IC Layout with Mixed-Height Cell Rows for Localized PPA Tuning
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Solution Overview
Problem
Existing integrated circuit (IC) designs face challenges in optimizing power, performance, and area (PPA) across different regions of the IC, as all cells in the layout typically have the same height, limiting the ability to customize performance and power consumption effectively.
Innovation Solution
The approach involves using cells of different heights (tall, short, and unit cells) in an IC layout, allowing for the merging of active regions to create merged cells. This configuration enables the optimization of PPA by placing tall cells for performance improvements and short cells for power and area reductions in specific regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If all cells in the IC layout have the same height, then the layout structure is simple and easy to manufacture, but the ability to optimize power, performance, and area locally is limited
Solution Approach 1:
The IC layout is segmented into multiple cell rows with different heights (first cell row with first height, second cell row with second height). This segmentation allows different regions to have different cell configurations optimized for their specific functions, resolving the contradiction between manufacturing simplicity and localized optimization capability.
Solution Approach 2:
Different cell rows are assigned different heights based on local performance requirements. The first cell row has a first height optimized for its region, while the second cell row has a second height optimized for its region. This local quality approach enables customized PPA optimization in different areas while maintaining overall layout manageability.
2Adaptability or versatility
If cells of different heights are used in the IC layout, then localized PPA optimization is enabled, but the layout complexity increases
Solution Approach 1:
The layout is divided into distinct cell rows with different heights, where each segment can be independently optimized. This segmentation manages complexity by organizing diverse cell configurations into structured rows rather than allowing arbitrary placement throughout the entire layout.
Solution Approach 2:
The layout structure is designed to accommodate multiple cell heights and merged cell configurations within a unified framework. This multi-functional approach allows the same basic layout architecture to support both simple and optimized regions, reducing overall complexity while maintaining optimization flexibility.
3Speed
If tall cells are used for performance improvement, then speed is enhanced in specific regions, but power consumption and area increase
Solution Approach 1:
Tall cells are placed only in specific cell rows where performance is prioritized, while other regions use shorter cells optimized for lower power consumption. This local quality approach ensures that the power-performance tradeoff is optimized for each region's specific requirements rather than applying a uniform configuration throughout.
Solution Approach 2:
The layout is segmented into performance-oriented regions with tall cells and power-efficient regions with short cells. This segmentation allows the system to achieve high speed where needed while minimizing overall power consumption by not using tall cells in regions where performance is less critical.
4Area of stationary object
If short cells are used for area reduction, then chip area and power consumption decrease, but performance speed is reduced
Solution Approach 1:
Short cells are used in regions where area efficiency is the primary concern, while tall cells are used in regions where performance speed is critical. This local quality differentiation ensures that area reduction does not compromise the performance of speed-sensitive circuits.
Solution Approach 2:
The chip area is segmented into regions with different cell heights based on performance requirements. This segmentation allows the majority of the chip to use compact short cells for area efficiency, while dedicating specific segments to tall cells for high-performance functions.
Data Source
AI summary
An IC device includes a plurality of rows of semiconductor devices. The rows are elongated along a first axis and arranged side-by-side along a second axis transverse to the first axis. The rows include a first row having a first height along the second axis, and a second row having a second height along the second axis. The second height is smaller than the first height. Each of the rows includes a first active region of a first conductivity type, and a second active region of a second conductivity type different from the first conductivity type. The second active region is spaced from the first active region along the second axis. Along the second axis, a first width of the first or second active region in the first row is greater than a second width of the first or second active region in the second row.