Geiger-Mode APD Focal Plane Bias Correction for Pixel Uniformity
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Solution Overview
Problem
Variations in breakdown voltage among pixels in focal plane arrays (FPAs) lead to inconsistent performance, reducing the accuracy and effectiveness of sensors used in autonomous vehicles, such as lidar systems, due to the inability to compensate for individual pixel variations in existing systems.
Innovation Solution
A system and method that utilize a readout integrated circuit (ROIC) to read and store characteristics of each pixel in a pixelated photodiode array, allowing for the adjustment of arm/disarm bias voltage for each pixel based on its specific characteristics, thereby compensating for breakdown voltage variations and achieving uniform detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single voltage bias is applied to all pixels in the FPA, then the device complexity is reduced and ease of operation is improved, but the performance uniformity and detection accuracy deteriorate due to breakdown voltage variations among pixels
Solution Approach 1:
The patent divides the uniform voltage biasing system into pixel-specific segments. Each pixel receives an individually adjusted voltage bias based on its measured breakdown voltage, transforming a single unified system into multiple customized subsystems. This segmentation resolves the contradiction by allowing precise control for each pixel while maintaining overall system manageability through automated calibration.
Solution Approach 2:
The patent implements local quality by applying different voltage bias values to different pixels based on their individual characteristics. Instead of uniform treatment, each pixel's bias voltage is locally optimized according to its specific breakdown voltage measurement, ensuring optimal performance for each element while accounting for manufacturing variations.
2Measurement precision
If pixel-level voltage adjustment is implemented to compensate for breakdown voltage variations, then detection accuracy and performance uniformity are improved, but the device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by measuring and storing the breakdown voltage of each pixel during the manufacturing or initialization phase. These pre-measured values are then used to calculate and apply appropriate compensation voltages during operation, eliminating the need for real-time measurements and reducing operational complexity despite the increased initial setup requirements.
Solution Approach 2:
The patent implements feedback by using the measured breakdown voltage information to adjust the operating voltage of each pixel. This closed-loop approach ensures that each pixel operates at its optimal voltage level, compensating for manufacturing variations and maintaining high detection accuracy across the entire FPA array.
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 enhances the detection capabilities and accuracy of sensors by ensuring uniform performance across all pixels, improving the overall navigation and decision-making processes in autonomous vehicles, while also increasing the yield of FPA modules by allowing for the use of previously non-performing devices.
Implementation Method 1
Geiger-mode avalanche photodiode (GMAPD) devices
Data Source
AI summary
An apparatus includes a pixelated photodiode array (PDA). Each pixel in the PDA includes a radiation detector, a memory configured to store a negative bias voltage for the PDA and a nominal breakdown voltage for each pixel in the PDA, and a read out integrated circuit (ROIC) communicatively coupled to the PDA and the memory. The ROIC is configured to read, from the memory, the negative bias voltage for the PDA and the nominal breakdown voltage for each pixel in the PDA, determine a difference between the negative bias voltage for the PDA and the nominal breakdown voltage for each pixel in the PDA, and adjust an arm/disarm bias voltage for each pixel in the PDA based on the difference between the negative bias voltage for the PDA and the nominal breakdown voltage for each pixel in the PDA.