Image Sensor Path Change Circuits for Readout Mismatch Reduction
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Solution Overview
Problem
Image sensing devices face mismatches between readout circuits, leading to row fixed pattern noise (RFPN), which affects the accuracy and quality of captured images.
Innovation Solution
The image sensing device incorporates first and second path change circuits that alter the coupling relationships between column lines and readout circuits based on control signals, allowing unit pixel circuits to be dynamically coupled to readout circuits, thereby reducing mismatches and improving signal readout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed coupling relationships are used between column lines and readout circuits, then device complexity is reduced, but mismatch between readout circuits increases causing row fixed pattern noise
Solution Approach 1:
The patent implements dynamic path switching between column lines and readout circuits using path change circuits controlled by control signals. Instead of fixed coupling, the system dynamically reconfigures connections to randomly assign pixel circuits to readout circuits, thereby reducing row fixed pattern noise while maintaining manageable device complexity through systematic control.
2Reliability
If path change circuits are added to reduce mismatch, then image sensing accuracy improves, but device complexity increases
Solution Approach 1:
The patent divides the readout circuit system into multiple independent readout circuits (first, second, third, fourth readout circuits) each handling specific column lines through path change circuits. This segmentation allows independent optimization of each readout path while reducing overall mismatch effects, balancing improved reliability with controlled device complexity.
3Object-generated harmful factors
If random coupling is implemented between pixel circuits and readout circuits, then row fixed pattern noise decreases, but control complexity increases
Solution Approach 1:
The patent employs periodic switching of path configurations between different time periods. During first time periods, certain path configurations are activated; during second time periods, different configurations are used. This periodic action enables random coupling effects to reduce row fixed pattern noise while maintaining systematic and manageable control signal complexity through regular switching patterns.
Data Source
AI summary
An image sensing device includes first to fourth column lines disposed sequentially in a row direction, first and third unit pixel circuits arranged in a first row and coupled to the first and third column lines, respectively, second and fourth unit pixel circuits arranged in a second row and coupled to the second and fourth column lines, respectively, first to fourth readout circuits, a first path change circuit for changing first and second paths so that the first and second unit pixel circuits are coupled to the first and second readout circuits according to a first relationship during a first unit time, and a second path change circuit for changing third and fourth paths so that the third and fourth unit pixel circuits are coupled to the third and fourth readout circuits according to a second relationship during the first unit time.