Time-of-flight arrangement and method for a time-of-flight measurement

Patent metadata

Field	Value
Publication number	US-12019190-B2
Application number	US-201916963329-A
Country	US
Kind code	B2
Filing date	Jan 30, 2019
Priority date	Jan 31, 2018
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

A time-of-flight arrangement (10) comprises a laser (15), a laser driver (12), a clock generator (11) that is coupled to the laser (15) via the laser driver (12), a photodiode circuit (50) and a time-to-digital converter (14). The photodiode circuit (50) comprises an avalanche photodiode (51), a quenching circuit (52), a diode node (53) and a readout circuit (54). The quenching circuit (52) is coupled via the diode node (53) to the avalanche photodiode (51). An input of the readout circuit (54) is connected to the diode node (53). At least one of the clock generator (11) and the readout circuit (54) is coupled on its output side to the input side of the time-to-digital converter (14).

First claim

The invention claimed is:

1. A time-of-flight arrangement comprising:
a laser;
a laser driver;
a clock generator that is coupled to the laser via the laser driver;
a photodiode circuit comprising an avalanche photodiode, a quenching circuit, a diode node and a readout circuit, wherein the quenching circuit is coupled via the diode node to the avalanche photodiode and an input of the readout circuit is connected to the diode node; and

a time-to-digital converter,
wherein at least one of the clock generator and the readout circuit is coupled on its output side to the input side of the time-to-digital converter,
wherein the time-of-flight arrangement is configured to operate in a calibration phase and in a measurement phase, wherein a delay information is determined in the calibration phase,
wherein in the measurement phase, a parameter of a circuit of the time-of-flight arrangement is set as a function of the delay information or a measurement result is shifted as a function of the delay information,
wherein the readout circuit comprises a readout buffer having an input coupled to the diode node and a sense buffer having an input connected to the diode node,
wherein an output of the sense buffer is coupled to an input side of the time-to-digital converter and the sense buffer is configured to generate a trigger sense signal in a pulse form,
wherein the readout buffer is configured to generate a readout signal in the form of a pulse,
wherein the time-of-flight arrangement comprises a readout logic, and
wherein an output of the readout buffer is coupled to an input of the readout logic and an output of the readout logic is coupled to the input side of the time-to-digital converter.

2. The time-of-flight arrangement according to claim 1 ,
wherein the time-to-digital converter comprises a ring oscillator, a counter, a first and a second latch, an evaluation block and a histogram block,
wherein the ring oscillator comprises a plurality of inverting elements,
wherein the counter is connected on its input side to an output of one of the plurality of inverting elements,
wherein the first and the second latch are connected on its input side to the ring oscillator and the counter and on its output side via the evaluation block to the histogram block, and
wherein a control input of the first latch is connected to a start input of the time-to-digital converter and a control input of the second latch is connected to a first stop input of the time-to-digital converter.

3. The time-of-flight arrangement according to claim 2 ,
comprising a readout logic, wherein an output of the sense buffer is coupled to the start input of the time-to-digital converter and an output of the readout buffer is coupled to the first stop input of the time-to-digital converter via the readout logic.

4. The time-of-flight arrangement according to claim 2 ,
comprising a readout logic, wherein an output of the sense buffer is coupled to the first stop input of the time-to-digital converter and an output of the readout buffer is coupled to a second stop input of the time-to-digital converter via the readout logic.

5. The time-of-flight arrangement according to claim 2 ,
wherein the time-to-digital converter comprises a third latch that is connected on its input side to the ring oscillator and to the counter and on its output side via the evaluation block to the histogram block, and
wherein a control input of the third latch is connected to a second stop input of the time-to-digital converter.

6. The time-of-flight arrangement according to claim 1 ,
wherein the photodiode circuit comprises an enable switch, a supply terminal and a trigger input, wherein the clock generator is coupled on its output side to the trigger input, the trigger input is connected to a control terminal of the enable switch and the enable switch couples the supply terminal to the diode node.

7. The time-of-flight arrangement according to claim 1 ,
wherein the photodiode circuit comprises a trigger input and the readout circuit comprises a readout gate having a first input coupled via the trigger input to the clock generator and a second input coupled to the diode node.

8. The time-of-flight arrangement according to claim 1 ,
wherein an output of the clock generator is coupled to a start input of the time-to-digital converter.

9. The time-of-flight arrangement according to claim 1 ,
further comprising a current sensor coupled to the laser, wherein an output of the current sensor is coupled to an input side of the time-to-digital converter.

10. The time-of-flight arrangement according to claim 9 ,
further comprising an electrical calibration path which comprises the laser driver, the current sensor and the photodiode circuit and couples the clock generator to the input side of the time-to-digital converter.

11. The time-of-flight arrangement according to claim 1 ,
further comprising an adjustable delay circuit having an input coupled to an output of the clock generator and having an output coupled to the input side of the time-to-digital converter at least in the measurement phase, wherein the delay generated by the adjustable delay circuit is set as a function of the delay information in the measurement phase.

12. The time-of-flight arrangement according to claim 1 ,
further comprising:
a further oscillator coupled to the time-to-digital converter that comprises a ring oscillator;
a first and a second memory; and
an evaluation circuit coupled to the time-to-digital converter and the first and the second memory.

13. A method for a time-of-flight measurement, the method comprising:
operating a time-of-flight arrangement in both a calibration phase and a measurement phase, wherein the time-of-flight arrangement comprises:
a laser;
a laser driver;
a clock generator that is coupled to the laser via the laser driver;
a photodiode circuit comprising an avalanche photodiode, a quenching circuit, a diode node and a readout circuit, wherein the quenching circuit is coupled via the diode node to the avalanche photodiode and an input of the readout circuit is connected to the diode node; and
a time-to-digital converter, wherein at least one of the clock generator and the readout circuit is coupled on its output side to the input side of the time-to-digital converter; determining a delay information in the calibration phase, and

setting a parameter of a circuit of the time-of-flight arrangement as a function of the delay information or shifting a measurement result as a function of the delay information in the measurement phase,
wherein the readout circuit comprises a readout buffer having an input coupled to the diode node and a sense buffer having an input connected to the diode node,
wherein the time-to-digital converter comprises a ring oscillator, a counter, a first and a second latch, an evaluation block and a histogram block,
wherein the ring oscillator comprises a plurality of inverting elements,
wherein the counter is connected on its input side to an output of one of the plurality of inverting elements,
wherein the first and the second latch are connected on its input side to the ring oscillator and the counter and on its output side via the evaluation block to the histogram block, and
wherein a control input of the first latch is connected to a start input of the time-to-digital converter and a control input of the second latch is connected to a first stop input of the time-to-digital converter.

14. A time-of-flight arrangement comprising:
a laser;
a laser driver;
a clock generator that is coupled to the laser via the laser driver;

Assignees

• Ams Ag

Inventors

• Kappel Robert
• Mautner Christian

Classifications

• G01S7/497

  Means for monitoring or calibrating · CPC title

• G01S7/484

  Transmitters · CPC title

• G01S17/894

  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 · CPC title

• G01S17/18

  wherein range gates are used · CPC title

• G01S17/14

  wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters · CPC title