# US 11,444,109 B2 · Global shutter pixel circuit and method for computer vision applications

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- Number: US 11,444,109 B2
- Document ID: US11444109B2
- Status: Granted
- Kind: B2
- Application number: 17/131,346
- Filed: 2020-12-22
- Published: 2021-06-17
- Granted: 2022-09-13
- Earliest claimed: 2017-12-13
- Assignees: Magic Leap, Inc.
- Applicants: Magic Leap, Inc.
- Inventors: Erez Tadmor; David Cohen; Giora Yahav
- Web page: https://patentgrep.com/patent/US11444109B2

## CPC

- H10F 39/8023: {Disposition of the elements in pixels, e.g. smaller elements in the centre of the imager compared to larger elements at the periphery}
- G01S 7/4814: {of transmitters alone}
- G01S 7/4816: {of receivers alone}
- G01S 7/4863: Detector arrays, e.g. charge-transfer gates
- G01S 7/4865: Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487)
- G01S 11/00: Systems for determining distance or velocity not using reflection or reradiation (position-fixing by co-ordinating two or more distance determinations G01S5/00)
- G01S 17/894: Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar
- H04N 23/60: Control of cameras or camera modules
- H04N 23/73: by influencing the exposure time
- H04N 25/77: Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
- H04N 25/771: comprising storage means other than floating diffusion
- H04N 25/778: comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/803: {Pixels having integrated switching, control, storage or amplification elements}
- H10F 39/807: {Pixel isolation structures}
- H10F 39/813: {Electronic components shared by multiple pixels, e.g. one amplifier shared by two pixels}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An image sensor device includes a plurality of pixel cells arranged in a pixel array, a control circuit for controlling an exposure phase and a sampling phase of the image sensor device. Each of the plurality of pixel cells includes a photodiode, a storage diode, and a floating diffusion region. The control circuit is configured to activate the photodiode in a plurality of time windows to sense light reflected from a target as a result of a corresponding plurality of emitted light pulses, with a pre-determined delay time between each time window and a corresponding emitted light pulse. The photodiode can be activated using a plurality of bias voltage pulses or a plurality of global shutter signal pulses.

## Claims

### Claim 1

An image sensor device, comprising:
a plurality of pixel cells arranged in a pixel array;
a control circuit for controlling an exposure phase and a sampling phase of the image sensor device; and
a switching circuit for coupling a pixel power supply line to a first voltage in an exposure phase and to a second voltage in a sampling phase, the first voltage being higher than the second voltage;
wherein each of the plurality of pixel cells comprises:
a photodiode in a semiconductor substrate, a first end of the photodiode coupled to a bias voltage through a shutter gate controlled by a global shutter signal;
a ground contact for coupling a second end of the photodiode to an electrical ground through an electrical ground conductive line;
a storage diode in the semiconductor substrate and coupled to a second end of the photodiode through a first transfer gate controlled by a first transfer signal; and
a floating diffusion region in the semiconductor substrate and coupled to the storage diode through a second transfer gate controlled by a second transfer signal.

### Claim 2 (depends on 1)

The image sensor device of claim 1, wherein the control circuit is configured to activate the photodiode in a plurality of time windows to sense light reflected from a target as a result of a corresponding plurality of emitted light pulses, with a pre-determined delay time between each time window and a corresponding emitted light pulse.

### Claim 3 (depends on 2)

The image sensor device of claim 2, further comprising a drain region, wherein:
a first end of the photodiode is coupled to a bias voltage through the drain region; and
the control circuit is configured to provide a plurality of bias voltage pulses to activate the photodiode in the plurality of time windows to sense reflected light.

### Claim 4 (depends on 2)

The image sensor device of claim 2, wherein the control circuit is configured to provide a plurality of global shutter signal pulses to activate the photodiode in the plurality of time windows to sense reflected light.

### Claim 5

A pixel cell for time-of-flight (ToF) distance measurement, comprising:
a substrate;
a photodiode;
a ground contact for coupling a second end of the photodiode to an electrical ground through an electrical ground conductive line;
a drain region adjacent to the photodiode and coupled to a bias voltage;
a shutter gate disposed between the photodiode and the drain region, the shutter gate controlled by a global shutter signal to apply the bias voltage to bias the photodiode for light sensing;
a storage diode coupled to the photodiode through a first transfer gate controlled by a first transfer signal; and
a floating diffusion region coupled to the storage diode through a second transfer gate controlled by a second transfer signal.

### Claim 6 (depends on 5)

The pixel cell of claim 5, wherein:
the photodiode is formed in a rectangular diffusion area having four side lines;
the shutter gate is disposed along a first side line between the photodiode and the drain region, the shutter gate having a same length as the first side line; and
the first transfer gate is disposed along a second side line adjacent the first side line, the first transfer gate having a length that is half the length of the second side line and disposed over a corner of the photodiode away from the first side line.

### Claim 7 (depends on 5)

The pixel cell of claim 5, further comprising first, second, and third metal interconnect layers, wherein: a first transfer line, a second transfer line, a select line, and a reset line are formed in the first metal interconnect layer along a first direction, and span a total width of W; a voltage supply VDDA line, a voltage supply VSSA line, and a pixel output line are formed in the second metal interconnect layer along a second direction perpendicular to the first direction; and a global shutter line is formed in the third metal interconnect layer along the first 8 direction, the global shutter line having a width substantially equal to W.

### Claim 8 (depends on 5)

The pixel cell of claim 5, wherein the drain region comprises a low capacitance drain diffusion region to facilitate modulating of the bias voltage.