Defected Ground Structure With Resistive Perimeter for EMI Suppression
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Solution Overview
Problem
Existing solutions for minimizing electromagnetic interference (EMI) radiation from circuit boards, such as discrete EMI chokes and mechanical shielding, are inadequate for high-frequency communications, and existing defected ground structures only reflect EMI back to its source without adequate absorption.
Innovation Solution
A defected ground structure with a resistive material along its perimeter is implemented within the circuit board to absorb and suppress EMI, reducing radiation from plated vias and ground vias by optimizing the size, shape, and location of the void in relation to these elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing defected ground structures are used to contain EMI within the circuit board, then EMI reflection back to source is reduced, but EMI absorption is inadequate and radiation suppression is insufficient
Solution Approach 1:
The patent combines resistive material with the defected ground structure to create a composite EMI suppression system. The resistive material is positioned adjacent to the void in the ground plane, forming a composite structure that simultaneously provides both reflection and absorption mechanisms for EMI containment.
Solution Approach 2:
The resistive material is strategically placed only in specific locations adjacent to the void rather than uniformly across the entire ground plane. This localized placement optimizes EMI absorption at critical radiation points while maintaining overall system performance and minimizing material usage.
2Object-affected harmful factors
If discrete EMI chokes and mechanical shielding are used to shield other parts from EMI, then EMI protection is provided, but they are inadequate for high-frequency communications
Solution Approach 1:
The patent extracts the EMI suppression function from traditional discrete components (EMI chokes and mechanical shields) and integrates it directly into the circuit board's ground plane structure. This integrated defected ground structure with resistive material provides high-frequency EMI protection without requiring separate external components.
Solution Approach 2:
The patent replaces mechanical shielding approaches with an electromagnetic-based defected ground structure that uses controlled impedance and resistive materials to suppress EMI. This substitution enables effective high-frequency protection where mechanical shields become inadequate.
3Reliability
If plated vias and ground vias are used to connect components, then electrical connectivity is achieved, but they act as antennas that radiate EMI outwards from the circuit board
Solution Approach 1:
The resistive material acts as an intermediary element positioned between the void and the radiating vias. It absorbs EMI energy before it can radiate outward, mediating between the electrical connectivity function of the vias and the harmful radiation they generate.
Solution Approach 2:
The patent converts the harmful EMI radiation from vias into beneficial absorbed energy through the resistive material. The resistive material dissipates the EMI energy as heat, transforming the harmful radiated energy into a contained and harmless form.
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
The solution effectively minimizes EMI radiation across a wider frequency band, improving EMI suppression and reducing the amount of EMI reflected back to its source, thereby enhancing the performance of electronic devices by containing EMI within the circuit board.
Implementation Method 1
a defected ground structure with a resistive material along its perimeter is implemented within the circuit board to absorb and suppress EMI
Implementation Method 2
existing defected ground structures only reflect EMI back to its source without adequate absorption
Data Source
AI summary
A multiple-layer circuit board has a signaling layer, an exterior layer, and a ground layer. A pair of differential signal lines implemented as strip lines are within the signaling layer, and propagate electromagnetic interference (EMI) along the signaling layer. An element conductively extends inwards from the exterior layer. A void of a defected ground structure within the ground layer has a size, shape, and a location in relation to the element to suppress the EMI propagated by the strip lines. A resistive material of the defected ground structure along a perimeter of the void improves suppression of the EMI propagated by the strip lines, via the resistive material absorbing the EMI.