Directional Coupler Impedance Transforming Attenuator
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Solution Overview
Problem
The design and fabrication of miniaturized directional couplers face challenges due to limitations in accuracy and control over transmission line dimensions, material properties, and substrate consistency, which hinder the achievement of high directivity and compact size while meeting impedance matching requirements.
Innovation Solution
Incorporating an impedance matching and impedance transforming attenuator that adjusts the reference impedance to a transformed impedance value, allowing for a reduced product of even and odd mode impedances, enabling wider transmission lines for easier fabrication and miniaturization while maintaining high directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If transmission line dimensions are reduced for miniaturization, then the size of the directional coupler is reduced, but the manufacturing precision and fabrication accuracy deteriorate due to limitations in controlling transmission line dimensions and material properties
Solution Approach 1:
An impedance transforming attenuator is introduced as an intermediary component between the transmission lines and the load. This attenuator transforms the impedance seen by the transmission lines, allowing the use of wider, easier-to-fabricate transmission lines while maintaining the required impedance matching and directivity performance. The attenuator acts as a mediator that decouples the strict impedance requirements from the physical transmission line dimensions.
2Volume of moving object
If transmission line dimensions are reduced for miniaturization, then the size of the directional coupler is reduced, but the directivity performance deteriorates due to substrate limitations and material property variations
Solution Approach 1:
The impedance transforming attenuator serves as an intermediary that compensates for variations in substrate properties and material characteristics. By transforming the impedance, it ensures consistent directivity performance regardless of substrate limitations or manufacturing tolerances, allowing miniaturization without sacrificing reliability.
3Ease of manufacture
If standard impedance matching is used without transformation, then the impedance matching is straightforward, but the transmission lines must be narrower and more difficult to fabricate with precision
Solution Approach 1:
The impedance transforming attenuator is positioned as an intermediary component that handles the impedance transformation function. This allows the transmission lines to be designed with wider dimensions for easier fabrication, while the attenuator compensates to achieve the required impedance matching, thereby reducing the precision requirements for transmission line manufacturing.
4Ease of manufacture
If the product of even mode impedance and odd mode impedance is kept at standard reference impedance squared, then the impedance matching is standard, but the transmission lines cannot be widened for easier fabrication
Solution Approach 1:
The impedance transforming attenuator is introduced as an intermediary device that handles the impedance transformation function separately from the transmission lines. This allows the transmission lines to be optimized for ease of fabrication with wider dimensions, while the attenuator manages the impedance transformation complexity, effectively decoupling these two design considerations.
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 enhances the fabrication precision and miniaturization of directional couplers, improving their directivity and coupling ratio while reducing the impact of substrate limitations, making them more suitable for compact RF front-end circuits.
Implementation Method 1
The pair of coupled transmission lines 55 are located in close proximity to each other so that they are electromagnetically coupled to each other
Implementation Method 2
an impedance matching and impedance transforming attenuator with one terminal thereof connected to third RF port 53 and with another terminal thereof forming a fifth RF port 57. The impedance matching and impedance transforming attenuator provides a level of attenuation and, moreover, transforms a reference impedance value Z0 to a transformed impedance value ZP3
Data Source
AI summary
The present invention provides a compact weakly coupled directional coupler combined with an integrated impedance transformation and matching circuit where the impedance transformation and matching circuit facilitates the fabrication of a highly miniaturized directional coupler with optimum electrical performance where the physical dimensions of the coupled transmission lines fall inside the constraints of the fabrication process.