Split SPAD Microcells for Faster Silicon Photomultiplier Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensors suffer from limited functionality, including inability to determine object distance and lower-than-desired image quality and resolution, and single-photon avalanche diodes (SPADs) have long recovery times that hinder performance.
Innovation Solution
The use of SPADs with passive or active quenching circuitry and silicon photomultipliers, where SPADs are grouped together to increase dynamic range and reduce recovery time by splitting microcells into segments, allowing for faster photon detection and improved image resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-photon avalanche diodes (SPADs) are used to improve sensitivity to incident light, then sensitivity is improved, but recovery time between avalanches increases resulting in poor performance
Solution Approach 1:
The microcell is divided into two separate segments: a first microcell segment and a second microcell segment. Each segment has its own quenching circuitry and output contact. This segmentation allows the photomultiplier to process avalanches in parallel across segments, effectively reducing the recovery time while maintaining high sensitivity for single-photon detection.
2Ease of manufacture
If conventional image sensors are used, then manufacturing is simpler, but functionality is limited including inability to determine object distance
Solution Approach 1:
The silicon photomultiplier with split microcells provides multiple functions within a single device: it can perform single-photon detection, depth sensing through time-of-flight measurement, and image capture. The SPAD-based architecture enables both imaging and depth mapping capabilities, making the sensor versatile for various applications including augmented reality, 3D scanning, and low-light imaging.
3Device complexity
If conventional image sensors are used, then device structure is simpler, but image quality and resolution are lower than desired
Solution Approach 1:
By dividing each microcell into two segments with independent quenching circuitry, the device achieves faster recovery times and reduced dead time between photon detections. This segmentation improves the effective detection rate and image quality, particularly in scenarios with high photon flux or rapid scene changes.
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 sensitivity and resolution of imaging systems by reducing recovery time and increasing dynamic range, enabling effective low-light imaging and depth sensing.
Implementation Method 1
single-photon avalanche diodes (SPADs) may be capable of single-photon detection
Implementation Method 2
Each pixel typically includes a photosensitive element (such as a photodiode) that receives incident photons (light) and converts the photons into electrical signals
Implementation Method 3
SPADs with passive or active quenching circuitry
Data Source
AI summary
A semiconductor device may include a plurality of single-photon avalanche diodes. The single-photon avalanche diodes may be arranged in microcells. Each microcell may be a split microcell with first and second independent microcell segments. Each microcell segment in the split microcell may have a respective single-photon avalanche diode that is coupled to an output line. The single-photon avalanche diode of each microcell segment may also be coupled to a respective resistor that is used to quench avalanches in the single-photon avalanche diode. Splitting the microcell may reduce the recovery time of each microcell. The segments of the split microcell may be positioned close together, even if susceptible to optical crosstalk. Intra-microcell isolation structures may be formed between the microcell segments. Inter-microcell isolation structures may be formed around a perimeter of the split microcell. The intra-microcell and inter-microcell isolation structures may be different.