Image Sensor Spider Routing for Equal Column Settling Times
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Solution Overview
Problem
The reduction in pixel size and increase in pixel count in image sensors lead to a time constant difference in column lines due to spider routing, resulting in performance degradation.
Innovation Solution
The image sensor design includes a pixel array with column lines connected through interlayer connection regions, where the lengths and distances of wires are optimized to equalize time constants, using additional wires to balance resistance and capacitance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If spider routing is used to transfer pixel outputs to the read circuit, then the chip size is reduced, but a time constant difference occurs in column lines causing performance degradation
Solution Approach 1:
The patent applies local quality by configuring different wire lengths for different column lines. Specifically, column lines are assigned first wires and second wires with different lengths depending on their position and distance to the interlayer connection region. This local differentiation compensates for the time constant differences caused by the spider routing structure, ensuring that each column line has equalized signal transmission characteristics despite varying physical paths.
2Measurement precision
If the number of pixels is increased and pixel size is decreased, then ultra-high-definition imaging is achieved, but time constant difference in column lines increases causing performance reduction
Solution Approach 1:
The patent employs parameter changes by systematically adjusting wire lengths as a compensating parameter. When pixel density increases and column lines are spaced more closely, the patent modifies the lengths of first and second wires for different column lines to equalize their time constants. This parameter adjustment compensates for the increased performance degradation risk associated with higher pixel counts and smaller pixel sizes.
3Quantity of substance
If column lines are spaced closer together, then more pixels can be accommodated, but time constant difference increases leading to performance degradation
Solution Approach 1:
The patent applies local quality by implementing position-dependent wire length configuration. Column lines closer to the interlayer connection region are assigned different wire lengths compared to those farther away. This local differentiation in wire configuration compensates for the time constant differences that arise when column lines are densely spaced, thereby maintaining performance despite increased pixel count.
Data Source
AI summary
An image sensor includes first and second column lines, and a read circuit configured to receive pixel signals through the first and second column lines. The first column line and the second column line each include a main wire, a first wire between one end of the main wire and the first interlayer connection region, and a second wire connected with an opposite end of the main wire. A first distance between the first and second column lines is longer than a second distance between a connection point of the first column line and the first interlayer connection region and a connection point of the second column line and the first interlayer connection region. A length of the first wire of the first column line is greater than a length of the first wire of the second column line.