Image Sensor Gain Control Using Parallel Dummy Pixels
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Solution Overview
Problem
Existing image sensors face challenges in adjusting the gain value of internal amplifiers to effectively handle varying light environments without requiring additional manufacturing steps or components.
Innovation Solution
The image sensor incorporates a pixel array with a controller that connects a target pixel to one or more dummy pixels in parallel, adjusting the gain value of the internal amplifier by varying the number of dummy pixels connected, thereby modifying the input capacitance and amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gain value of the internal amplifier is fixed during manufacturing, then the manufacturing process is simple and cost-effective, but the image sensor cannot adapt to different light environments
Solution Approach 1:
The patent merges the target pixel with dummy pixels by connecting their floating diffusion nodes through switches. This combination allows the image sensor to adjust gain values by dynamically connecting or disconnecting dummy pixels, thereby adapting to different light environments without requiring separate adjustment components for each pixel.
Solution Approach 2:
The dummy pixels serve multiple functions: they act as non-functional elements during normal operation and as gain adjustment elements when connected to target pixels. This multi-functionality enables the image sensor to handle various light conditions using the same hardware structure, improving adaptability without increasing device complexity.
2Adaptability or versatility
If additional capacitors are added to adjust gain value, then the gain adjustment range is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent utilizes existing dummy pixels within the pixel array to provide gain adjustment functionality. Instead of adding external capacitors or adjustment components, the system repurposes the dummy pixels' floating diffusion nodes and associated switches to modify the input capacitance of the internal amplifier, thereby achieving gain adjustment without additional components.
Solution Approach 2:
The patent changes the electrical parameters of the image sensor by dynamically adjusting the input capacitance of the internal amplifier. By connecting or disconnecting dummy pixels through switches, the total capacitance at the amplifier input changes, which directly modifies the gain value. This parameter-based adjustment avoids the need for additional physical components.
3Ease of operation
If dummy pixels are connected in parallel with target pixel, then the input capacitance increases and gain value decreases, but the number of controllable gain levels is limited
Solution Approach 1:
The patent segments the gain adjustment mechanism into multiple switches, each controlling a specific dummy pixel. This segmentation allows for fine-grained control over the gain value, as different combinations of dummy pixels can be connected to achieve multiple discrete gain levels. The segmented approach maintains operational simplicity while increasing the number of controllable gain states.
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 method allows for dynamic adjustment of the gain value without adding separate capacitors, enhancing the sensor's performance across different light conditions without altering the manufacturing process.
Implementation Method 1
a photo sensor configured to generate a photo charge based on received light
Data Source
AI summary
The present technology relates to an image sensor. The image sensor according to an embodiment may include a pixel array in which a plurality of pixels are connected through common lines, an internal amplifier configured to amplify a signal of a target pixel selected from among the plurality of pixels, switches configured to control a connection between the target pixel and floating diffusion nodes of candidate pixels having the same column address as the target pixel among the plurality of pixels, and a controller configured to output control signals for controlling the switches.