Photosite Charge Flow Paths for iToF Sensor Bulk Reduction
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Solution Overview
Problem
Indirect Time-of-Flight (iToF) sensors face challenges in reducing the bulk and power consumption of their photosites, which are essential for efficient depth data acquisition and integration in arrays, especially when combined with color or black and white pixels.
Innovation Solution
The photosite design incorporates a photoconversion area with two charge flow paths, where one path is unidirectional and without a switch, allowing all charges to flow when the other paths are closed, and the other path is controllable with a switch, prioritizing the controllable path for sampling and resetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a single photosite with multiple charge flow paths is used, then the bulk and power consumption are reduced, but the ability to acquire multiple phase-shifted samples per integration phase is limited
Solution Approach 1:
The patent implements dynamic switching between different charge flow paths using controllable switches. The first charge flow path includes a first switch that can be controlled to direct charges to different nodes (first node or second node) based on the integration phase, enabling the photosite to adaptively acquire different numbers of samples at different phases while maintaining a compact structure.
Solution Approach 2:
The single photosite is designed with multiple charge flow paths that can serve different functions depending on the switching state. The same photosite structure can acquire 1, 2, or 3 samples per integration phase by controlling the switches, making it a multi-functional component that replaces what would traditionally require multiple separate photosites.
2Productivity
If multiple photosites are used to acquire all samples in one integration phase, then sampling capability is improved, but the bulk and integration complexity increase
Solution Approach 1:
The patent merges the functionality of multiple photosites into a single photosite by providing multiple charge flow paths within one photosite structure. This consolidation reduces the total number of photosites needed in the array while maintaining the capability to acquire multiple samples per integration phase, thereby reducing integration complexity.
Solution Approach 2:
The charge flow paths are segmented into multiple independent paths (first charge flow path with first switch, second charge flow path, third charge flow path) that can be independently controlled. This segmentation allows flexible configuration of sampling modes without requiring separate photosites for each sampling function.
3Adaptability or versatility
If controllable switches are added to manage charge flow paths, then sampling flexibility is improved, but power consumption increases
Solution Approach 1:
The switches are controlled in a periodic manner synchronized with the integration phases. During each integration phase, the switches are activated only when needed to direct charges to specific nodes, and remain inactive otherwise. This periodic control minimizes the power consumption of the switches while maintaining the flexibility to configure different sampling modes.
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 design reduces the bulk and power consumption of the photosite, simplifies the sensor's integration, and eliminates the need for complex control signals, thereby enhancing the efficiency and compactness of iToF sensors.
Implementation Method 1
a photoconversion area configured to convert light into charges
Data Source
AI summary
The present description concerns a photosite including: a photoconversion area configured to convert light into charges; at least one assembly of a first node and of a first charge flow path including a first switch configured to allow the flowing of charges from the photoconversion area to the first node of said assembly when said first switch is on and block the passage of charges between the photoconversion area and the first node of said assembly when said first switch is off; and a second charge flow path between said photoconversion area and a second node of the photosite, wherein the first and second paths are configured so that each first path holds the priority over the second path when the first switch of said first path is on.