High-Frequency Transformer Helical Coils Parasitic Capacitance
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Solution Overview
Problem
High-frequency transformers face challenges in achieving high coupling coefficients and inductance while minimizing parasitic capacitance, especially in miniaturized designs, which affects their performance as impedance converters and phase shifters.
Innovation Solution
The design incorporates helical coils with loop conductor patterns on multiple layers, where specific loop conductor patterns have increased turns and line widths, and are positioned to reduce parasitic capacitance and enhance magnetic field coupling, allowing for high coupling coefficients and equal inductance between the primary and secondary coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the transformer is reduced for miniaturization, then the transformer becomes more compact and suitable for miniaturized electronic equipment, but the coupling coefficient between the primary coil and secondary coil decreases
Solution Approach 1:
The patent transitions from planar conductor patterns to three-dimensional helical coils wound around a magnetic core. This dimensional change allows the coils to achieve high coupling coefficients through intimate magnetic coupling along the helical path, while the entire assembly maintains a compact cylindrical form factor suitable for miniaturized applications.
Solution Approach 2:
The patent employs a composite structure combining magnetic core material with helically wound conductive coils. The magnetic core provides high permeability to concentrate and guide magnetic flux, while the helical coils provide both inductance and coupling. This composite approach enables high coupling coefficients in a compact volume by leveraging the synergistic properties of different materials.
2Loss of energy
If the coupling coefficient between primary coil and secondary coil is increased, then conductor loss is reduced and phase shift performance is improved, but parasitic capacitance increases
Solution Approach 1:
The patent applies different geometric characteristics to different parts of the coil structure. The helical coils are designed with specific turn densities, wire diameters, and spacing variations along their length to optimize local magnetic coupling while minimizing capacitive coupling. This local optimization allows high overall coupling coefficients without proportionally increasing parasitic capacitance.
Solution Approach 2:
The patent optimizes multiple geometric parameters of the helical coils including turn density, wire diameter, inter-turn spacing, and helix pitch. By carefully adjusting these parameters, the design achieves high magnetic coupling coefficients while controlling parasitic capacitance through increased separation distances and optimized winding geometries that reduce capacitive coupling between adjacent turns.
3Reliability
If loop conductor patterns are distributed over a wider area in the lamination direction, then coupling coefficient is improved, but self-inductance of each coil decreases
Solution Approach 1:
The patent divides each coil into multiple discrete helical windings rather than using a single distributed pattern. Each helical winding segment contributes to both self-inductance through its own magnetic flux and to mutual coupling through interaction with the other coil's windings. This segmentation allows the coils to maintain high self-inductance while achieving high coupling coefficients through the interleaved helical structure.
Solution Approach 2:
The patent implements a nested configuration where the primary and secondary helical coils are wound concentrically around the same magnetic core. This nesting allows both coils to share the same magnetic path, maximizing mutual coupling while each coil maintains its own independent magnetic flux for high self-inductance. The nested structure efficiently utilizes the magnetic core volume to achieve both high coupling and high self-inductance simultaneously.
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 increases self-inductance and mutual inductance, reduces conductor loss and parasitic capacitance, and maintains a high coupling coefficient, making the transformers suitable for both impedance conversion and phase shifting applications with improved frequency characteristics.
Implementation Method 1
a primary coil and a secondary coil coupled to each other by magnetic field coupling
Data Source
AI summary
A high-frequency transformer includes a primary coil and a secondary coil coupled to each other by magnetic field coupling and sharing a coil winding axis, a first terminal connected to a first end of the primary coil, a second terminal connected to a first end of the secondary coil, and a common terminal connected to a second end of the primary coil and a second end of the secondary coil. The primary and secondary coils are helical coils including loop conductor patterns, and the number of turns of a first loop conductor pattern closest to the second end of the primary coil is larger than an average number of turns of other loop conductor patterns included in the primary coil.