Integrated Transformer Stacked Coils RF Pulling
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Solution Overview
Problem
Integrated transformers in high-frequency applications face challenges such as limited tuning range, VCO pulling, and tight phase noise performance and efficiency requirements, particularly in RF circuits like local oscillators and filters.
Innovation Solution
The design of an integrated transformer with stacked primary and secondary coils arranged face to face, where each coil extends over two planes with connector fingers that traverse planes to connect subsections, providing efficient interconnection and improved symmetry, immunity to adjacent block pulling, and suitable for high-performance RF applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If integrated transformer is designed for high-frequency applications, then performance in RF circuits is improved, but device footprint and integration density are constrained
Solution Approach 1:
The patent transitions from planar coil arrangements to a three-dimensional stacked configuration where primary and secondary coils are positioned on different substrate layers. This vertical stacking enables electromagnetic coupling in the Z-direction while reducing the lateral footprint on the substrate, effectively resolving the contradiction between high-frequency performance and compact device area.
Solution Approach 2:
The design embeds multiple functional elements within a compact vertical structure: connector fingers are nested between coil windings, via holes traverse through substrate layers to connect different planes, and the entire transformer assembly is integrated into the RF circuit substrate. This nesting approach maximizes component density while maintaining electrical performance.
2Area of stationary object
If connector fingers are made narrower to reduce footprint, then device area is reduced, but connection reliability between subsections deteriorates
Solution Approach 1:
The connector fingers utilize the vertical dimension by extending through via holes that traverse multiple substrate layers. This allows the connectors to maintain adequate width for reliable electrical connection while the overall device footprint in the XY-plane remains compact. The connection path moves from a purely lateral arrangement to a three-dimensional configuration.
Solution Approach 2:
The connector structure employs composite construction combining conductive finger materials with substrate materials and dielectric layers. This composite approach allows optimization of each material's properties: the conductive fingers provide low-resistance electrical connection, the substrate provides mechanical support, and the dielectric layers provide electrical isolation, achieving both compact size and connection reliability.
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 achieves a high level of integration, symmetrical response, good quality-factor, and reduced device footprint with improved immunity to pulling effects, making it suitable for high-performance RF and millimeter-wave applications.
Implementation Method 1
The primary coil comprises a first subsection and a second subsection. The first subsection extends in a first plane and the second subsection extends in a second plane
Data Source
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AI summary
An integrated transformer comprising a primary coil and a secondary coil, the primary coil comprising a first subsection and a second subsection, the first subsection extending in a different plane to a plane in which the second subsection extends, the planes spaced from one another, the secondary coil comprising a first subsection and a second subsection, the first subsection extending in a different plane to a plane in which the second subsection extends, the planes spaced from one another, wherein the first subsection of the primary coil is stacked with the second subsection of the secondary coil and the second subsection of the primary coil is stacked with the first subsection of the secondary coil.