Multilayer Impedance Conversion Circuit with Overlapping Coils
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Solution Overview
Problem
Miniaturized antennas in wireless communication devices face challenges in impedance matching across different frequency bands due to varying impedance of radiation elements, leading to a narrow available band and difficulties in achieving a predetermined impedance conversion ratio with small transformer coils.
Innovation Solution
The method involves a multilayer impedance conversion circuit with overlapping coil elements in a lamination direction, connecting primary and secondary coils in parallel, and defining the impedance conversion ratio based on the lamination order of coil elements within the multilayer body, maintaining a high coupling coefficient and allowing for a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary coil and secondary coil are made to have the same shape and disposed to overlap with each other to obtain a high coupling coefficient, then the coupling coefficient is improved, but the degree of freedom to define each inductance is reduced and it becomes extremely difficult to obtain a predetermined impedance ratio
Solution Approach 1:
The patent divides the transformer into two separate transformers (first transformer and second transformer), each with its own primary and secondary coils. This segmentation allows independent control of inductance values while maintaining overlapping coil structures for high coupling coefficients in both transformers simultaneously.
Solution Approach 2:
The patent combines two transformers in parallel configuration where the primary coils are connected in parallel and the secondary coils are connected in parallel. This merging approach allows the system to achieve both high coupling coefficients (through overlapping coils in each transformer) and flexible impedance ratio control (through the parallel combination of transformers with different inductance ratios).
2Volume of moving object
If the impedance conversion circuit is miniaturized to meet compact antenna requirements, then the size is reduced, but the inductance of the coils becomes extremely small (several nH) causing magnetic flux to be insufficient and coupling coefficient to decrease
Solution Approach 1:
The patent employs a nested structure where the primary coil and secondary coil are positioned to overlap with each other in the vertical direction. This nesting approach maximizes the magnetic coupling between coils within a minimal footprint, enabling high coupling coefficients even when the overall transformer size is reduced to several millimeters.
Solution Approach 2:
The patent utilizes the vertical dimension (lamination direction) to achieve coil overlap and magnetic coupling. By arranging coils in different layers that overlap when viewed from above, the system achieves strong coupling without increasing the horizontal footprint, thus maintaining compact size while ensuring sufficient magnetic flux linkage.
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 enables the definition of a predetermined impedance conversion ratio while maintaining a high coupling coefficient, even in a compact size, effectively addressing the impedance matching challenges across different frequency bands.
Implementation Method 1
a first transformer including a primary side coil element and a secondary side coil element being coupled to each other through an electromagnetic field
Data Source
AI summary
Coil openings of a primary side coil element of a first transformer, a secondary side coil element of the first transformer, a primary side coil element of a second transformer, and a secondary side coil element of the second transformer overlap with one another when viewed from above in a lamination direction. The primary side coil element of the first transformer and the primary side coil element of the second transformer are connected in parallel, and the secondary side coil element of the first transformer and the secondary side coil element of the second transformer are connected in parallel. An impedance conversion ratio is defined in accordance with a lamination order of the primary side coil element and the secondary side coil element of the first transformer with respect to a lamination order of the primary side coil element and the secondary side coil element of the second transformer within a multilayer body.