Image Sensor Cyclic ADC Calibration for β Estimation Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cyclic AD conversion precision degrades due to variations in manufacturing conditions, affecting the accuracy of amplification degree β estimation in cyclic AD conversion circuits.
Innovation Solution
An image capturing device with a cyclic AD conversion system that includes calculators for performing cyclic AD conversion, a comparator, amplification section, switching section, latch section, β estimation signal output section, β estimation section, and binarization section, which estimates the amplification degree β and converts the base β digital value sequence into a binary digital value sequence, reducing precision loss by using β estimation signals and approximate β values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cyclic AD conversion is performed with a fixed amplification degree β, then the conversion process is simple and fast, but manufacturing variations cause degradation of AD conversion precision
Solution Approach 1:
The system performs preliminary estimation of the amplification degree β using dedicated estimation circuits before the main AD conversion process. This preliminary action allows the system to compensate for manufacturing variations in advance, improving conversion precision without significantly increasing the complexity of the main conversion path.
Solution Approach 2:
The patent replaces fixed mechanical amplification with a programmable/digitally controlled amplification system. The amplification degree β is estimated and adjusted through digital processing rather than being fixed by physical circuit parameters, allowing compensation for manufacturing variations while maintaining relatively simple hardware.
2Measurement precision
If the amplification degree β is accurately estimated and used for binarization, then AD conversion precision is improved, but additional circuits and processing steps are required
Solution Approach 1:
The estimation circuits are designed to be multi-functional, serving both to estimate the amplification degree β and to provide calibration data for the main AD conversion process. This universal design improves precision while minimizing additional circuit complexity by making existing circuits perform multiple functions.
Solution Approach 2:
The system uses itself to estimate the amplification degree - the same AD conversion circuits that perform the main conversion function also generate the data needed for β estimation. This self-service approach improves precision without requiring entirely separate estimation hardware, thereby limiting the increase in overall system complexity.
3Productivity
If multiple calculators are used for parallel processing, then productivity is improved, but variations in manufacturing conditions affect each calculator differently, complicating precision maintenance
Solution Approach 1:
Each calculator is equipped with its own β estimation capability or is assigned a specific β value based on its individual characteristics. This local quality approach allows each processing unit to be optimized independently, maintaining precision consistency across parallel calculators despite manufacturing variations, while still achieving high productivity through parallel operation.
Data Source
AI summary
An image capturing device includes: an image capturing section having a plurality of pixels disposed in a matrix and configured to output a pixel signal via a first signal line connected to pixels arranged in a first direction among the plurality of pixels; a plurality of calculators including: a comparator configured to compare a magnitude of a first analog signal with a threshold value to generate a digital value according to a comparison result; an amplification section configured to amplify the first analog signal by multiplying the first analog signal by an amplification degree β (1<β<2) and output a second analog signal by executing computation according to the digital value; and a switching section configured to output one of the pixel signal and a β estimation signal as the first analog signal when a most significant bit of a first digital value sequence is computed.