Modulated Termination for EMI Reduction
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Solution Overview
Problem
Conventional methods are inadequate in controlling electromagnetic interference (EMI) at higher processor clock frequencies due to the smaller wavelengths of electromagnetic radiation, which are difficult to contain using conventional shielding methods.
Innovation Solution
The method involves continuously varying the electrical impedance at termination locations between metal substructures that radiate electromagnetic noise, causing a continuous change in the amplitude of the noise at specific frequencies, thereby reducing the average measured emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shielding methods are used to contain electromagnetic radiation, then shielding effectiveness is improved, but the method becomes ineffective at higher frequencies due to smaller wavelengths
Solution Approach 1:
The patent applies dynamics by making the termination impedance variable rather than fixed. The impedance is continuously varied over time to change the resonant characteristics of metal substructures, preventing them from maintaining consistent radiating patterns at higher frequencies. This dynamic adjustment allows the shielding system to adapt to different frequency conditions, resolving the contradiction between shielding effectiveness and frequency range applicability.
Solution Approach 2:
The patent changes the electrical parameter of termination impedance to control electromagnetic radiation. By varying the impedance value, the system alters the resonant frequency and radiation characteristics of metal substructures. This parameter change enables effective shielding at higher frequencies where conventional fixed shielding fails, addressing the adaptability issue while maintaining shielding effectiveness.
2Object-generated harmful factors
If Faraday shields are added around metal substructures, then electromagnetic radiation is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the shielding function from the physical Faraday shield structure and relocates it to the electrical termination points. Instead of adding external shielding structures around metal substructures, the solution modifies the electrical characteristics at termination locations. This extraction eliminates the need for complex physical shields while achieving the same electromagnetic radiation control, resolving the contradiction between radiation reduction and device complexity.
Solution Approach 2:
The patent replaces the mechanical/physical shielding approach (Faraday shields) with an electrical control approach (variable impedance termination). By substituting the mechanical shielding system with an electrical system that controls radiation through impedance variation, the solution reduces structural complexity while maintaining effectiveness in reducing electromagnetic radiation.
3Reliability
If aperture sizes in metal enclosures are reduced to improve shielding, then high-frequency shielding is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces variable impedance termination as an intermediary control mechanism between the signal source and the metal substructures. This intermediary allows control of electromagnetic radiation at the source level rather than relying on physical aperture restrictions. By using this intermediary, the system achieves high-frequency shielding effectiveness without the need for precisely controlled small apertures, resolving the contradiction between shielding reliability and manufacturing precision requirements.
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
This approach effectively meets electromagnetic compatibility (EMC) regulatory limits by lowering average emissions, reducing interference with other systems, and is applicable in various electronic devices such as computer systems and printed circuit boards.
Implementation Method 1
An impedance controller is configured to continuously vary the impedance at one or more termination locations between the two metal substructures to continuously vary the amplitude of the electromagnetic noise at a particular frequency of the electromagnetic noise
Data Source
AI summary
The average EMR emissions of an electronic device may be reduced by implementing an electrically-active modulated termination. For example, the impedance may be continuously varied at one or more termination locations between two metal substructures to cause a like variation in the amplitude of each component of the EMR. According to one approach, cyclically varying the electrical impedance with a period of less than the time interval over which the EMR is measured will result in a reduction in the average measured EMR.