Clock Tree Frequency Reduction for Lower IC Power

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Solution Overview

Problem

The clock tree in integrated circuits consumes a significant portion of the total power due to its high switching rate and large capacitive loads, contributing to approximately one-third of the chip's power consumption.

Innovation Solution

A clock network that reduces the operation frequency of the clock signal by half using a reduction circuit and restores it to the desired frequency using restoration circuits before delivery to destination components, thereby reducing power consumption while maintaining performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the clock tree operates at high frequency to meet performance requirements, then the processing speed is improved, but the power consumption increases significantly

Engineering Contradiction:

Improveclock frequencyVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The clock network is segmented into multiple domains with different frequency requirements. Each domain operates at its own optimized frequency rather than a single high frequency throughout the entire system, reducing overall power consumption while maintaining high-speed operation where needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clock frequency is made dynamic and adjustable based on operational requirements. The system can switch between different frequency modes (e.g., high frequency for performance-critical paths, low frequency for non-critical paths) to optimize the power-performance tradeoff in real-time.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the clock tree switches at maximum rate to maintain signal integrity, then the signal quality is improved, but the power consumption increases

Engineering Contradiction:

Improvesignal integrityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The clock signal transitions from continuous maximum-rate switching to periodic action where clocks are enabled only when needed. Gating mechanisms allow the clock to be turned off during idle periods or in non-critical paths, maintaining signal integrity when active while reducing power consumption through periodic rather than continuous operation.

Inventive Principle:

Principle #19Periodic action

3Area of stationary object

If the clock tree drives large capacitive loads to reach all destination components, then the coverage is improved, but the power consumption increases

Engineering Contradiction:

Improveclock distribution coverageVSAvoidpower consumption

Core Design Contradiction:

Area of stationary objectVSUse of energy by moving object

Solution Approach 1:

Different regions of the clock tree are assigned different quality characteristics and frequency levels based on their specific requirements. Critical paths receive high-frequency clocks with full driving capability, while non-critical regions operate at lower frequencies with reduced driving strength, optimizing the balance between coverage and power consumption.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12368442B2Low power clock network

Publication Date: 2025.07.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A first clock signal is generated from a reference clock signal. A first frequency associated with the first clock signal is less than a reference clock frequency associated with the reference clock signal. The first clock signal is propagated towards a first component of an integrated circuit through a clock tree. A second clock signal having a second frequency is generated from the first clock signal at a terminal point of the clock tree. The second clock signal is provided to the first component.