Low Ohm Resistors for RF Signal Isolation in Circuit Boards
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Solution Overview
Problem
Current methods for reducing radio frequency (RF) radiation and coupling in circuit assemblies are costly, complex, and often interfere with cooling and access requirements, making them undesirable for efficient RF signal transmission in modern electrical designs.
Innovation Solution
Incorporating low ohm resistors as RF suppression devices along signal lines and at via transitions, electrically connected to a ground plane, to absorb and dissipate RF energy, thereby reducing unwanted emissions and coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal shielding enclosures are used to prevent RF radiation and coupling, then RF isolation is improved, but production cost and assembly complexity increase
Solution Approach 1:
The patent extracts the RF suppression function from complex metal shielding enclosures and implements it through simple low ohm resistors placed directly on the circuit board at via transitions and signal line intersections. This removes the need for bulky metal cans while maintaining RF isolation through resistive damping of unwanted signals.
Solution Approach 2:
The patent replaces expensive metal shielding enclosures with inexpensive low ohm resistors that can be easily soldered onto the circuit board. These simple passive components provide the necessary RF suppression without the high cost and complexity of metal shielding structures.
2Reliability
If metal shielding enclosures are used to prevent RF radiation, then RF coupling is reduced, but cooling and access requirements are interfered with
Solution Approach 1:
The patent removes metal shielding enclosures that physically blocked access and cooling paths, replacing their RF suppression function with low ohm resistors that do not obstruct physical access or thermal management pathways while still effectively reducing RF coupling.
3Reliability
If grounded coplanar waveguides are used for RF signal transmission, then RF isolation is improved, but via transitions are required which increase cost and radiation
Solution Approach 1:
The patent converts the potentially harmful RF radiation from via transitions into beneficial suppressed signals by placing low ohm resistors directly at the via transition locations. These resistors dampen the unwanted RF energy that would otherwise radiate, turning a harmful effect into a controlled dissipation of energy.
Solution Approach 2:
The patent applies RF suppression locally at specific problem areas such as via transitions and signal line intersections using low ohm resistors, rather than requiring global changes to the transmission line structure like grounded coplanar waveguides. This targeted approach suppresses radiation at its source without altering the overall signal path architecture.
4Reliability
If signal isolation vias and conductive paste are used to isolate RF signal lines, then RF coupling is reduced, but design and manufacturing complexity increase
Solution Approach 1:
The patent extracts the RF suppression function from complex multi-layer isolation structures involving isolation vias and conductive paste, replacing them with simple low ohm resistors that can be easily placed and soldered onto the circuit board using standard manufacturing processes.
Solution Approach 2:
The patent replaces expensive and complex isolation structures with inexpensive low ohm resistors that simplify both design and manufacturing. These resistors can be applied using standard surface mount technology without requiring specialized processes for creating isolation vias or applying conductive paste.
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 approach provides effective and economical RF signal isolation, reducing RF oscillations and coupling while allowing for closer signal line spacing and simplified circuit designs, lowering production costs and enhancing reliability.
Implementation Method 1
Incorporating low ohm resistors as RF suppression devices along signal lines and at via transitions, electrically connected to a ground plane, to absorb and dissipate RF energy
Data Source
AI summary
Systems and methods for isolating radio frequency (RF) signals in high frequency circuit assemblies, including but not limited to 5G communication systems, are provided. The circuit assemblies include an RF suppression structure, which can be in the form of a low ohm resistor, that extends across a transmission line, and that has contacts that are electrically joined to a ground plane. Alternatively or in addition, the circuit assemblies include a low ohm resistor that extends over a transition between a signal via and an end of a transmission line, and that has contacts that are electrically joined to a ground plane. A circuit assembly as disclosed herein can further include multiple low ohm resistors spaced apart from one another by a distance that is a fraction of a wavelength of a highest frequency signal carried by the transmission line.