Quanta Image Sensor Pixels With Auto-Zeroing for Single-Photon Detection
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Solution Overview
Problem
Current high-speed photonic detection systems face challenges in reliably reporting photonic events at the single-photon level with high resolution and precision, particularly in 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-talk and allowing for pipelined readout, with both active and inactive photo-signal generators providing differential signals to ensure accurate and independent event reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-stage auto-zeroing signal amplifiers are implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The signal amplifier is divided into multiple stages (first-stage pixel-signal amplifier, second-stage differential amplifier, third-stage single-drive amplifier, and final-stage common-mode amplifier), with each stage performing a specific function in the signal processing chain. This segmentation allows complex auto-zeroing operations to be broken down into manageable stages, improving measurement precision while making the overall complexity more controllable through modular design.
Solution Approach 2:
The auto-zeroing operation is executed at the end of each detection interval before the next interval begins. This preliminary action resets the amplifier stages to a known state, preventing noise accumulation and ensuring consistent measurement precision across multiple detection intervals, while the timing structure manages complexity by confining zeroing operations to specific time windows.
2Reliability
If event-shuttering pixels with auto-zeroing are used, then reliability of photonic event reporting is improved, but loss of time increases
Solution Approach 1:
The system operates in periodic cycles consisting of detection intervals followed by auto-zeroing intervals. During detection intervals, photonic events are recorded with high reliability; during subsequent auto-zeroing intervals, the amplifier stages are reset. This periodic structure ensures reliable event reporting while minimizing time loss by efficiently utilizing the transition periods between detections.
Solution Approach 2:
The pipelined readout architecture allows continuous operation by overlapping detection, readout, and zeroing operations across multiple pixel rows. While one row is being read out, another row can be detected, and a third can be zeroed, maintaining continuous useful action and reducing overall time loss.
3Measurement precision
If both active and inactive photo-signal generators are implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The inactive photo-signal generator acts as a reference or mediator that experiences the same environmental conditions (temperature, noise, interference) as the active generator but does not detect photonic events. By comparing the output of the active generator against this reference, the system can subtract common-mode noise and interference, significantly improving measurement precision while adding only one additional structure per pixel.
Solution Approach 2:
The inactive photo-signal generator provides a counterbalancing reference signal that weights against the noise and interference components in the active generator's output. This counterweight approach allows the differential amplifier to reject common-mode signals and isolate the true photonic event signals, improving precision with minimal additional complexity.
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 events with minimal noise interference, enabling precise event reporting across a broad range of light intensities and improving the overall performance of high-speed photonic detection systems.
Implementation Method 1
a photodetector output cumulatively decrements by as little as 1e− (single electron), executing an auto-zero 'event shuttering' operation
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.