Active Pixel Memory Structure for Faster Correlated Double Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pixel structures are limited by extended reset times, which slow down pixel operation due to the need to perform correlated double sampling, a technique that requires time for both reset and signal voltage sampling.
Innovation Solution
The implementation of an active pixel structure with multiple memory elements, including capacitors as part of sample and hold stages, allows for pre-charging and efficient storage of reset and signal voltages, enabling faster correlated double sampling by separating the reset and integration periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel uses conventional reset time extension to accommodate correlated double sampling calculation, then the correlated double sampling can be performed, but the pixel operation rate is reduced
Solution Approach 1:
The patent applies preliminary action by storing the reset voltage in a memory element before the correlated double sampling calculation is performed. This allows the reset voltage to be readily available when needed, eliminating the need to extend the reset time to accommodate the calculation. The memory element holds the reset voltage ready for immediate subtraction from the signal voltage, thus improving pixel operation rate while maintaining reliable correlated double sampling.
2Measurement precision
If the pixel uses extended reset time to complete correlated double sampling, then noise removal is achieved, but the speed of pixel operation is reduced
Solution Approach 1:
The patent stores the reset voltage in a memory element in advance, before the signal voltage is read out. This preliminary storage action allows the correlated double sampling subtraction to be performed quickly without extending the reset time, thus maintaining high pixel operation speed while achieving effective noise removal through the subtraction process.
Solution Approach 2:
The patent replaces the time-consuming sequential process with an electronic storage and retrieval system. Instead of waiting for the reset calculation to complete before proceeding, the system uses memory elements to store voltages and electronic circuitry to perform rapid subtraction, substituting electronic operations for time-based sequential processing and thereby increasing pixel operation speed.
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 higher pixel operation rates by reducing the time needed for reset and correlated double sampling, allowing for faster and more efficient noise removal without extending the reset time, thus enhancing the speed and efficiency of pixel operations.
Implementation Method 1
a sensor circuit for collecting radiation induced charges and for transducing them to a measurement signal corresponding to the amount of charge collected
Implementation Method 2
The memory elements may be capacitors
Data Source
AI summary
A method and apparatus for performing correlated double sampling to remove low frequency noise. The method and apparatus includes an active pixel of an array of active pixels comprising a sensor circuit for collecting radiation induced charges and transducing them to a measurement signal corresponding to the amount of charge collected, two memory elements for storing the measurement signal at the beginning and the end of a first integration period respectively, and at least one further memory element for storing at least the measurement signal at the beginning of a next integration period.