Image Sensor Transfer Gate Uniformity via Local Quality
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Solution Overview
Problem
Existing image sensing devices face challenges in maintaining uniform photocharge collection and transfer capabilities across different locations in a pixel array, leading to noise issues due to IR drop, which affects the accuracy of distance measurement in applications like automotive and medical devices.
Innovation Solution
The image sensing device incorporates a pixel array with transfer gates of varying structures, including depth and material variations, to ensure uniform photocharge collection and transfer capabilities regardless of location, minimizing noise caused by IR drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transfer gates with different structures are used for pixels at different locations, then photocharge collection and transfer uniformity is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by configuring transfer gates with different structures at different locations within the pixel array. Specifically, transfer gates closer to the transmission driver have different channel widths, lengths, or threshold voltages compared to those farther away, compensating for the IR drop effect and ensuring uniform photocharge collection and transfer characteristics across the entire array.
2Adaptability or versatility
If transmission signal lines are extended to reach distant pixels, then all pixels can be controlled, but voltage drop increases causing non-uniform operation
Solution Approach 1:
The patent changes the electrical parameters of the transfer gates to compensate for signal transmission issues. By adjusting the threshold voltage, channel width, or channel length of transfer gates based on their distance from the transmission driver, the patent ensures that all pixels receive adequate control signals despite the IR drop in extended transmission lines.
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 enables uniform pixel signal generation across the array, reducing noise and improving the accuracy of distance measurement by maintaining consistent photocharge transfer efficiency and collection capabilities.
Implementation Method 1
image sensor pixels that generate photocharges in response to light
Data Source
AI summary
An image sensing device includes a plurality of image sensor pixels including a first image sensor pixel and a second image sensor pixel and a transmission driver. The transmission driver is coupled to first and second transfer gates to apply a first transmission signal to the first transfer gate to control the first transfer gate and a second transmission signal to the second transfer gate to control the second transfer gate. A first distance between the first image sensor pixel and the transmission driver is shorter than a second distance between the second image sensor pixel and the transmission driver, and the first and second transfer gates of the first image sensor pixel are different in structure from the first and second transfer gates of the second image sensor pixel, respectively.