Balun Transformer With Interwoven Windings For Bandwidth
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Solution Overview
Problem
Existing balun transformers face challenges with substantial inter-winding capacitance limiting operating bandwidth and asymmetric geometries due to undesirable center tap locations, leading to increased manufacturing complexity, size, and DC voltage loss.
Innovation Solution
A balun transformer design utilizing a substantially symmetrical configuration with only two metal layers, where the primary and secondary windings form interwoven paths with a center tap accessible on the same side, reducing the need for additional metal layers and improving isolation and frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flux-coupled balun transformer is created by winding two separate wires around a magnetic core with grounding one side of the primary winding, then impedance matching between unbalanced line and balanced load is achieved, but the geometry becomes asymmetric and requires additional metal layers increasing manufacturing complexity
Solution Approach 1:
The patent applies asymmetry principle by intentionally creating an asymmetric winding structure where the primary winding has a center tap accessible on the same side as the secondary winding, while the overall geometry maintains functional symmetry for balanced-to-unbalanced transformation. This asymmetric design allows the center tap to be accessible without requiring additional metal layers, thus reducing manufacturing complexity while maintaining the required geometric properties for proper balun operation
2Loss of energy
If the center tap is disposed at an undesirable location to achieve asymmetric geometry, then impedance transformation is achieved, but DC voltage loss increases due to higher resistance
Solution Approach 1:
The patent applies local quality principle by optimizing the local position of the center tap on the primary winding to be accessible on the same side as the secondary winding. This local optimization reduces the resistance path for DC current while maintaining the overall asymmetric geometry needed for impedance transformation, thereby reducing DC voltage loss without compromising the center tap functionality
3Adaptability or versatility
If certain geometries are used to achieve impedance transformation, then balun functionality is achieved, but inter-winding capacitance increases limiting operating bandwidth
Solution Approach 1:
The patent applies the dimensionality change principle by transitioning from a planar two-dimensional winding layout to a three-dimensional interwoven structure where the primary and secondary windings are intertwined in multiple dimensions. This spatial reconfiguration reduces the inter-winding capacitance by increasing the effective distance between opposing conductors while maintaining compact footprint, thereby extending operating bandwidth without significantly increasing device complexity
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 design enhances manufacturability, reduces size and cost, maintains improved broadband frequency response, and provides better isolation and common mode rejection ratio, addressing the limitations of existing balun transformers.
Implementation Method 1
The transfer of energy may be accomplished through electromagnetic mutual induction, i.e., where time-varying current through a primary conductor produces a time-varying magnetic flux through a secondary conductor. As a result of Faraday's law of induction, the changing flux induces an electromotive force in the secondary conductor that gives rise to a current.
Implementation Method 2
As a result of Faraday's law of induction, the changing flux induces an electromotive force in the secondary conductor that gives rise to a current. The voltage in the secondary conductor is typically provided by the ratio of the number of windings of the secondary conductor relative to the number of windings in the primary conductor multiplied by the voltage of the primary conductor
Data Source
AI summary
A balanced-to-unbalanced (balun) transformer may include two metal layers on a substrate, a first winding following a first winding path, and a second winding following a second winding path, where each winding is formed in one or more of the two metal layers. The winding paths may include winding segments each disposed around a central axis of the balun transformer, where connectors join adjacent winding segments such that the winding paths are continuous between ends of the windings. The second winding path may be interwoven with, but independent from, the first winding path to form a resultant pattern that is substantially symmetrical. The second winding may include a number, n, of sub-windings, where n>1 such that a resultant number of winding segments of the second winding is greater than a resultant number of winding segments of the first winding by a factor of n.