Stacked On-Chip Transformer Windings for High Coupling and Low Loss
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Solution Overview
Problem
Current transformer manufacturing techniques face challenges in miniaturization, leading to increased resistance and reduced quality factor (Q) due to spatial constraints, with vertical winding transformers experiencing self-resonance issues and horizontal transformers having inefficiencies from reduced coupling factors.
Innovation Solution
The design of stacked-layer transformers with shared wire elements and strategically positioned windings allows for both primary and secondary windings to be formed from low-resistant metal in a single manufacturing step, maximizing mutual coupling and minimizing resistance and insertion losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If transformers are miniaturized to fit spatial constraints, then device size is reduced, but resistance increases and quality factor decreases
Solution Approach 1:
The patent transitions from planar (2D) winding configurations to a three-dimensional stacked-layer architecture. Multiple winding layers are stacked vertically with interconnection elements connecting corresponding nodes between layers, effectively utilizing the vertical dimension to increase coupling area and reduce resistance without increasing the device footprint, thereby maintaining high quality factor in miniaturized transformers.
Solution Approach 2:
The patent implements nested winding structures where secondary windings are positioned within the spatial envelope of primary windings, and multiple winding layers are stacked concentrically. This nesting approach maximizes the use of available space, increases mutual coupling between windings, and reduces resistance by providing multiple parallel conduction paths, thus improving quality factor in compact designs.
2Area of stationary object
If vertical winding configuration is used, then spatial efficiency is improved, but self-resonance issues increase
Solution Approach 1:
The patent distributes windings across multiple vertical layers separated by insulating substrates, transforming the single-plane vertical winding into a multi-layer structure. This dimensional distribution increases the effective distance between primary and secondary windings, reducing parasitic capacitance and self-resonance effects while maintaining compact footprint through vertical stacking.
3Reliability
If horizontal winding configuration is used, then coupling factor is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the transformer structure into discrete stacked layers, each containing a portion of the windings. Corresponding nodes between layers are connected through vertical interconnection elements. This segmentation allows each layer to be manufactured and positioned independently, simplifying the overall manufacturing process while achieving high mutual coupling through the stacked architecture.
Solution Approach 2:
The patent employs universal manufacturing techniques including standard photolithography patterning for winding traces, conventional thin-film deposition for metal layers, and standard etching processes for interconnection elements. These multi-functional processes can create all transformer components (windings, interconnections, insulation) in a unified manufacturing flow, reducing complexity despite the three-dimensional structure.
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 enhances the quality factor (Q) and reduces insertion losses while maintaining high mutual coupling, improving transformer performance and efficiency compared to traditional vertical and horizontal winding configurations.
Implementation Method 1
When current flows through a primary winding, an electromagnetic field is created such that electrical energy is induced from the primary winding to a secondary winding
Data Source
Figure 1
Figure 1A
Figure 2A
AI summary
A stacked transformer or inductor apparatus including a first layer with a first layer wire element extending around a center axis and a second layer with a second layer wire element. The second layer element includes side by side first and second wire components in parallel spaced relation extending around the center axis and the first wire component is connected to the first layer wire element to form a primary turn winding. A third layer includes a third layer wire element extending around the center axis and connected to the second wire component of the second layer wire element to form a secondary turn winding partially overlapping with the primary turn winding.