Stacked Integrated Transformer With Fractional Windings for RF Reflections
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Solution Overview
Problem
Transformers in RF circuits face challenges with non-scalable physical sizes, high capacitance, and performance degradation at high frequencies, leading to space consumption and increased costs, with issues such as unwanted reflections, poor Q factors, and unbalanced coupling coefficients.
Innovation Solution
The design incorporates a primary winding and a secondary winding with fractional sections connected in parallel, optimized for high coupling coefficients and reduced capacitance, using a substrate with shield sections and waterfall transitions to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional integrated transformers are used at high frequencies, then impedance transformation and isolation functions are achieved, but unwanted reflections occur from secondary winding to primary winding and Q factors deteriorate
Solution Approach 1:
The secondary winding is divided into multiple fractional sections that are connected in parallel. This segmentation reduces the capacitance between winding sections and minimizes unwanted reflections from the secondary winding to the primary winding, thereby improving transformer performance stability at high frequencies
Solution Approach 2:
The patent applies different connection configurations to different sections of the secondary winding. By optimizing the local arrangement and connection of each fractional section, the transformer achieves improved Q factors and reduced reflections while maintaining the overall transformation ratio
2Speed
If surface mount transformers are used, then high frequency operation is achieved, but device size increases and circuit board space is consumed
Solution Approach 1:
The transformer design transitions from a planar surface mount configuration to a three-dimensional stacked architecture. Multiple windings are arranged in different layers and connected through vertical interconnects, enabling high-frequency operation while significantly reducing the footprint area on the circuit board
3Speed
If integrated transformers with multiple turns are used for high inductance, then lower frequency performance is improved, but device size increases and manufacturing cost increases
Solution Approach 1:
The patent employs composite winding structures combining multiple conductive materials and configurations. By using fractional sections with parallel connections and optimized material selection, the transformer achieves high inductance values without proportionally increasing the device volume, making it suitable for both low and high frequency applications
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 compact form factor with improved Q factors, reduced series resistance, and minimized reflections, maintaining performance at high frequencies while optimizing space and cost.
Implementation Method 1
The secondary winding, on the substrate, comprises two or more fractional sections, connected in parallel, which together form a complete turn such that each of the two or more fractional sections are adjacent the primary winding to maximize coupling
Implementation Method 2
using a substrate with shield sections and waterfall transitions to minimize interference
Data Source
AI summary
A transformer comprising a primary winding and a secondary winding. The primary winding has N2 number turns and having a first terminal and a second terminal. The secondary winding has having N1 fractional portions, which together form a full turn, are in close proximity to the primary winding to establish coupling between the primary winding and the N1 fractional coil portions, the transformer turn ratio from the primary winding to the secondary winding is N2:(N3/N1) where N2 is an integer equal to or greater than 1, N1 is an integer greater than or equal to 2, and N3 is an integer greater than or equal to 1. Also disclosed is a stacked integrated transformer having a primary winding and secondary winding of which one or both have a waterfall structure and a portion of which functions as a ground connected shield between the secondary winding and the primary winding.