Directional Coupler-Integrated Board Miniaturization
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Solution Overview
Problem
Existing directional couplers face challenges in miniaturization while maintaining high directivity and coupling characteristics, as the element values of capacitors and inductors need to be within specific limits to be integrated with a board, and adjusting these values to improve characteristics can exceed integration limits or result in insufficient performance.
Innovation Solution
A directional coupler-integrated board configuration that includes a main line and a secondary line electromagnetically coupled, with a first capacitor in parallel with the secondary line, a second capacitor connecting the secondary line to ground, an impedance element with lower impedance than the normalized impedance, and a matching circuit to match impedance at the coupling port, all integrated with a multilayer circuit board, allowing for improved directivity and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the element value of the capacitor is increased to improve directivity, then the directivity is improved, but the capacitor cannot be integrated with the board due to exceeding the upper limit
Solution Approach 1:
The invention divides the single capacitor function into two separate capacitors: a first capacitor connected in parallel with the secondary line to improve directivity, and a second capacitor connecting the other end of the secondary line to ground to enable integration. This segmentation allows each capacitor to have smaller element values that can be integrated with the board while collectively achieving the desired directivity improvement.
Solution Approach 2:
The invention introduces an impedance element as an intermediary component between the secondary line and ground. This impedance element, having an impedance lower than the normalized impedance, works together with the two capacitors to achieve both directivity improvement and integration feasibility by mediating the impedance transformation and enabling compact element values.
2Volume of moving object
If the directional coupler is miniaturized by integrating with the board, then the size is reduced, but the characteristics improvement becomes insufficient due to element value limitations
Solution Approach 1:
The invention segments the coupling function into two capacitors with different connections: the first capacitor in parallel with the secondary line provides directivity enhancement, while the second capacitor to ground enables impedance control for integration. This segmentation allows the directional coupler to be miniaturized through board integration while maintaining sufficient characteristic improvement.
Solution Approach 2:
The invention changes the circuit configuration parameters by introducing two capacitors with specific connections and an impedance element. This parameter change enables the element values to be reduced to levels suitable for board integration while still achieving the necessary directivity and coupling characteristics through the transformed circuit topology.
3Ease of manufacture
If the element values are limited for integration, then the miniaturization is achieved, but the characteristics improvement becomes insufficient
Solution Approach 1:
The invention segments the single capacitor into two capacitors with different configurations, allowing each to have smaller element values suitable for integration. The first capacitor in parallel with the secondary line and the second capacitor to ground work together to achieve both integration feasibility and sufficient characteristic improvement.
Solution Approach 2:
The impedance element serves as an intermediary that enables the two capacitors with limited element values to collectively achieve the desired characteristics. By mediating the impedance transformation, it allows the system to overcome the limitations of individual small-capacitor values and achieve sufficient directivity improvement while maintaining integrability.
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 both improved radio-frequency characteristics and miniaturization by limiting element values to enable integration with a multilayer circuit board, reducing the size of the directional coupler while maintaining high reliability and flexibility in layout.
Implementation Method 1
The secondary line is electromagnetically coupled to the main line
Data Source
AI summary
A coupler-integrated board includes a coupler, a first capacitor, a second capacitor, a resistance element, a matching circuit, and a multilayer circuit board. The coupler includes a main line and a secondary line. The first capacitor is connected in parallel with the secondary line. The second capacitor connects another end of the secondary line to a ground. The resistance element connects the other end of the secondary line to the ground. The resistance element has an impedance lower than a normalized impedance at a predetermined frequency. The matching circuit is connected between one end of the secondary line and a coupling port. The matching circuit matches an impedance at the coupling port to the normalized impedance at the predetermined frequency. The multilayer circuit board includes laminated base material layers. The coupler is integrated with the multiplayer circuit board.