Pixel Layout for Central Charge Transfer in Image Sensors
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Solution Overview
Problem
Existing image sensing devices face challenges in achieving high resolution and high sensitivity due to limitations in transconductance and conversion gain, which affect charge transfer efficiency and noise performance.
Innovation Solution
The image sensing device is designed with a novel pixel structure where transfer transistors and floating diffusion regions are positioned at the central regions of photodiodes, reducing the distance between the transfer transistors and photodiode edges, and incorporating a specific arrangement of pixel transistors to improve charge transfer efficiency and transconductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transfer transistors are positioned at the central regions of photodiodes to reduce charge transfer distance, then charge transfer efficiency is improved, but device layout complexity increases
Solution Approach 1:
The transfer transistor is specifically positioned at the central region of the photodiode, creating a localized optimal charge transfer path. This local structural optimization improves charge transfer efficiency without requiring complete redesign of the entire device layout, thereby resolving the contradiction between improved productivity and increased complexity.
2Productivity
If floating diffusion regions are positioned closer to photodiode edges, then charge collection efficiency is improved, but noise performance deteriorates
Solution Approach 1:
The transfer transistor positioned at the central region acts as an intermediary between the photodiode and the floating diffusion region. It efficiently collects charges from the photodiode and transfers them to the floating diffusion region, thereby improving charge collection efficiency while maintaining noise performance through the controlled transfer process, resolving the contradiction between productivity and harmful factors.
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 configuration enhances charge transfer efficiency, improves transconductance, secures conversion gain, and reduces noise, allowing for improved performance with reduced power consumption.
Implementation Method 1
Each of the pixels may include a photodiode that receives light and generates electrical signals based on the light received
Data Source
AI summary
Image sensing devices are disclosed. In an embodiment, an image sensing device includes a plurality of pixels, each of which includes at least one sub-pixel. The sub-pixel may include a photodiode, a transfer transistor and a plurality of pixel transistors. The transfer transistor may transfer a charge generated in the photodiode to a diffusion region. The plurality of the pixel transistors may generate a pixel signal based on the charge received from the transfer transistor. The transfer transistor is positioned closer to a center of the sub-pixel than each of the plurality of the pixel transistors.