Stacked RF Transformer With Fractional Windings to Reduce Reflections
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Solution Overview
Problem
RF transformers face challenges in miniaturization and performance optimization, particularly at high frequencies, due to large physical sizes, high capacitance, and limited coupling coefficients, which hinder integration and increase costs and signal reflections.
Innovation Solution
The design incorporates a primary winding and a secondary winding with fractional sections connected in parallel, optimizing coupling coefficients and reducing impedance, while maintaining a high Q factor and resonance frequency, using a substrate and insulating materials to minimize capacitance and reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional integrated circuit designs are used for RF transformers, then integration is achieved, but high capacitance and poor Q factors result at high frequencies
Solution Approach 1:
The secondary winding is divided into multiple fractional sections that are connected in parallel. This segmentation reduces the capacitance between winding turns while maintaining the required transformation ratio, thereby improving the Q factor and performance at high frequencies while keeping the transformer integrated
Solution Approach 2:
The patent transitions from planar windings to three-dimensional stacked windings with vertical separation. This dimensional change reduces parasitic capacitance between primary and secondary windings while maintaining magnetic coupling, enabling better high-frequency performance in an integrated structure
2Reliability
If surface mount transformers are used, then high frequency operation is achieved, but large physical size consumes valuable circuit board space
Solution Approach 1:
The transformer windings are stacked vertically one above the other in a nested configuration. This three-dimensional arrangement achieves the required magnetic coupling and high-frequency performance while minimizing the horizontal footprint on the circuit board, effectively nesting the magnetic paths in the vertical dimension
3Adaptability or versatility
If integrated transformers with multiple turns are used, then impedance transformation is achieved, but unwanted reflections from secondary to primary winding occur
Solution Approach 1:
The secondary winding is segmented into multiple fractional sections connected in parallel. This segmentation reduces the voltage swing across each individual section, thereby reducing the magnitude of reflections from the secondary to primary winding while maintaining the overall impedance transformation ratio
Solution Approach 2:
The fractional sections act as intermediaries between the primary winding and the full secondary output. By distributing the magnetic coupling through multiple intermediate sections, the patent reduces direct high-voltage reflections while achieving the required transformation ratio
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 compact, high-performance RF transformers with improved coupling coefficients, reduced impedance, and minimized signal reflections, facilitating integration and cost-effective production.
Implementation Method 1
a primary winding and a secondary winding with fractional sections connected in parallel, optimizing coupling coefficients
Implementation Method 2
using a substrate and insulating materials to minimize capacitance and reflections
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.