Transmission Line Transformer with AC-Grounded Coupling

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Solution Overview

Problem

Existing transmission line transformers have difficulty achieving large impedance transformation ratios, leading to challenges in reducing the size of impedance matching circuits.

Innovation Solution

A transmission line transformer configuration with a first and second transmission line disposed at different positions in the thickness direction of a substrate, connected in series, and a third transmission line electromagnetically coupled between them, where one end of the third transmission line is AC-grounded, allowing for increased impedance transformation ratios without increasing circuit size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a plurality of transmission line transformers are cascade-connected to achieve a desired impedance transformation ratio, then the impedance transformation ratio is improved, but the device complexity and size increase

Engineering Contradiction:

Improveimpedance transformation ratioVSAvoidcircuit size

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces a third transmission line extending in the thickness direction of the substrate, perpendicular to the plane of the first and second transmission lines. This three-dimensional arrangement enables a single transformer to achieve a large impedance transformation ratio (e.g., 9:1 or 25:1) without requiring multiple cascade-connected transformers, thereby reducing circuit size and complexity while maintaining the desired impedance transformation capability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The third transmission line is positioned between the first and second transmission lines in the thickness direction, creating a nested three-layer structure. This compact nested arrangement allows all three transmission lines to occupy a small volume, achieving large impedance transformation ratios within a confined space without requiring multiple separate transformer units

Inventive Principle:

Principle #7Nested doll (Nesting)

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 larger impedance transformation ratio than traditional methods, enabling a reduction in the size of impedance matching circuits while maintaining low insertion loss.

Implementation Method 1

The first transmission line and the second transmission line are electromagnetically coupled to the third transmission line

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Data Source

PatentUS11522503B2Transmission line transformer and amplifying circuit

Publication Date: 2022.12.06 MURATA MFG CO LTD

AI summary

A first transmission line and a second transmission line that are connected in series to each other are disposed at different positions in a thickness direction of a substrate. A third transmission line is disposed between the first transmission line and the second transmission line in the thickness direction of the substrate. The third transmission line includes a first end portion connected to one end portion of the first transmission line, and a second end portion that is AC-grounded. The first transmission line and the second transmission line are electromagnetically coupled to the third transmission line.