Active pixel sensor with intra-pixel charge transfer
DCFirst Claim
1. An imaging device including a monolithic semiconductor integrated circuit substrate, said imaging device comprising a focal plane array of pixel cells, each of said cells comprising:
- a photoreceptor, adjacent said substrate, to control accumulating photo-generated charge a readout circuit comprising at least a buffering transistor and a selecting transistor, formed in said substrate;
a coupling section formed on said substrate adjacent said photoreceptor, having a sensing node connected to said output transistor and at least one coupling stage for transferring said photogenerated charge to said sensing node; and
wherein said transistors in said readout circuit are formed of an integrated circuit technology which is compatible with complimentary metal oxide semiconductor (CMOS) technology, formed on said substrate, said substrate being of a first conductivity type, said readout circuit comprising transistors of a first conductivity type, a well region of a second conductivity type in said substrate and plural semiconductor transistors of a second conductivity type formed in said well region.
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Abstract
An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node.
113 Citations
19 Claims
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1. An imaging device including a monolithic semiconductor integrated circuit substrate, said imaging device comprising a focal plane array of pixel cells, each of said cells comprising:
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a photoreceptor, adjacent said substrate, to control accumulating photo-generated charge a readout circuit comprising at least a buffering transistor and a selecting transistor, formed in said substrate;
a coupling section formed on said substrate adjacent said photoreceptor, having a sensing node connected to said output transistor and at least one coupling stage for transferring said photogenerated charge to said sensing node; and
wherein said transistors in said readout circuit are formed of an integrated circuit technology which is compatible with complimentary metal oxide semiconductor (CMOS) technology, formed on said substrate, said substrate being of a first conductivity type, said readout circuit comprising transistors of a first conductivity type, a well region of a second conductivity type in said substrate and plural semiconductor transistors of a second conductivity type formed in said well region. - View Dependent Claims (2)
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3. An imaging device comprising a focal plane array of pixel cells, each of said pixel cells including a monolithic semiconductor integrated circuit substrate, each of said pixel cells comprising:
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a photoreceptor overlying a first portion of said substrate and operating to accumulate photo-generated charge in the first portion of said substrate that underlies said photogate;
a charge transfer section, formed in said substrate adjacent said photogate, having a sensing node adjacent said photoreceptor and at least one charge coupling stage, operating to transfer charge from said first portion of said substrate to said sensing node; and
a readout circuit connected to said sensing node and to no other sensing node of any other one of said pixel cells, so that said readout circuit of each said one of said pixel cells is associated with only one photoreceptor and only one charge transfer section, said readout circuit including at least a buffering transistor and a selection transistor. - View Dependent Claims (4, 5, 6, 7, 8)
said sensing node of said charge transfer section stage comprises a floating node; and
said charge coupling stage comprises a transfer gate between said floating node and said photogate.
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5. The imaging device of claim 4 wherein said floating node is one of:
- (a) a floating diffusion, and (b) a floating gate.
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6. An imaging device as in claim 3, wherein said readout circuit includes a sampling element which stores the charge received from said substrate, and a shorting element which shorts across the sampling element after the charge is read.
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7. A device as in claim 6, wherein said sampling element is a capacitor and said shorting element is a shorting FET.
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8. An imaging device as in claim 3, wherein said readout circuit is formed of an integrated circuit technology which is compatible with complimentary metal oxide semiconductor (CMOS) technology.
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9. An imaging device, comprising:
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a substrate of a type which can store optical charge therein, said substrate formed of a plurality of pixel cells, each pixel cell comprising;
an optical charge storage section, including a photoreceptor;
a charge transfer section, having a sensing node, and having a first state in which charge from the photoreceptor is isolated from the sensing node and a second state in which charge from the photoreceptor is coupled to said sensing node; and
a readout circuit, having an input connected to said sensing node, said readout circuit connected to no other nodes of any of the other pixel cells of the device so that each optical charge storage section and charge transfer section is associated with only one readout circuit. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An imaging device, comprising:
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a focal plane array of pixel cells, including a substrate of a type which can store optical charge therein;
each pixel cell formed in a predetermined area of said substrate, and comprising;
an optical charge storage section, including a photoreceptor overlying a first portion of said predetermined area of said substrate which accumulates charge therein;
a plurality of circuitry elements, formed in a second portion of said predetermined area; and
a microlens, overlying at least said second portion, and directing light impinging on said second portion to said first portion. - View Dependent Claims (18)
a charge transfer section, having a sensing node, and having a first state in which charge in the substrate is isolated from the sensing node and a second state in which charge in the substrate is coupled to said sensing node; and
a readout circuit, having an input connected to said sensing node, said readout circuit connected to no other nodes of any of the other pixel cells of the device so that each optical charge storage section and charge transfer section is associated with only one readout circuit.
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19. An imaging device including a monolithic semiconductor integrated circuit substrate, said imaging device comprising a focal plane array of pixel cells, each one of said cells comprising:
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a photosensor coupled to said substrate, and accumulating photo-generated charge in said substrate;
a readout circuit comprising at least a select transistor and a buffering transistor, formed in said substrate;
a coupling section, formed on said substrate adjacent said photgate, having a sensing node connected to said output transistor and at least one coupling stage which transfers charge from said underlying portion of said substrate to said sensing node.
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Specification