Quanta Image Sensor Pixels With Auto-Zeroing for Single-Photon Timing
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Solution Overview
Problem
Current high-speed photonic detection systems face challenges in reliably reporting single photon strikes with high resolution and precision, particularly in extremely brief event-detection intervals, due to issues like photodetector saturation and noise interference.
Innovation Solution
The implementation of multi-stage auto-zeroing signal amplifiers within event-shuttering pixels of a quanta image sensor (QIS) enables reliable per-pixel reporting of photonic events by executing auto-zero operations at the end of each detection interval, preventing cross-interval interference and using both active and inactive photo-signal generators to provide differential signals for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If photodetectors operate continuously to detect photonic events, then detection coverage is improved, but photodetector saturation occurs leading to loss of information
Solution Approach 1:
The continuous detection period is segmented into discrete event-detection intervals separated by reset intervals. During reset intervals, photonic events are not detected, allowing photodetectors to clear accumulated charge and avoid saturation. This segmentation enables continuous operation over extended periods while preventing information loss from saturation.
Solution Approach 2:
The system employs periodic reset operations at predetermined intervals during which photonic event detection is suspended. This periodic action clears accumulated charge in photodetectors before saturation occurs, enabling reliable detection across varying light intensities and extended time periods.
2Quantity of substance
If event-detection intervals are extended to capture more events, then detection quantity is improved, but timing precision deteriorates
Solution Approach 1:
The system dynamically adjusts the duration of event-detection intervals based on operational requirements. By making the interval length adjustable rather than fixed, the system can optimize for either quantity or precision depending on the application, resolving the trade-off between detecting more events and maintaining timing precision.
Solution Approach 2:
The duration of event-detection intervals is changed as a controllable parameter. By varying this parameter, the system can capture more events when interval length is increased, while maintaining timing precision through the use of precise timing circuits that accurately measure event timestamps even within longer intervals.
3Reliability
If photodetectors are reset frequently to prevent saturation, then reliability is improved, but detection intervals are reduced
Solution Approach 1:
Photodetectors are reset in advance during predetermined reset intervals before saturation can occur. This preliminary action ensures that photodetectors are ready to reliably detect events in the subsequent event-detection interval, maintaining high reliability while maximizing the duration of productive detection periods.
Solution Approach 2:
The system maintains continuous useful action by alternating between event-detection intervals and reset intervals in a seamless cycle. During event-detection intervals, photonic events are detected with high reliability; during reset intervals, photodetectors are prepared for the next detection cycle. This continuous cycling ensures both reliability and maximized detection duration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for reliable detection of single photon strikes with resolution down to 100 nanosecond intervals, preventing photodetector saturation and achieving reliable data generation across a range of light intensities, thereby improving the precision and reliability of photonic event detection.
Implementation Method 1
each pixel comprising a photodetector
Data Source
AI summary
Multi-stage auto-zeroing signal amplifiers are deployed within event-shuttering pixels of a quanta image sensor (QIS) pixel array to enable reliable per-pixel reporting of photonic events, down to resolution of a single photon strike, for each of a continuous sequence of sub-microsecond event-detection intervals.