Delta-Sigma ADC Timing Groups for Stable Image Sensor Conversion
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Solution Overview
Problem
In solid-state image capturing apparatuses using delta-sigma AD converters, transient power supply and ground potential fluctuations due to simultaneous output inversions from multiple converters lead to decreased accuracy and image quality.
Innovation Solution
Divide delta-sigma AD converters into groups with different starting conversion timings to mitigate potential fluctuations, ensuring synchronized operations and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple delta-sigma AD converters operate simultaneously with synchronized timing, then conversion speed and productivity are improved, but potential fluctuations occur causing decreased conversion accuracy and image quality
Solution Approach 1:
The patent divides the simultaneously operating delta-sigma AD converters into multiple groups (first group and second group). Each group operates with different timing, specifically different inversion timings for their quantizer outputs. This segmentation prevents simultaneous potential fluctuations while maintaining high overall conversion throughput, thus resolving the contradiction between productivity and measurement precision.
2Device complexity
If delta-sigma AD converters use common power supply and ground connections, then device complexity is reduced, but transient potential fluctuations occur during operation
Solution Approach 1:
The patent segments the power supply structure by providing separate power supply lines and ground lines for different groups of delta-sigma AD converters. Specifically, first power supply/ground lines serve the first group while second power supply/ground lines serve the second group. This segmentation isolates transient potential fluctuations to individual groups, preventing system-wide interference while maintaining operational reliability.
3Ease of operation
If quantizer output inversion timing is synchronized across all delta-sigma AD converters, then operational coordination is simplified, but mutual interference occurs causing variation in inversion timings
Solution Approach 1:
The patent divides converters into groups with different inversion timings. The first group inverts quantizer outputs at one timing while the second group inverts at a different timing. This segmentation maintains simple group-level coordination while eliminating mutual interference between converters, ensuring accurate inversion timing within each group.
Solution Approach 2:
The patent implements periodic action by alternating the inversion timing between different groups of converters. Instead of all converters inverting simultaneously, they operate in staggered periodic cycles. This approach maintains operational coordination while preventing the mutual interference that would occur with fully synchronized inversion timing.
Data Source
AI summary
A photoelectric conversion device comprising a pixel unit in which a plurality of pixels each comprising a photoelectric conversion element are arranged in a matrix, and a plurality of delta-sigma AD converters each configured to convert a signal output from the pixel unit into a digital signal, is provided. The plurality of delta-sigma AD converters are divided into at least two groups having different timings of starting AD conversion from each other when converting, into digital signals, signals output from the pixels selected out of the plurality of pixels via a common pixel control line.