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

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, the signal configured to enable a gated ring oscillator (GRO) of the TDC;
• and
• measure, using the GRO, 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.

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, the signal configured to enable a gated ring oscillator (GRO) of the TDC;
• measuring, by the TDC and using the GRO, a time interval between when the event occurred and an end of the predetermined event detection time window;
• and
• determining, by a processor, based on the time interval and the predetermined event detection time window, an arrival time of the photon at the photodetector.