Multi-frequency resonant clock mesh power reduction
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Solution Overview
Problem
High-performance VLSI chips face challenges in power consumption and heat generation due to increasing clock rates and densities, with clock distribution networks consuming a significant portion of the chip's power and experiencing signal delays and skew, while existing resonant clock solutions only operate at a single frequency, neglecting power savings in data-path logic.
Innovation Solution
A resonant clock mesh that utilizes inductor-capacitor (LC) tanks selectively attached through NMOS pass transistors and a tri-state clock driver, enabling operation at multiple frequencies by adjusting the number of enabled LC tanks to change resonant frequency, with the driver capable of being disabled for maximum power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resonant clock networks are used to reduce power consumption, then power efficiency is improved, but the system can only operate at a single resonant frequency
Solution Approach 1:
The patent implements dynamic frequency scaling by making the resonant clock network adaptable to multiple frequencies. The system can dynamically switch between different operating frequencies (e.g., 1 GHz, 1.75 GHz, 2.67 GHz) based on performance requirements, transforming a static single-frequency system into a dynamic multi-frequency system that optimizes both power consumption and performance.
Solution Approach 2:
The patent changes the resonant frequency parameter of the clock network by adjusting the number of enabled LC tanks. By varying the effective inductance through selective activation of different LC tank combinations, the system achieves multiple resonant frequencies while maintaining power efficiency benefits across different operating conditions.
2Speed
If higher clock rates are used to increase performance, then processing speed is improved, but power consumption and heat generation increase
Solution Approach 1:
The patent employs resonant oscillation where LC tanks periodically store and release energy at their natural resonant frequency. This periodic energy exchange allows the clock network to sustain high-frequency operation with minimal power input, as the resonant structures naturally oscillate and require only small periodic energy injections to maintain operation at higher clock rates.
Solution Approach 2:
The system adjusts the resonant frequency parameter to match different performance requirements. By changing the effective inductance through selective LC tank activation, the system can operate at higher clock rates when performance is critical while maintaining power efficiency through resonant operation, rather than using non-resonant clocking that would consume significantly more power at the same frequency.
3Speed
If more LC tanks are enabled to achieve higher frequencies, then clock rate is improved, but the number of components and complexity increases
Solution Approach 1:
The patent divides the clock distribution network into multiple segments, each containing LC tanks that can be independently controlled. By segmenting the network and enabling selective activation of different LC tank groups, the system achieves higher frequencies through coordinated operation of multiple segments rather than requiring a single complex high-frequency resonator, thereby managing complexity through modular design.
Solution Approach 2:
The patent designs LC tanks with universal functionality where the same physical LC tank structure serves multiple frequency purposes. Each LC tank can be individually enabled or disabled, and different combinations of tanks produce different effective inductances, allowing the same hardware components to support multiple operating frequencies without requiring dedicated components for each frequency mode.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables dynamic frequency scaling, reducing power consumption in both clock and data-path logic by recycling energy and allowing operation at various frequencies, thereby improving performance and reducing heat generation.
Implementation Method 1
resonant clock meshes that resonate at multiple frequencies
Implementation Method 2
inductor-capacitor (LC) tank attached to the clock mesh
Data Source
AI summary
Power-efficient resonant clock meshes and multiple frequency resonant clock distribution networks.