Multi-Track Standard Cell Logic Blocks With Mixed Cell Heights
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Solution Overview
Problem
Conventional cell libraries for ASIC design typically use standard cells of the same height, limiting design flexibility and optimization in logic blocks, as they do not allow for rows of standard cells with varying track heights, which can restrict performance, power efficiency, and area optimization.
Innovation Solution
A cell library and method for designing logic blocks that include rows of standard cells with different track heights, where each standard cell is designed to fit within a row of a fixed track height, ensuring aligned power rails and compatible footprints, allowing for mixed cell heights and track heights in a single row to enhance performance, power efficiency, and area optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard cells of the same height are used in conventional cell libraries, then manufacturing simplicity and ease of placement are maintained, but design flexibility and optimization capability are limited
Solution Approach 1:
The cell library is segmented into multiple groups, each containing standard cells of a specific height. This segmentation allows the design tool to selectively choose from different cell height groups based on optimization requirements, thereby increasing design flexibility without overwhelming complexity in the overall library structure.
Solution Approach 2:
The cell library transitions from a static structure with uniform cell heights to a dynamic structure where cell heights vary by group. The placement tool dynamically selects appropriate cell height groups during the placement process, enabling adaptation to different design requirements while maintaining systematic organization.
2Productivity
If standard cells with different heights are allowed in a cell library, then performance and area optimization are improved, but placement complexity and routing alignment difficulty increase
Solution Approach 1:
Different regions of the logic block can utilize standard cells of different heights appropriate to their specific functional requirements. Power rail alignment is maintained locally within each placement region, allowing optimization at the local level without compromising global routing integrity.
Solution Approach 2:
The cell height parameter is changed and varied across different cell groups rather than being fixed. This parameter change enables placement optimization by allowing selection of cells with heights matched to specific logic block requirements, improving placement efficiency while the systematic grouping manages the complexity.
3Area of stationary object
If mixed cell heights are used in a single row, then area optimization and power efficiency are enhanced, but power rail alignment and routing compatibility become more difficult
Solution Approach 1:
The power rail alignment is maintained at the same horizontal level (equipotential line) across cells of different heights within a row. By ensuring that power rails remain aligned horizontally despite cell height variations, the invention achieves area optimization while preserving manufacturing precision and routing compatibility.
Solution Approach 2:
The solution moves the variation to the vertical dimension (cell height) while maintaining horizontal alignment (power rail position). This dimensional separation allows cells to have different heights without compromising power rail alignment, enabling area optimization while maintaining manufacturing precision.
4Adaptability or versatility
If a cell library includes multiple cell height groups, then design optimization capability is improved, but tool complexity and synthesis time increase
Solution Approach 1:
Standard cells are pre-categorized into groups by height during library construction, and power rail positions are pre-determined for each group. This preliminary organization allows the placement tool to quickly select appropriate cells without performing complex real-time calculations, thereby improving optimization capability while minimizing additional synthesis time.
Solution Approach 2:
The cell library structure is designed to be universally applicable across different logic block types and design requirements. By creating a systematic multi-height cell library with standardized power rail alignment, the system achieves broad optimization capability across various designs while using efficient selection algorithms that minimize synthesis time overhead.
Data Source
AI summary
A logic block, a cell library, a method of designing a logic block and an ASIC including the logic block. The invention provides a logic block including rows of standard cells having different track heights. In one embodiment, the invention provides a logic block including: (1) a first row of standard cells having a first track height and (2) a second row of standard cells adjacent to the first row and having a second track height that differs from the first track height.