MTCMOS Circuit Cell Wiring Segmentation for IR Drop Reduction
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Solution Overview
Problem
Existing semiconductor integrated circuits face inefficiencies due to unnecessarily thick wirings for branch lines in MTCMOS and non-MTCMOS-based circuit cells, leading to increased cell area and reduced layout versatility.
Innovation Solution
The implementation of a semiconductor integrated circuit design where always-on circuit cells are connected directly to the main line without a power switch, reducing the need for thick wirings and allowing for a more efficient layout by minimizing source current flow through shared branch lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick wirings are used for the second branch line to reduce IR drop and electromigration resistance, then reliability is improved, but the circuit cell size increases
Solution Approach 1:
The patent segments the always-on circuit cells into two groups: those connected via the second branch line and those connected via individual connection lines. This segmentation allows the second branch line to serve fewer cells, reducing its current load and enabling thinner wiring while maintaining reliability for the segmented group.
Solution Approach 2:
The patent introduces individual connection lines as intermediary pathways for always-on circuit cells. These connection lines act as mediators that bypass the second branch line, distributing current more evenly and reducing the burden on the shared branch line, thereby allowing reduced wiring thickness.
2Reliability
If thick wirings are used for the first and second branch lines to ensure versatility and reduce IR drop, then operational reliability is improved, but layout efficiency decreases
Solution Approach 1:
The patent applies local quality by providing different wiring configurations for different circuit cells based on their specific needs. Always-on circuit cells near the main line use individual connection lines with lower current load, while other cells use the second branch line. This localized differentiation optimizes both reliability and layout efficiency for each cell's specific context.
3Device complexity
If the second branch line is used for multiple always-on circuit cells, then device complexity is reduced, but IR drop increases due to higher source current flow
Solution Approach 1:
The patent segments the always-on circuit cells into two groups: those connected via the second branch line and those connected via individual connection lines. This segmentation divides the total source current into smaller portions, reducing the current load on the second branch line and thereby minimizing IR drop while maintaining reasonable device complexity.
Solution Approach 2:
The patent applies partial action by having only some always-on circuit cells use the shared second branch line, while others use individual connection lines. This partial use of the branch line reduces the total current flow through it, decreasing IR drop without completely eliminating the benefits of shared wiring for all cells.
Data Source
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AI summary
Disclosed herein is a semiconductor integrated circuit including: a cell layout region (A1) including circuit cells (10) subject to power control the supply and interruption of power to which is controlled by a power switch (20), and always-on circuit cell groups (50) which are always powered after the activation; a main line (PL1) laid out in the cell layout region (A1) and applied with a source (VDD) or reference (VSS) voltage; and first and second branch lines (BL2) which branch from the main line (PL1) in the cell layout region (A1).