Directional Coupler Layout for Stronger Coupling in Less Space
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing directional couplers face challenges in increasing the degree of coupling between main and sub-lines without enlarging the overall size, as lengthening the coupling portion to achieve desired coupling strengths results in increased substrate size.
Innovation Solution
The directional coupler configuration includes a substrate with a first and second main line and a first sub-line, where the sub-line is partially overlapping with the main line, and the conductor patterns are disposed such that their principal surfaces face each other, enhancing electric field coupling and allowing for larger coupling without increasing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling portion length is increased to obtain desired coupling strength, then the degree of coupling is improved, but the substrate size increases
Solution Approach 1:
The invention transitions from planar coupling (lines in the same layer) to three-dimensional coupling by positioning the sub-line in a different layer that overlaps with the main line. This vertical arrangement increases the effective coupling area without extending the horizontal length, thereby achieving desired coupling strength while suppressing substrate size increase.
Solution Approach 2:
The sub-line is positioned within the projection area of the main line by utilizing the vertical space in different layers. This nesting arrangement allows the coupling portion to be compact while maintaining a large effective coupling area, resolving the contradiction between coupling strength and substrate size.
2Reliability
If the coupling portion length is increased to obtain desired coupling strength, then the degree of coupling is improved, but the equivalent series resistance increases
Solution Approach 1:
By moving the sub-line to a different layer that overlaps with the main line, the invention achieves large coupling area in three dimensions without increasing the horizontal length of the coupling portion. This reduces the path length for signal transmission and minimizes equivalent series resistance while maintaining coupling strength.
3Reliability
If the coupling portion length is increased to obtain desired coupling strength, then the degree of coupling is improved, but the insertion loss increases
Solution Approach 1:
The invention achieves large coupling area by utilizing vertical stacking in different layers rather than horizontal extension. This reduces the overall path length for signal transmission through the coupling portion, thereby decreasing insertion loss while maintaining the desired degree of coupling.
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 configuration achieves a higher degree of electromagnetic field coupling, reducing the size of the directional coupler while maintaining or exceeding the coupling strength of existing designs, and decreases equivalent series resistance and insertion loss.
Implementation Method 1
the first main line and the first sub-line are disposed in such a manner that principal surfaces of the conductor patterns face each other. An area of the principal surface of the conductor pattern is typically larger than an area of a side surface thereof. Because of this, electric field coupling between the first main line and the first sub-line is increased in strength
Data Source
AI summary
A directional coupler includes a substrate, a main line 121, a main line 122, and a sub-line. The main line 121 and the main line 122 each include a conductor pattern formed in the substrate, and are connected in parallel to each other. The sub-line includes a conductor pattern formed in the substrate. The sub-line is disposed at a position at least partially overlapping with the main line 121 in a plan view of the substrate.