# US 2018/0026058 A1 · Circuit and method for controlling a spad array

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- Number: US 2018/0026058 A1
- Document ID: US20180026058A1
- Status: Published application
- Kind: A1
- Application number: 15/709,791
- Filed: 2017-09-20
- Published: 2018-01-25
- Earliest claimed: 2015-03-23
- Assignees: STMicroelectronics (Grenoble 2) SAS; STMicroelectronics (Research & Development) Limited
- Applicants: STMicroelectronics (Grenoble 2) SAS; STMicroelectronics (Research & Development) Limited
- Inventors: Pascal Mellot; Stuart McLeod; Bruce Rae; Marc Drader
- Web page: https://patentgrep.com/patent/US20180026058A1

## CPC

- H10F 39/103: {the at least one element covered by H10F30/00 having potential barriers, e.g. integrated devices comprising photodiodes or phototransistors}
- 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 7/497: Means for monitoring or calibrating
- H04N 25/773: comprising photon counting circuits, e.g. single photon detection [SPD] or single photon avalanche diodes [SPAD]
- H10F 30/225: the potential barrier working in avalanche mode, e.g. avalanche photodiodes
- H10F 39/107: {having multiple elements covered by H10F30/00 in a repetitive configuration, e.g. radiation detectors comprising photodiode arrays}
- H10F 39/1515: {Optical shielding}
- H10F 39/8057: {Optical shielding}
- H10F 77/334: {for shielding light, e.g. light blocking layers or cold shields for infrared detectors}
- 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

A circuit may include an array of single photon avalanche diode (SPAD) cells, each SPAD cell configured to be selectively enabled by an activation signal. The circuit may include a control circuit configured to selectively enable a subset of the array of SPAD cells based on a measured count rate of the array of SPAD cells.

## Claims

### Claim 1

A circuit comprising:
a plurality of photodiode cells, each photodiode cell having an enable input and an output;
a first circuit having a plurality of inputs, each input of the first circuit coupled to the respective output of each photodiode cell of the plurality of photodiode cells; and
a controller having an input coupled to the output of the first circuit and a plurality of outputs, each output of the controller coupled to the respective enable input of each photodiode cell of the plurality of photodiode cells, the controller configured to selectively enable a subset of the plurality of photodiode cells based on the output of the first circuit.

### Claim 2 (depends on 1)

The circuit of claim 1, wherein each photodiode cell comprises an avalanche diode.

### Claim 3 (depends on 2)

The circuit of claim 2, wherein the first circuit comprises an OR gate.

### Claim 4 (depends on 2)

The circuit of claim 2, wherein each photodiode cell comprises a first, second, third and fourth transistors, the first transistor coupled between a ground terminal and an anode of the avalanche diode, the anode of the avalanche diode further coupled to a first supply terminal via the second transistor and to a gate of the third transistor, the third transistor coupled to the output of the photodiode cell via the fourth transistor.

### Claim 5 (depends on 4)

The circuit of claim 4, wherein the enable input of each photodiode cell of the plurality of photodiode cells is coupled to a gate of the respective fourth transistor and to a gate of the respective first transistor via a respective first inverter in series with a respective second inverter, wherein the first inverter is coupled to the first supply terminal and the second inverter is coupled to a second supply terminal.

### Claim 6

A method comprising:
receiving outputs of each single photon avalanche diode (SPAD) cell of a plurality of SPAD cells;
generating an output signal based on the received outputs of each SPAD cell; and
selectively enabling a subset of the plurality of SPAD cells based on the generated output signal, wherein a first SPAD cell of the plurality of SPAD has lower sensitivity than a second SPAD cell of the plurality of SPAD cells.

### Claim 7 (depends on 6)

The method of claim 6, further comprising permanently disabling faulty SPAD cells of the plurality of SPAD cells.

### Claim 8 (depends on 6)

The method of claim 6, further comprising:
determining an ambient count rate count based on the generated output signal when a light source are is disabled; and
determining a peak count rate based on the generated output signal when optical pulses are produced by the light source.

### Claim 9 (depends on 8)

The method of claim 8, wherein selectively enabling the subset of the plurality of SPAD cells is based on the ambient count rate and on the peak count rate.

### Claim 10

A single photon avalanche diode (SPAD) device comprising:
a light source;
a target array of target SPAD cells, each target SPAD cell having an enable input and an output; and
a first circuit comprising
a second circuit having a plurality of inputs, each input of the first circuit coupled to the respective output of each target SPAD cell, and
a first control circuit having an input coupled to the output of the second circuit and a plurality of outputs, each output of the first control circuit coupled to the respective enable input of each target SPAD cell, the first control circuit configured to selectively enable a subset of the target SPAD cells of the target array of target SPAD cells based on the output of the second circuit.

### Claim 11 (depends on 10)

The SPAD device of claim 10, further comprising:
a reference array of reference SPAD cells, each reference SPAD cell having an enable input and an output;
a third circuit having a plurality of inputs, each input of the third circuit coupled to the respective output of each reference SPAD cell, and
a second control circuit having an input coupled to the output of the third circuit and a plurality of outputs, each output of the second control circuit coupled to the respective enable input of each reference SPAD cell, the second control circuit configured to selectively enable a subset of the reference SPAD cells of the reference array of reference SPAD cells based on the output of the third circuit.

### Claim 12 (depends on 10)

The SPAD device of claim 10, wherein the light source comprises a laser.

### Claim 13 (depends on 10)

The SPAD device of claim 10, wherein the target array has the same size as the reference array.

### Claim 14 (depends on 10)

The SPAD device of claim 10, further comprising a first lens coupled between the light source and an image scene; and a second lens coupled between the image scene and the target array.

### Claim 15

A circuit comprising an array of single photon avalanche diode (SPAD) cells, each SPAD cell of the array of SPAD cells having an enable input and an output, the array of SPAD cells having a first subset of SPAD cells and a second subset of SPAD cells, the second subset of SPAD cells being non-overlapping with the first subset of SPAD cells, wherein each SPAD cell of the first subset of SPAD cells comprises a shield and a photosensitive zone at least partially covered by the shield, the SPAD cells of the first subset of SPAD cells having a lower sensitivity to light than SPAD cells of the second subset of SPAD cells.

### Claim 16 (depends on 15)

The circuit of claim 15, wherein each shield of the SPAD cells of the first subset of SPAD cells cover between 10% and 95% of the respective photosensitive zone.

### Claim 17 (depends on 16)

The circuit of claim 16, wherein each SPAD cell of the first subset of SPAD cells has a sensitivity to light equal to 1/7.5 of the sensitivity to light of a SPAD cell of the second subset of SPAD cells.

### Claim 18 (depends on 16)

The circuit of claim 16, wherein each shield of the SPAD cells of the first subset of SPAD cells has an annular form.

### Claim 19 (depends on 16)

The circuit of claim 16, wherein each shield of the SPAD cells of the first subset of SPAD cells comprises two metal layers separated by an oxide layer.

### Claim 20 (depends on 15)

The circuit of claim 15, further comprising a controller having a plurality of outputs, each output of the controller coupled to the respective enable input of each SPAD cell of the array of SPAD cells, the controller configured to selectively enable a subset of SPAD cells of the array of SPAD cells based on light intensity received by the array of SPAD cells.

### Claim 21 (depends on 20)

The circuit of claim 20, further comprising a first circuit having a plurality of inputs and an output, each input of the first circuit coupled to the respective output of each SPAD cell of the array of SPAD cells, wherein the controller further comprises an input coupled to the output of the first circuit, and the controller is configured to determine the light intensity received by the array of SPAD cells based on the output of the first circuit.