Backside Power Rail Layout for Lower-Resistance IC Power Gating
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Solution Overview
Problem
As semiconductor integrated circuits (ICs) become smaller and more complex, they face challenges with reduced operating voltages and increased power consumption due to resistance, necessitating effective power management techniques to improve efficiency.
Innovation Solution
The implementation of a header circuit coupled with gated and ungated power circuits, utilizing multiple power rails and transistors to manage voltage supply and reduce resistance, allowing for efficient power switching based on control signals to optimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If operating voltages are reduced to make ICs smaller and more complex, then IC size and complexity are improved, but power consumption increases due to resistance
Solution Approach 1:
The power delivery system is segmented into multiple independent power rails (first power rail, second power rail, third power rail) that can be independently controlled. Each power rail can be selectively activated or deactivated based on circuit requirements, allowing fine-grained power management that reduces overall power consumption while supporting complex IC architectures.
Solution Approach 2:
The patent implements dynamic power control through power gating transistors that can switch power rails on or off in real-time based on operational needs. The power management circuit dynamically adjusts which power rails are active, enabling the system to adapt power consumption to actual computational requirements rather than maintaining constant power delivery.
2Loss of energy
If power gating is used to reduce power consumption, then power consumption is improved, but resistance in power delivery paths increases
Solution Approach 1:
Different power rails are designed with different resistance characteristics tailored to specific circuit regions. The first power rail has different resistance properties than the second and third power rails, allowing each rail to be optimized for its specific function and minimizing resistance-related power losses in critical areas while maintaining gating capabilities where needed.
Solution Approach 2:
The patent introduces a vertical dimension to power delivery by implementing power rails at different levels (first power rail, second power rail, third power rail) rather than relying on a single planar power distribution network. This multi-level approach provides additional pathways for power delivery, reducing the effective resistance through parallel conduction paths while enabling selective gating of individual rails.
Data Source
AI summary
An integrated circuit includes a first power rail on a back-side of a wafer and being configured to supply a first voltage, a header circuit coupled to the first power rail and being configured to supply the first voltage to the first power rail, a second and third power rail on the back-side of the wafer, a fourth power rail on a front-side of the wafer, and a fifth power rail on the back-side of the wafer. The second and third power rail being configured to supply a second voltage. The fourth power rail includes a first set of conductors configured to supply a third voltage to the header circuit. The fifth power rail is configured to supply the third voltage and is separated from the first power rail in a first and second direction, and is separated from the second and third power rail in the first direction.