output indicative thereof; and (f) a latch element which counts a ratio of values of said output.

Claim 25

Dependent Claim 64 words

A device as in claim 21 wherein said latch element produces a binary signal indicative of a result of the comparison; and said reference path of said signal-combining element comprises a first branch which adds the full scale signal when the result of the comparison is a first amount, and a second branch which adds another signal when the result is a second amount.

Claim 26

Dependent Claim 23 words

A device as in claim 22 wherein said first branch adds the full scale signal and second branch subtracts a full scale signal.

Claim 27

Dependent Claim 14 words

A device as in claim 21 wherein said integrator element includes a capacitor therein.

Claim 28

Dependent Claim 13 words

A device as in claim 24 wherein said capacitor is an MOS capacitor.

Claim 29

Dependent Claim 30 words

A device as in claim 24 further comprising a reset switch across the capacitor, said reset switch resetting a value of the integrator at the beginning of each pixel conversation.

Claim 30

Dependent Claim 14 words

A device as in claim 26 wherein said reset switch is an MOS transistor.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2003-01-31	2003-08-02	2004-02-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2007-01-31	2007-08-02	2008-02-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2011-01-31	2011-08-02	2012-02-01	$7700.00	Window Closed / Lapsed

Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

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