Multi-Winding Transformer with Variable Coupling for RF Power
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Solution Overview
Problem
Conventional on-chip transformers in RF transceiver design face challenges in achieving better coupling efficiency and minimizing coupling loss, particularly in varying output power conditions.
Innovation Solution
The transformer design incorporates multiple winding conductors with different transformation ratios and coupling factors, where a low coupling, high transformation ratio mode is used for low output power conditions and a high coupling, low transformation ratio mode is used for high output power conditions, achieved by varying the distance and inductance ratios between the conductors across different metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the distance between winding conductors is increased to achieve higher transformation ratio, then the coupling factor decreases causing coupling loss
Solution Approach 1:
The transformer is divided into multiple separate winding conductors (first, second, and third winding conductors) that can be independently configured. This segmentation allows different coupling factors between different conductor pairs, enabling the system to achieve both high transformation ratio (through first-second conductor pairing with larger distance) and good coupling efficiency (through second-third conductor pairing with smaller distance), thereby resolving the contradiction between transformation ratio and coupling loss.
2Loss of energy
If the coupling factor is increased to reduce coupling loss, then the transformation ratio decreases
Solution Approach 1:
Different local regions of the transformer structure are assigned different coupling characteristics. The first and second winding conductors are positioned with larger distance to achieve high transformation ratio, while the second and third winding conductors are positioned with smaller distance to achieve high coupling factor. This local differentiation of coupling quality allows the transformer to simultaneously optimize both transformation ratio and coupling efficiency in different parts of the structure.
3Adaptability or versatility
If multiple winding conductors with different transformation ratios are used to adapt to different output power conditions, then the device complexity increases
Solution Approach 1:
The transformer structure with multiple winding conductors is designed to serve multiple functions: it can operate in high transformation ratio mode (using first and second conductors) for low output power conditions, and in low transformation ratio mode (using second and third conductors) for high output power conditions. This multi-functionality allows a single transformer structure to adapt to different output power requirements without requiring separate transformers for each condition, thereby managing complexity while enhancing versatility.
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 enhances power efficiency by optimizing impedance transformation and reducing de-Q effects, while efficiently utilizing circuit area and adapting to different output power requirements.
Implementation Method 1
a second winding conductor, magnetically coupled to the first winding conductor
Data Source
AI summary
A transformer includes a first winding conductor and a second winding conductor, magnetically coupled to the first winding conductor. A first transformation ratio is achieved between the second winding conductor and the first winding conductor. A first distance between the first winding conductor and the second winding conductor is higher than a distance threshold, and accordingly, a first coupling factor between the first winding conductor and the second winding conductor is lower than a coupling factor threshold.