PCB Electromagnetic Bandgap Structure for LiP RF Channel Isolation
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Solution Overview
Problem
In Launcher in Package (LiP) devices, the stacking of components results in gaps between the printed circuit board (PCB) and the antenna structure, leading to cross-coupling between internal RF channels, which degrades the quality of RF signals, especially in Multiple-Input Multiple-Output (MIMO) communications.
Innovation Solution
An electromagnetic bandgap (EBG) structure is printed on the PCB surface facing the antenna structure, comprising a plurality of EBG elements arranged in a periodic pattern to border through-holes or metallic vias, acting as a barrier to prevent energy leakage between internal RF channels, thereby reducing cross-coupling and enhancing signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If components are stacked to form LiP devices, then integration is improved and PCB system cost is reduced, but gaps are formed between PCB and antenna structure leading to cross-coupling between RF channels
Solution Approach 1:
An electromagnetic bandgap (EBG) structure is introduced as an intermediary element between the antenna structure and the PCB. This EBG structure acts as a mediator that prevents harmful electromagnetic coupling between RF channels while maintaining the integrated LiP device architecture. The EBG structure is printed on the PCB surface facing the antenna structure, creating a barrier that isolates adjacent RF channels without requiring additional stacked layers.
2Ease of manufacture
If gaps are formed between PCB and antenna structure, then manufacturing is simplified, but cross-coupling between internal RF channels increases degrading signal quality
Solution Approach 1:
The EBG structure is applied locally on the PCB surface at specific locations where RF channels are adjacent to each other. Rather than requiring uniform treatment across the entire device or adding global structural layers, the EBG elements are selectively placed in regions where cross-coupling occurs, providing targeted isolation while maintaining manufacturing simplicity and preserving signal quality in affected areas.
3Reliability
If EBG structure is added to reduce cross-coupling, then signal quality is improved, but device complexity increases with extra layer of milled EBG material
Solution Approach 1:
The EBG structure is merged with the existing PCB structure by printing it directly on the PCB surface using standard PCB fabrication techniques. This integration combines the EBG functionality with the PCB manufacturing process, eliminating the need for separate milled EBG layers or additional stacked components. The result is a unified structure that reduces device complexity while maintaining the cross-coupling isolation benefits.
4Device complexity
If EBG structure is printed on PCB surface, then manufacturing complexity is reduced without extra milled layers, but manufacturing precision requirements increase
Solution Approach 1:
The EBG structure leverages the existing PCB manufacturing capabilities and processes to create the required pattern. By using standard PCB printing and etching techniques, the EBG structure self-generates through conventional fabrication steps without requiring additional specialized equipment or post-processing operations. This approach trades minimal precision requirements for significant reductions in manufacturing complexity.
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 EBG structure effectively isolates RF signals, reducing cross-coupling between internal RF channels and improving the transmission and reception signal quality of LiP devices by containing energy within specific frequency bands, such as 77 GHz, without the need for an extra layer of milled EBG material.
Implementation Method 1
an electromagnetic bandgap (EBG) structure on the second surface, the EBG structure comprising a plurality of EBG elements
Data Source
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AI summary
A Launcher in Package (LiP) device for wireless communications, e.g., radar communications at 77 GHz, includes a printed circuit board (PCB) arranged between a radio frequency (RF) chip package and a radiating antenna structure. The PCB include an electromagnetic bandgap (EBG) structure including a plurality of EBG elements printed in a periodic pattern on the side of the PCB facing the radiating antenna structure. The plurality of EBG elements border at least one side of an RF channel through the PCB that couples an antenna element of the radiating antenna structure with a corresponding RF launcher in the RF chip package.