Power Gating Stitching Order Optimization for Leakage Reduction
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Solution Overview
Problem
In integrated circuit (IC) design, existing power gating techniques face challenges in reducing leakage power consumption due to long distances between power gating cells, leading to increased routing complexity and resource consumption when optimizing stitching orders.
Innovation Solution
A method is introduced to optimize the stitching order of power gating cells by separating them with a circuit block, using a scan re-order tool to generate a placement file and swapping scan cells with power gating cells, thereby reducing the number of neighboring power gating cells and inserting buffers when necessary to maintain control signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power gating cells are placed far apart to reduce leakage power, then power gating effectiveness is improved, but routing complexity and resource consumption increase
Solution Approach 1:
The patent introduces scan cells as intermediary elements between power gating cells. These scan cells act as mediators that can be reordered to optimize the stitching order, reducing the need for long routing connections between power gating cells while maintaining their spatial separation for effective leakage power reduction.
Solution Approach 2:
The patent applies dynamic reordering of scan cells based on the placement of power gating cells. The stitching order is not fixed but dynamically optimized by analyzing the spatial distribution of power gating cells and reordering scan cells to minimize routing complexity while maintaining the beneficial separation of power gating cells.
2Loss of energy
If power gating cells are placed far apart to reduce leakage power, then power gating effectiveness is improved, but the number of buffers required increases
Solution Approach 1:
Scan cells serve as intermediary elements that can be strategically reordered to reduce the number of buffers needed. By reordering scan cells to group power gating cells with similar spatial characteristics, the patent reduces the number of long-distance connections that would otherwise require buffer insertion.
Solution Approach 2:
The patent performs preliminary reordering of scan cells before final routing is established. This preliminary action optimizes the stitching order to minimize the number of buffers required, preventing the need for buffer insertion later in the design process.
3Ease of manufacture
If traditional stitching order is used based on cell names or insertion sequence, then implementation simplicity is maintained, but routing efficiency and resource optimization are reduced
Solution Approach 1:
The patent transitions from a static stitching order (based on cell names or insertion sequence) to a dynamic stitching order that is optimized based on the actual spatial placement of power gating cells. This dynamic approach improves routing efficiency by minimizing connection lengths while maintaining reasonable implementation complexity through automated reordering algorithms.
Solution Approach 2:
The patent changes the parameter used for determining stitching order from cell names or insertion sequence to spatial coordinates and distance metrics. By using placement-based parameters, the stitching order can be optimized to reduce routing length and resource consumption while still being implementable through automated tools.
Data Source
AI summary
Aspects of the disclosure provide a method to design integrated circuit (IC) using power gating techniques. The method includes determining a placement of a plurality of power gating cells and at least a circuit block in an IC layout. On the IC layout, a first set of power gating cells and a second set of power gating cells are separated by the circuit block with a distance longer than a threshold. Further, the method includes optimizing a stitching order of the power gating cells for the placement to reduce a number of instances that the power gating cells in the first set and the power gating cells in the second set are neighboring power gating cells in the stitching order.