Image Sensor Pixel-Group Readout Circuit Area Optimization
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Solution Overview
Problem
Existing image sensors face challenges in achieving high processing speed, which is crucial for biometric recognition applications, due to reduced pixel size and fill factor designs that compromise circuit area for processing.
Innovation Solution
The design of an image sensor with multiple pixel-group sensors, where each group shares a readout circuit and includes a storage circuit, optimizing circuit area usage and enhancing performance by acting as a buffer between the sensor and external processing circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase the number of pixels within a fixed layout area, then image resolution is improved, but the area for arranging processing circuit is reduced, causing processing speed to deteriorate
Solution Approach 1:
The image sensor is divided into multiple pixel groups, with each pixel group sharing a common readout circuit. This segmentation allows multiple pixels to be processed through a single circuit path, reducing the total number of readout circuits needed and freeing up circuit area while maintaining high pixel density for improved resolution
Solution Approach 2:
The readout circuit is designed to handle multiple pixel groups sequentially, making it a universal circuit that serves multiple functions. This multi-functional approach allows a single readout circuit to process signals from multiple pixels, reducing the overall circuit area required and enabling faster processing by optimizing resource utilization
2Use of energy by moving object
If fill factor of pixel is increased to reinforce light sensitivity, then light sensitivity is improved, but the area for arranging processing circuit is reduced, causing processing speed to deteriorate
Solution Approach 1:
By segmenting the sensor into pixel groups that share readout circuits, the circuit area requirement per pixel is reduced, allowing larger fill factors for light-sensitive regions without compromising overall processing capability
Solution Approach 2:
The patent utilizes temporal dimension by implementing sequential readout of pixel groups, allowing multiple pixels to share circuit resources over time. This dimensional approach enables larger pixel fill factors while maintaining processing speed through optimized time-multiplexed circuit utilization
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 allows for improved processing speed and performance by efficiently utilizing limited layout area and reducing frame loss, enabling faster and more accurate biometric recognition.
Implementation Method 1
A floating diffusion node of each of the first pixels is coupled to a first node
Data Source
AI summary
An image sensor including a plurality of pixel-group sensors is provided. Each of the pixel-group sensors includes a first pixel group, a second pixel group and a read out circuit. The first pixel group includes a plurality of first pixels. A floating diffusion node of each of the first pixels is coupled to a first node. The second pixel group includes a plurality of second pixels. A floating diffusion node of each of the second pixels is coupled to a second node. The read out circuit is coupled to the first node and the second node, and configured to compare a voltage of the first node with a voltage of the second node, so as to sequentially obtain a digital pixel value of each of the first pixels and the second pixels.