Imaging systems with single-photon avalanche diodes and ambient light level detection

Patent metadata

Field	Value
Publication number	US-2021223398-A1
Application number	US-202016948269-A
Country	US
Kind code	A1
Filing date	Sep 10, 2020
Priority date	Jan 21, 2020
Publication date	Jul 22, 2021
Grant date	—

Abstract

A light detection and ranging (LIDAR) imaging system may include a semiconductor device based on single-photon avalanche diodes (SPADs). The LIDAR imaging system may also include a light source configured to emit light such that the semiconductor device is exposed to both ambient light and a reflected version of the laser light. Ambient light level detection circuitry may be included to determine a brightness of the ambient light based on an output signal from the semiconductor device. The ambient light level detection circuitry may include a plurality of comparators that receive different reference signals and are coupled to respective counters. The results from the counters may be used to determine the brightness of the ambient light in the scene. The determined brightness may then be used to discriminate between the ambient light and the reflected version of the light.

First claim

What is claimed is:

1 . A system, comprising:
a semiconductor device that includes a single-photon avalanche diode; signal processing circuitry configured to receive an output signal from the semiconductor device; and ambient light level detection circuitry configured to receive the output signal from the semiconductor device and determine an ambient light level based on the output signal.

2 . The system defined in claim 1 , wherein the ambient light level detection circuitry comprises a plurality of comparators and a plurality of counters and wherein each counter is coupled to a corresponding comparator.

3 . The system defined in claim 2 , wherein each one of the plurality of comparators is configured to receive the output signal at a respective first input terminal and a respective reference signal at a respective second input terminal.

4 . The system defined in claim 3 , wherein the respective reference signal at each second input terminal has a unique magnitude.

5 . The system defined in claim 3 , wherein each one of the plurality of comparators is a voltage comparator and wherein the respective reference signal at each second input terminal has a unique voltage magnitude.

6 . The system defined in claim 3 , wherein each one of the plurality of comparators is a current comparator and wherein the respective reference signal at each second input terminal has a unique current magnitude.

7 . The system defined in claim 2 , wherein each one of the plurality of comparators has respective first and second input terminals.

8 . The system defined in claim 7 , wherein each one of the first input terminals receives the output signal.

9 . The system defined in claim 8 , wherein the ambient light level detection circuitry comprises reference signal generation circuitry that is configured to provide reference signals having unique magnitudes to each second input terminal.

10 . The system defined in claim 2 , wherein the ambient light level detection circuitry comprises a controller that is configured to determine the ambient light level based on the counts at each one of the plurality of counters.

11 . The system defined in claim 1 , further comprising:
a laser configured to emit light, wherein the semiconductor device is configured to receive a reflected version of the light from the laser and wherein the signal processing circuitry is configured to use the ambient light level detected by the ambient light level detection circuitry to discriminate between output signals caused by ambient light and output signals caused by the reflected version of the light from the laser.

12 . A system operable with a light source that is configured to emit light, the system comprising:
a semiconductor device that includes a single-photon avalanche diode, wherein the semiconductor device is exposed to both ambient light and a reflected version of the light; ambient light level detection circuitry configured to determine a brightness of the ambient light based on an output signal from the semiconductor device; and processing circuitry configured to discriminate between the ambient light and the reflected version of the light based on the brightness determined by the ambient light level detection circuitry.

13 . The system defined in claim 12 , wherein the ambient light level detection circuitry comprises a plurality of comparators that receive progressively decreasing reference signals.

14 . The system defined in claim 13 , wherein the ambient light level detection circuitry further comprises a plurality of counters and wherein each counter is configured to count a number of times the output signal exceeds the respective reference signal for a respective comparator.

15 . The system defined in claim 14 , wherein the ambient light level detection circuitry is configured to determine the brightness of the ambient light based on the number counted by each counter after an ambient light tracking cycle is complete.

16 . The system defined in claim 12 , wherein the ambient light level detection circuitry comprises a plurality of voltage comparators that receive reference signals having progressively decreasing voltages.

17 . The system defined in claim 12 , wherein the ambient light level detection circuitry comprises a plurality of current comparators that receive reference signals having progressively decreasing currents.

18 . A light detection and ranging (LIDAR) imaging system comprising:
a silicon photomultiplier; a plurality of comparators having respective first and second inputs, wherein each first input is configured to receive an output signal from the silicon photomultiplier; reference signal generating circuitry configured to provide different reference signals to each one of the second inputs; and a plurality of counters each configured to count a number of times the output signal exceeds the respective reference signal for a respective comparator.

19 . The LIDAR imaging system defined in claim 18 , further comprising:
a receiver configured to receive the output signal from the silicon photomultiplier; and LIDAR processing circuitry coupled to the receiver and the plurality of counters.

20 . The LIDAR imaging system defined in claim 18 , wherein the different reference signals each have a magnitude that differs by one photon level from magnitudes of adjacent reference signals.

Assignees

• Semiconductor Components Ind Llc

Inventors

• Koudar Ivan
• Ledvina Jan

Classifications

• G01S7/4863

  Detector arrays, e.g. charge-transfer gates · CPC title

• G01J1/4204

  with determination of ambient light (solar light G01J2001/4266) · CPC title

• G01J2001/4453

  PMT · CPC title

• G01S17/89 Primary

  for mapping or imaging · CPC title

• G01S7/4914

  of detector arrays, e.g. charge-transfer gates · CPC title