Photodetector systems with low-power time-to-digital converter architectures to determine an arrival time of photon at a photodetector based on event detection time window

Patent metadata

Field	Value
Publication number	US-11735681-B2
Application number	US-202217725703-A
Country	US
Kind code	B2
Filing date	Apr 21, 2022
Priority date	Jun 6, 2019
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

An illustrative system may include a component configured to be worn on a body of a user, the component comprising a time-to-digital converter (TDC) configured to: receive, during a predetermined event detection time window that commences in response to an application of a light pulse to a target within the body, a signal triggered by an event in which a photodetector detects a photon of the light pulse after the light pulse reflects from the target; and measure, based on the receiving the signal, a time interval between when the event occurred and an end of the predetermined event detection time window. The system may further include a processor configured to determine, based on the time interval and the predetermined event detection time window, an arrival time of the photon at the photodetector.

First claim

What is claimed is:

1. A system comprising:
a component configured to be worn on a body of a user, the component comprising a time-to-digital converter (TDC) configured to:
receive, during a predetermined event detection time window that commences in response to an application of a light pulse to a target within the body, a signal triggered by an event in which a photodetector detects a photon of the light pulse after the light pulse reflects from the target; and
measure, based on the receiving the signal, a time interval between when the event occurred and an end of the predetermined event detection time window; and

a processor configured to determine, based on the time interval and the predetermined event detection time window, an arrival time of the photon at the photodetector.

2. The system of claim 1 , wherein:
the signal is configured to enable a gated ring oscillator (GRO) of the TDC; and
the measuring is performed using the GRO.

3. The system of claim 2 , wherein the signal is further configured to:
enable the GRO of the TDC while the signal is being received by the TDC; and
disable the GRO of the TDC upon a stopping of the signal.

4. The system of claim 2 , wherein the TDC is further configured to receive, subsequent to the predetermined event detection time window, a second signal configured to disable the GRO of the TDC.

5. The system of claim 4 , wherein the second signal is received upon completion of the predetermined event detection time window.

6. The system of claim 2 , wherein:
the GRO includes one or more pairs of cross-coupled inverters configured to store a state of the GRO when the GRO is disabled; and
the measuring the time interval includes decoding the stored state of the GRO.

7. The system of claim 6 , wherein:
the TDC receives a voltage from a phase-locked loop (PLL) or a delay-locked loop (DLL) that provides an external reference clock; and
at least one of the enabling the GRO and the measuring the time interval is based additionally on the received voltage.

8. The system of claim 1 , wherein:
the TDC is further configured to measure an additional time interval subsequent to the time interval;
the processor is further configured to calibrate the TDC based on the measured additional time interval; and
the determining the arrival time of the photon is further based on the calibrating.

9. The system of claim 8 , wherein the additional time interval is a same or substantially similar length as the predetermined event detection time window.

10. The system of claim 8 , further comprising a calibration circuit configured to provide calculations for the calibrating the TDC.

11. The system of claim 8 , further comprising a lookup table configured to provide calculations for the calibrating the TDC.

12. The system of claim 1 , wherein:
the TDC is further configured to receive an event window signal specifying a starting time of the predetermined event detection time window; and
the determining the arrival time of the photon is further based on the starting time of the predetermined event detection time window.

13. The system of claim 1 , wherein the photodetector comprises:
a single photon avalanche diode (SPAD); and
a fast gating circuit configured to arm and disarm the SPAD.

14. The system of claim 1 , wherein the component is implemented by a non-invasive wearable brain interface system.

15. The system of claim 1 , further comprising a wearable battery configured to provide power to the component.

16. A system comprising:
a time-to-digital converter (TDC) configured to:
receive, during a predetermined event detection time window that commences in response to an application of a light pulse to a target, a signal triggered by an event in which a photodetector detects a photon of the light pulse after the light pulse reflects from the target; and
measure, based on the receiving the signal, a time interval between when the event occurred and an end of the predetermined event detection time window; and

a processor configured to determine, based on the time interval and the predetermined event detection time window, an arrival time of the photon at the photodetector.

17. The system of claim 1 , wherein:
the signal is configured to enable a gated ring oscillator (GRO) of the TDC; and
the measuring is performed using the GRO.

18. The system of claim 17 , wherein the signal is further configured to:
enable the GRO of the TDC while the signal is being received by the TDC; and
disable the GRO of the TDC upon a stopping of the signal.

19. The system of claim 17 , wherein the TDC is further configured to receive, subsequent to the predetermined event detection time window, a second signal configured to disable the GRO of the TDC.

20. A method comprising:
receiving, by a time-to-digital converter (TDC), during a predetermined event detection time window that commences in response to an application of a light pulse to a target, a signal triggered by an event in which a photodetector detects a photon of the light pulse after the light pulse reflects from the target;
measuring, by the TDC based on the receiving the signal, a time interval between when the event occurred and an end of the predetermined event detection time window; and
determining, based on the time interval and the predetermined event detection time window, an arrival time of the photon at the photodetector.

Assignees

• Hi Llc

Inventors

• Sorgenfrei Sebastian
• Dahle Jacob
• Field Ryan
• Do Valle Bruno
• Jin Rong

Classifications

• H10F77/959

  for devices working in avalanche mode · CPC title

• H10F30/225 Primary

  the potential barrier working in avalanche mode, e.g. avalanche photodiodes · CPC title

• H01L31/107 Primary

  Electricity · mapped topic

• H01L31/02027

  Electricity · mapped topic

• A61B5/0059 Primary

  using light, e.g. diagnosis by transillumination, diascopy, fluorescence (photoacoustic A61B5/0093; optical measurement of heart rate A61B5/02416; optical measurement of blood flow A61B5/0261; optical measurement of analytes A61B5/1455) · CPC title