Pixel Array Circuit Layout for Uniform Image Sensor Readout
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Solution Overview
Problem
Existing solid-state image capturing devices experience image quality deterioration due to characteristic differences among pixel columns and rows, temperature distribution, power supply variations, and interference between digital and analog signals, as described in Japanese Patent Application Laid-Open No. 2016-92791.
Innovation Solution
The proposed solution involves a pixel array with multiple signal lines connected to circuit groups, where transistors with the same function are arranged adjacently in a column direction to reduce process variations and temperature differences, and comparators are arranged to prevent color mixture by separating their outputs, with a stacked-layer structure to uniformize signal line lengths and reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transistors with the same function are arranged adjacently in columns to uniformize element characteristics, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The pixel array is divided into multiple blocks, with each block containing a specific number of pixels and corresponding circuit groups. This segmentation allows for systematic arrangement of transistors with the same function in adjacent columns within each block, achieving characteristic uniformity while managing device complexity through modular organization.
Solution Approach 2:
Multiple circuit groups (first, second, third, and fourth circuit groups) are merged into a unified structure where transistors with the same function are positioned adjacently in columns. This merging approach uniformizes element characteristics across different circuit groups while maintaining a structured, manageable layout.
2Measurement precision
If multiple signal lines are provided for each pixel column to reduce color mixture, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The signal lines are segmented into multiple distinct lines (first, second, third, and fourth signal lines) for each pixel column, with each line dedicated to specific color channels. This segmentation reduces color mixture by providing separate transmission paths while organizing the complexity through systematic assignment of signal lines to specific pixel and circuit group combinations.
Solution Approach 2:
The multiple signal lines act as intermediaries between the pixel array and the circuit groups, providing dedicated transmission paths that prevent color mixture. The first signal line connects to the first circuit group, the second signal line to the second circuit group, and so on, creating a clear intermediary structure that maintains signal integrity.
3Reliability
If analog and digital circuits are separated to prevent interference, then reliability is improved, but device complexity increases
Solution Approach 1:
The circuit groups are segmented into distinct analog and digital sections, with the first and second circuit groups handling analog signal processing and the third and fourth circuit groups handling digital signal processing. This segmentation prevents interference between analog and digital circuits while organizing the device into manageable functional blocks.
Solution Approach 2:
Digital circuit functions are extracted and separated from analog circuit functions into distinct circuit groups. The digital signal processing circuits are positioned separately from the analog pixel readout circuits, removing the source of interference while maintaining a structured layout that manages the overall device complexity.
Data Source
AI summary
A device includes a pixel array including a plurality of pixels, a first pixel and a second pixel of the plurality of pixels corresponding to different colors, the first pixel and a third pixel of the plurality of pixels corresponding to a same color, a first circuit group connected to the first pixel, a third circuit group connected to the third pixel, and a first circuit included in the first circuit group, a second circuit, and a third circuit included in the third circuit group and having a function same as a function of the first circuit, the third circuit being arranged between the first circuit and the second circuit in a top view.