Serial Read-Out Architecture With Balanced Gate-Group Delays
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Solution Overview
Problem
Conventional architectures for CMOS image sensors face inefficiencies in serializing and reading out large volumes of digital data from counter circuits, leading to bottlenecks in pixel conversion performance due to unbalanced clock and data path delays and high power consumption.
Innovation Solution
A serial read-out architecture that balances total path delays across gate groups by controlling clock and data path delays inversely, using a partitioned bus to manage data bus capacitance and ensure all gate groups operate within a single clock period, allowing for efficient high-speed serialization of digital bit values from multiple digital data sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional serialization architecture is used to read out digital data from counter circuits, then the system can output pixel conversion values, but the unbalanced clock and data path delays cause bottlenecks in read-out speed
Solution Approach 1:
The patent segments the serialization architecture into multiple gate groups (first gate group, second gate group, etc.), each handling a subset of counter circuits. This segmentation allows independent optimization and balancing of clock and data path delays for each gate group, preventing the unbalanced delays that bottleneck conventional unified architectures.
Solution Approach 2:
The patent applies local quality by providing different clock path delays to different gate groups based on their specific requirements. Each gate group receives customized clock and data path delay configurations to achieve balanced total path delays locally, rather than applying a uniform delay configuration across the entire system.
2Productivity
If high-speed clock operation is implemented to increase pixel conversion speed, then conversion performance improves, but power consumption increases
Solution Approach 1:
The patent uses periodic clock signals with optimized periods to drive the serialization process. By carefully controlling the clock period and synchronizing data latching with clock edges, the system achieves high-speed operation only when necessary, reducing unnecessary power consumption associated with continuous high-speed operation.
Solution Approach 2:
The patent implements dynamic control of clock and data path delays, adjusting them based on the specific requirements of each gate group and operational conditions. This dynamic optimization allows the system to achieve high conversion speeds when needed while reducing power consumption during normal operation by minimizing unnecessary delay adjustments.
3Quantity of substance
If more transmission gates are used to handle data from more counter circuits, then data throughput increases, but path delay becomes unbalanced and complexity increases
Solution Approach 1:
The patent divides the large number of transmission gates into multiple gate groups, each managing a subset of counter circuits. This segmentation reduces the complexity of controlling and balancing delays across all transmission gates by breaking them into manageable units that can be independently optimized.
Solution Approach 2:
The patent achieves equipotentiality by balancing the total path delays (clock delay + data delay) across all gate groups. By ensuring that each gate group experiences comparable total delays, the system maintains synchronized operation without requiring complex individual delay control for each transmission gate, thus reducing overall architectural complexity.
4Stability of the object's composition
If clock path delay is increased to synchronize data arrival, then data synchronization improves, but overall read-out time increases
Solution Approach 1:
The patent applies local quality by providing different clock path delays to different gate groups based on their specific data path characteristics. Each gate group receives the precise amount of clock delay needed to synchronize data arrival at its output flop, avoiding the need to increase clock delay system-wide and thus preventing overall read-out time increases.
Solution Approach 2:
The patent changes the clock path delay parameter selectively for each gate group to achieve optimal synchronization. By adjusting this parameter locally rather than globally, the system maintains data synchronization without sacrificing read-out speed.
Data Source
AI summary
Techniques are described for implementing read-out architectures to support high-speed serialized read-out of a large number of digital bit values, such as for high-resolution pixel conversions in CMOS image sensor applications. For example, outputs from a large number of digital data sources (e.g., counters) are coupled with transmission gates of the read-out architecture, and the transmission gates are sequentially enabled, thereby shifting in bit data from the data sources one at a time. The transmission gates are grouped into gate groups. For each gate group, embodiments seek balance total path delay across the gate groups by controlling clock and data path delays to be inversely related, and ensuring that total path delays for all gate groups are within a single clock period. Some embodiments include a partitioned bus for further gate group-level control over the path delay and data bus capacitance.