# US 7,466,255 B1 · Multiplexed-input-separated Σ-Δ analog-to-digital converter for pixel-level analog-to-digital conversion utilizing a feedback DAC separation

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- Number: US 7,466,255 B1
- Document ID: US7466255B1
- Status: Granted
- Kind: B1
- Application number: 11/600,914
- Filed: 2006-11-17
- Granted: 2008-12-16
- Earliest claimed: 2005-11-17
- Assignees: University of Rochester
- Inventors: Zeljko Ignjatovic; Mark F. Bocko
- Web page: https://patentgrep.com/patent/US7466255B1

## CPC

- H10F 39/803: {Pixels having integrated switching, control, storage or amplification elements}
- H03M 3/474: {using time-division multiplexing}
- H04N 25/00: Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N 25/78: Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters
- H03M 3/33: {the dither being a random signal}
- H03M 3/456: {the modulator having a first order loop filter in the feedforward path}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

In an array of imaging elements, a pixel level analog-to-digital-converter design splits the quantizer into an input transistor at the pixel location and a quantizer body for each row. The feedback digital-to-analog converter is also split into two components, one at the pixel location and one provided either for each row or for the entire array.

## Claims

### Claim 1

A multiplexed input-separated ΣΔ analog-to-digital converter for an array of photodetectors, each of the photodetectors in the array functioning as an integrator, the converter comprising a quantizer, the quantizer being separated into:
an input transistor at a pixel defined by each of the photodetectors; and
a quantizer body for each row of the pixels, the quantizer body connected to the input transistors in the row.

### Claim 2 (depends on 1)

The converter of claim 1, further comprising a feedback loop between the quantizer body and each of the pixels in the row.

### Claim 3 (depends on 2)

The converter of claim 2, wherein the feedback loop comprises a digital-to-analog converter.

### Claim 4 (depends on 3)

The converter of claim 3, wherein the digital-to-analog converter comprises a first component and a second component, and wherein the first component is provided for each of the photodetectors at a corresponding one of the pixels.

### Claim 5 (depends on 4)

The converter of claim 4, wherein the second component is provided for each of the rows.

### Claim 6 (depends on 5)

The converter of claim 5, wherein a connection from the input transistor to the quantizer body is on a separate bus from the feedback loop.

### Claim 7 (depends on 6)

The converter of claim 6, wherein the feedback loop comprises a switch.

### Claim 8 (depends on 7)

The converter of claim 7, wherein the switch operates under control of an output of the quantizer body.

### Claim 9 (depends on 4)

The converter of claim 4, wherein a single second component is provided for an entirety of the array.

### Claim 10 (depends on 9)

The converter of claim 9, wherein a connection from the input transistor to the quantizer body is on a separate bus from the feedback loop.

### Claim 11 (depends on 10)

The converter of claim 10, wherein the feedback loop comprises a switch.

### Claim 12 (depends on 11)

The converter of claim 11, wherein the switch operates under control of an output of the quantizer body.

### Claim 13

A multiplexed input-separated ΣΔ analog-to-digital converter for an array of photodetectors, each of the photodetectors in the array functioning as an integrator, the converter comprising:
an input transistor at a pixel defined by each of the photodetectors;
a quantizer body for each row of the pixels, the quantizer body connected to the input transistors in the row; and
a feedback loop between the quantizer body and each of the pixels in the row;
wherein the feedback loop comprises a digital-to-analog converter;
wherein the digital-to-analog converter comprises a first component and a second component, and wherein the first component is provided for each of the photodetectors at a corresponding one of the pixels;
wherein the second component is provided for each of the rows; and
wherein a connection from the input transistor to the quantizer body is on a common bus with the feedback loop.

### Claim 14 (depends on 13)

The converter of claim 13, wherein the common bus comprises a switch for connecting the common bus in alternation with the quantizer body and the feedback loop.

### Claim 15

A multiplexed input-separated ΣΔ analog-to-digital converter for an array of photodetectors, each of the photodetectors in the array functioning as an integrator, the converter comprising:
an input transistor at a pixel defined by each of the photodetectors;
a quantizer body for each row of the pixels, the quantizer body connected to the input transistors in the row; and
a feedback loop between the quantizer body and each of the pixels in the row;
wherein the feedback loop comprises a digital-to-analog converter;
wherein the digital-to-analog converter comprises a first component and a second component, and wherein the first component is provided for each of the photodetectors at a corresponding one of the pixels;
wherein a single second component is provided for an entirety of the array; and
wherein a connection from the input transistor to the quantizer body is on a common bus with the feedback loop.

### Claim 16 (depends on 15)

The converter of claim 15, wherein the common bus comprises a switch for connecting the common bus in alternation with the quantizer body and the feedback loop.

### Claim 17 (depends on 16)

The converter of claim 16, wherein the feedback loop comprises a switch.

### Claim 18 (depends on 17)

The converter of claim 17, wherein the switch in the feedback loop operates under control of an output of the quantizer body.

### Claim 19

A multiplexed input-separated ΣΔ analog-to-digital converter for an array of photodetectors, each of the photodetectors in the array functioning as an integrator, the converter comprising:
an input transistor at a pixel defined by each of the photodetectors;
a quantizer body for each row of the pixels, the quantizer body connected to the input transistors in the row; and
a feedback loop between the quantizer body and each of the pixels in the row;
wherein a connection from the input transistor to the quantizer body is on a common bus with the feedback loop.