Multilayer PCB EBG Structure for Noise Suppression
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Solution Overview
Problem
High-speed digital systems face challenges in suppressing unwanted electromagnetic interference (EMI) and signal/power integrity issues due to simultaneous switching noise (SSN) in multilayer PCB and package structures, as existing methods like decoupling capacitors and embedded thin film capacitors are limited in frequency band and effectiveness, while EBG structures are difficult to manufacture and affect high-speed signals.
Innovation Solution
A multilayer board design that partially places decoupling capacitors and an electromagnetic bandgap (EBG) structure in specific areas, such as near noise-generating devices or noise-sensitive parts, on power or ground planes to suppress unwanted electromagnetic waves and noise across a wide frequency band from DC to several tens of GHz, minimizing signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If decoupling capacitors are mounted on the PCB to suppress simultaneous switching noise, then signal/power integrity is improved, but production costs increase and PCB space is occupied
Solution Approach 1:
The patent combines the decoupling capacitor function with the EBG structure by integrating capacitive elements into the EBG unit cells. This merging allows the EBG structure to provide both electromagnetic wave suppression and noise decoupling functions simultaneously, eliminating the need for separate decoupling capacitors and reducing PCB space occupation.
Solution Approach 2:
The EBG structure is designed to perform multiple functions: electromagnetic wave suppression, noise reduction, and power decoupling. By making the EBG structure multi-functional, the patent eliminates the need for separate dedicated components for each function, thereby reducing overall device complexity and space requirements while maintaining signal/power integrity.
2Reliability
If decoupling capacitors are mounted on the PCB to suppress simultaneous switching noise, then signal/power integrity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the decoupling capacitor functionality into the EBG structure itself, eliminating the need for separate capacitor mounting processes. This integration simplifies manufacturing by reducing the number of discrete components and assembly steps while maintaining effective noise suppression and signal integrity.
3Object-affected harmful factors
If EBG structure is applied to suppress electromagnetic waves, then EMI is reduced, but high-speed signals are affected
Solution Approach 1:
The patent applies local quality by selectively placing EBG structures only in specific regions where electromagnetic interference is most problematic, such as near noise-generating devices or in critical areas requiring EMI suppression. This localized application minimizes the impact on high-speed signals while maintaining effective EMI reduction in the necessary regions.
Solution Approach 2:
The patent uses partial action by implementing EBG structures only in specific areas rather than across the entire PCB. This partial application allows EMI suppression to be provided where needed while leaving other areas available for high-speed signal transmission without interference, thus balancing EMI reduction with signal integrity.
4Object-affected harmful factors
If EBG structure is applied to suppress electromagnetic waves, then EMI is reduced, but manufacturing difficulty increases
Solution Approach 1:
The patent combines the EBG structure with integrated capacitive elements, creating a unified structure that can be manufactured as a single integrated component. This merging simplifies the manufacturing process by eliminating the need for separate EBG and capacitor fabrication steps, reducing manufacturing difficulty while maintaining effective EMI suppression.
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 suppresses unwanted electromagnetic waves and noise across a broad frequency range, maintaining signal integrity and reducing self-impedance, allowing for the use of unaffected areas as return current paths for high-speed signals, thus enhancing overall system performance.
Implementation Method 1
an electromagnetic wave suppression structure including an electromagnetic bandgap (EBG)
Implementation Method 2
the generated SSN 102 is propagated across the PCB/package by a resonance mode of a parallel conducting plate
Implementation Method 3
mounting a device having a large capacitance, which is called a decoupling capacitor (DeCap), between the power layer and the ground layer
Implementation Method 4
a decoupling capacitor placed on the power plane or the ground plane
Implementation Method 5
a power plane and a ground plane constituting a power distribution network (PDN) are paired and placed inside the multilayer structure, which form a parallel plate waveguide configuration
Data Source
AI summary
A multilayer board for suppressing unwanted electromagnetic waves and noise includes: a power plane and a ground plane constituting a power distribution network; an electromagnetic wave suppression structure placed on the power plane or the ground plane; and a decoupling capacitor placed on the power plane or the ground plane, wherein the electromagnetic wave suppression structure and the decoupling capacitor are placed together.