ToF Depth Pixel Common Photogate Multi-Tap Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current time-of-flight (ToF) sensors face challenges in reducing size and power consumption while maintaining high sensing accuracy and sensitivity for distance measurement in three-dimensional imaging applications.
Innovation Solution
A depth pixel design for ToF sensors featuring a common photogate in the center region, surrounded by floating diffusion regions and demodulation transfer gates, with symmetric structures to enhance photo charge transfer and overflow gates for efficient charge drainage, reducing power consumption and size while increasing sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional ToF sensor design is used, then the sensing accuracy and sensitivity can be maintained, but the size and power consumption are large
Solution Approach 1:
The patent merges multiple photogate functions into a single common photogate structure that serves multiple floating diffusion regions simultaneously. This consolidation reduces the total number of photogates and associated circuitry, thereby reducing power consumption while maintaining the ability to perform phase-demodulated detection across multiple pixels.
Solution Approach 2:
The common photogate is designed to serve multiple functions by collecting photo charges from multiple floating diffusion regions through controlled charge transfer. This multi-functional design allows a single photogate structure to replace what would traditionally require multiple separate photogates, reducing overall power consumption while preserving sensing accuracy.
2Measurement precision
If a conventional ToF sensor design is used, then the sensing accuracy and sensitivity can be maintained, but the size is large
Solution Approach 1:
The patent merges multiple photogate structures into a single common photogate that serves multiple floating diffusion regions. This consolidation significantly reduces the total area occupied by photogate circuitry and associated components, enabling smaller sensor size while maintaining sensing accuracy through the shared photogate structure.
Solution Approach 2:
The patent segments the charge collection function across multiple floating diffusion regions while using a single common photogate. This segmentation allows the sensor to maintain multiple detection channels for accurate phase measurement while reducing the overall area by eliminating redundant photogate structures between each channel.
3Reliability
If the photogate is moved to the center region, then the symmetric structure enhances photo charge transfer, but the floating diffusion regions must be rearranged
Solution Approach 1:
The patent employs symmetric arrangement of floating diffusion regions around the central photogate to ensure balanced and reliable photo charge transfer. The symmetric configuration allows equal and efficient charge collection from all directions, improving reliability while the regular pattern actually simplifies the overall structural arrangement compared to asymmetric designs.
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
The design effectively reduces the size and power consumption of ToF sensors while enhancing sensing accuracy and sensitivity, improving overall performance in distance measurement tasks.
Implementation Method 1
a common photogate disposed in a center region of the depth pixel... configured to collect photo charges
Implementation Method 2
a plurality of demodulation transfer gates disposed in a peripheral region and configured to transfer photo charges collected by the common photogate to the plurality of floating diffusion regions
Data Source
AI summary
A depth pixel of a time-of-flight (ToF) sensor includes a common photogate disposed in a center region of the depth pixel, a plurality of floating diffusion regions disposed in a peripheral region surrounding the center region, a plurality of demodulation transfer gates disposed in the peripheral region, and a plurality of overflow gates disposed in the peripheral region. The demodulation transfer gates transfer a photo charge collected by the common photogate to the plurality of floating diffusion regions. The demodulation transfer gates are symmetric with respect to each of a horizontal line and a vertical line that pass through a center of the depth pixel and are substantially perpendicular to each other. The overflow gates drain the photo charge collected by the common photogate, and are symmetric with respect to each of the horizontal line and the vertical line.