High-Frequency PCB Transmission Layout Without Coaxial Cables
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Solution Overview
Problem
Existing high-frequency transmission systems in portable electronic devices face challenges with noise transmission and material costs due to the use of coaxial cables, which also incur higher assembly costs and defect rates in narrow internal spaces.
Innovation Solution
The implementation of a flexible printed circuit board (FPCB) with integrated rigid PCBs to replace coaxial cables, allowing for noiseless high-frequency signal transmission without affecting other modules, reducing material costs, and optimizing space usage in portable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coaxial cables are used for high-frequency transmission, then signal transmission quality is improved, but material cost and assembly cost increase
Solution Approach 1:
The patent replaces expensive coaxial cables with inexpensive PCB-trace-based transmission lines. The transmission function is integrated directly into the PCB structure using standard copper traces and vias, eliminating the need for separate coaxial cable components and their associated connectors, thereby significantly reducing material and assembly costs while maintaining high-frequency signal transmission capability.
Solution Approach 2:
The patent merges the transmission line function with the PCB structure itself. The signal transmission path is formed by copper traces and vias that are part of the PCB manufacturing process, combining the circuit board and transmission line into a single integrated structure, thus eliminating separate coaxial cable assemblies and reducing overall system complexity.
2Reliability
If coaxial cables with small connectors are used, then high-frequency signal transmission is achieved, but defect rate increases due to narrow internal spaces
Solution Approach 1:
The patent integrates the transmission line directly into the PCB structure using copper traces and vias that are formed during standard PCB manufacturing processes. This eliminates the need for separate coaxial cable assemblies and their small connectors, thereby avoiding assembly defects in narrow internal spaces while maintaining high-frequency signal transmission capability.
Solution Approach 2:
The patent replaces the mechanical coaxial cable connector system with an electrical trace-based transmission line on the PCB. The connection is achieved through soldered pads and vias rather than mechanical plug-and-play connectors, eliminating assembly complexity and defect risks associated with small connectors in confined spaces.
3Ease of manufacture
If FPCB is used to replace coaxial cable, then material cost is reduced, but line loss increases
Solution Approach 1:
The patent applies different PCB structure types in different sections of the transmission path. Rigid PCB sections with controlled impedance and optimized trace geometry are used in areas requiring low line loss, while flexible PCB sections are used where bending and flexibility are needed. This localized optimization maintains low line loss while preserving the cost benefits of FPCB technology.
Solution Approach 2:
The patent creates a composite PCB structure combining rigid and flexible PCB sections. The rigid portions provide stable electrical characteristics and low loss for high-frequency signals, while the flexible portions provide mechanical adaptability. This composite structure mitigates the line loss issue of pure FPCB while maintaining cost advantages over coaxial cables.
4Loss of energy
If rigid PCB is disposed between FPCB transmission lines, then line loss is reduced, but device complexity increases
Solution Approach 1:
The patent merges the rigid and flexible PCB sections into a single integrated PCB assembly. The rigid portion serves as both the structural support and the low-loss transmission medium, while the flexible portion provides connectivity and adaptability. This integration reduces the number of separate components and assembly steps, thereby reducing device complexity despite the multi-section structure.
Data Source
AI summary
Disclosed is a portable communication device including a housing, a first printed circuit board (PCB) disposed in the housing, a wireless communication circuit mounted on the first PCB, and a second PCB including a connection part connected with the first PCB, a first PCB portion extended from the connection part and having greater flexibility than the connection part, a second PCB portion extended from the first PCB portion and having less flexibility than the first PCB portion, a third PCB portion extended from the second PCB portion and having greater flexibility than the second PCB portion, a fourth PCB portion extended from the third PCB portion and having less flexibility than the first PCB portion, a signal line extended to the connection part along the first, second, third, and fourth PCB portions, and vias arranged in at least a partial area of the second PCB portion or the fourth PCB portion, wherein a portion of the signal line is located between some of the vias.