Transmission Line Impedance Sections for RF End Reflection Control
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Solution Overview
Problem
Existing radio frequency signal transmission lines experience impedance mismatching near the end portions due to variations in impedance at connectors or via-hole conductors, leading to potential reflection and insertion loss issues.
Innovation Solution
The transmission line design includes specific sections with varying impedance and line widths, featuring a reflection section with a large change in impedance per unit length to minimize impedance mismatching, and an impedance conversion section with a gradual impedance transition to reduce reflections and insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a connector or via-hole conductor is used at the end portion of the signal line, then electrical connection is achieved, but impedance variation occurs causing impedance mismatching
Solution Approach 1:
The patent removes the connector or via-hole conductor from the signal line structure. Instead of using these separate components that cause impedance variation, the signal line is designed to extend directly to the end surface of the substrate, eliminating the source of impedance mismatching while maintaining electrical connection functionality.
Solution Approach 2:
Rather than adding impedance matching components (connectors, via-holes) to achieve proper impedance, the patent inverts the approach by designing the signal line itself to maintain consistent impedance throughout, including at the end portion. The solution flips the conventional wisdom of adding components to achieve impedance matching to instead using the signal line geometry alone.
2Reliability
If impedance matching components are added to correct impedance mismatching, then impedance matching improves, but device complexity increases
Solution Approach 1:
The signal line structure itself provides the impedance matching function without requiring separate matching components. By designing the signal line to extend to the end surface and control its dimensions, the structure achieves proper impedance matching intrinsically, making additional capacitors or matching networks unnecessary.
Solution Approach 2:
The signal line serves multiple functions simultaneously: it transmits the signal and also provides impedance matching. The same structural element (signal line) that carries the electrical signal is designed with specific dimensions and termination to also function as the impedance matching mechanism, eliminating the need for separate dedicated matching components.
Data Source
AI summary
A transmission line includes an element body and a signal conductor layer in the element body and having a linear shape. The transmission line includes a first, second, and third impedance sections, an impedance conversion section, and a reflection section. The second impedance section, the reflection section, the first impedance section, the impedance conversion section, and the third impedance section are positioned in this order along the signal conductor layer. Characteristic impedance of the first impedance section is lower than characteristic impedance in the second impedance section and characteristic impedance in the third impedance section. A change amount of characteristic impedance per unit length in the reflection section is larger than a change amount of characteristic impedance per unit length in the impedance conversion section.