Image Sensor Comparator Control Line Layout for Crosstalk Suppression
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Solution Overview
Problem
Existing image pickup apparatuses experience crosstalk errors due to shared signal lines for control signals, leading to decreased image quality in analog-to-digital conversion.
Innovation Solution
An image pickup apparatus with a signal line control unit that sets the electric potential of the signal line to a fixed potential, reducing fluctuations and crosstalk between comparators by positioning the signal line control unit between the control signal generation unit and the signal line, thereby minimizing errors in AD conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common signal line is used to supply control signals to multiple comparators, then device complexity is reduced, but crosstalk occurs between comparators causing AD conversion errors
Solution Approach 1:
The patent divides the common signal line into multiple independent signal lines, with each signal line dedicated to controlling a specific comparator. This segmentation eliminates crosstalk between comparators while maintaining the benefit of integrated control, as each comparator receives its control signal through a dedicated pathway without interference from other comparators.
Solution Approach 2:
The patent applies different signal line configurations to different comparators based on their specific requirements. By providing dedicated signal lines to comparators that are prone to crosstalk while maintaining common signal lines for comparators with lower interference risk, the system optimizes the balance between complexity and precision locally.
2Measurement precision
If the control signal amplitude is restricted to reduce offset, then comparator calibration accuracy is improved, but control signal effectiveness may be reduced
Solution Approach 1:
The patent applies offset compensation to comparators before the actual AD conversion process. By performing calibration and offset correction in advance through dedicated control signal lines, the system ensures that comparators are properly calibrated without requiring high-amplitude control signals during the main conversion operation, thus maintaining both accuracy and power efficiency.
Solution Approach 2:
The patent implements feedback mechanisms where comparator outputs are monitored and used to adjust control signals dynamically. This feedback allows the system to maintain optimal control signal amplitudes that are sufficient for accurate comparison while minimizing offset errors, as the system continuously adapts the control signal strength based on actual comparator performance.
Data Source
AI summary
An image pickup apparatus includes a plurality of pixels arranged in rows and columns, a plurality of comparators, each of the comparators including a switch for controlling an operation, a signal line which is provided commonly to the switches of the plurality of comparators and through which a control signal for controlling the switches of the plurality of comparators is supplied, a control signal generation unit, and a signal line control unit configured to control an electric potential of the signal line to be set as a fixed electric potential.