Printed Wiring Board Ground Segmentation for EMI Reduction
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Solution Overview
Problem
Printed wiring boards in electronic equipment face interference issues between baseband and high-frequency blocks due to noise contamination and radiation, leading to signal quality deterioration and spurious noise, which existing shielding and ground separation methods fail to adequately address.
Innovation Solution
A printed wiring board design featuring a signal plane with baseband and high-frequency blocks connected via a transmission line, where a ground plane with a first and second ground portion are coupled through a low-impedance coupling portion, allowing for a minimal return path and reducing mutual interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the baseband block and high-frequency block are placed on the same printed wiring board, then device integration is improved, but electromagnetic interference between blocks increases
Solution Approach 1:
The ground plane is segmented into a first ground portion beneath the baseband block and a second ground portion beneath the high-frequency block, physically separating the ground regions to prevent electromagnetic coupling between the two functional blocks while maintaining overall device integration
Solution Approach 2:
Different ground portions are provided for different functional blocks, with each ground portion optimized for its specific block's requirements, allowing local electromagnetic environment optimization without compromising overall integration
2Ease of manufacture
If a common ground plane is used for both blocks, then manufacturing simplicity is improved, but noise contamination between blocks occurs
Solution Approach 1:
The ground plane is divided into separate first and second ground portions for the baseband and high-frequency blocks respectively, preventing noise contamination through ground isolation while maintaining a relatively simple manufacturing process
Solution Approach 2:
A coupling portion acts as an intermediary element to connect the first and second ground portions, providing a controlled impedance path that allows necessary signal return currents while blocking noise contamination between blocks
3Object-generated harmful factors
If the ground plane is separated into first and second ground portions, then noise isolation is improved, but return path for interface signals deteriorates
Solution Approach 1:
A coupling portion is introduced as an intermediary element to connect the separated first and second ground portions, providing a dedicated low-impedance path for return currents of interface signals while maintaining noise isolation between the main ground regions
Solution Approach 2:
The first and second ground portions are electrically connected through the coupling portion to form a unified reference potential for interface signals, ensuring reliable return paths while maintaining physical separation for noise isolation
4Object-generated harmful factors
If a shield case is provided for the high-frequency portion, then radiation noise is reduced, but device complexity increases
Solution Approach 1:
The ground plane is extracted and separated into distinct first and second ground portions for the baseband and high-frequency blocks, creating inherent electromagnetic isolation that reduces radiation noise without requiring additional shield case structures
Solution Approach 2:
The separated ground portions serve multiple functions: providing reference potentials for respective blocks, isolating electromagnetic noise, and enabling controlled impedance paths, thereby replacing the need for separate shield cases
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 design stabilizes the interface function, prevents noise contamination, reduces spurious noise, and minimizes electromagnetic interference, thereby maintaining signal quality and preventing sensitivity suppression.
Implementation Method 1
the first ground portion and the second ground portion are coupled to each other through a coupling portion provided therebetween which has a low impedance with respect to a signal of a specific frequency region
Data Source
AI summary
A printed wiring board, comprising a signal plane having a baseband block for processing a baseband signal and a high-frequency block for processing a high-frequency signal which is obtained by converting the baseband signal, and a ground plane opposing to the signal plane. The baseband block and the high-frequency block are connected through a transmission line for transmitting a signal of a specific frequency region. The ground plane is provided with a first ground portion and a second ground portion, the first ground portion being provided at an area opposing to the baseband block, the second ground portion being provided at an area opposing to the high-frequency block. The first ground portion and the second ground portion are coupled to each other through a coupling portion provided therebetween which has a low impedance with respect to the signal of the specific frequency region.