Compact Marchand Balun Using Segmented Coupling Units
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Solution Overview
Problem
Marchand baluns typically have an enlarged size due to their implementation of four quarter-wavelength transmission lines, which makes them unsuitable for compact designs, especially when used at lower frequencies, as they degrade reflection characteristics.
Innovation Solution
The design incorporates first and second coupling units with transmission lines of lengths between λ/16 and 3λ/16, and an additional unit such as a transmission line or capacitor, to reduce the overall size while maintaining effective signal conversion and reflection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four quarter-wavelength transmission lines are used in a marchand balun, then the signal conversion function is achieved, but the device size is enlarged
Solution Approach 1:
The patent changes the length parameter of transmission lines from the conventional λ/4 to a range of λ/16 to 3λ/16. This parameter modification allows the balun to maintain its signal conversion function while reducing the overall device size, as shorter transmission lines occupy less space on the substrate.
Solution Approach 2:
The patent divides the traditional four-transmission-line structure into two coupling units, each containing two transmission lines. This segmentation allows for more flexible layout and optimization of the transmission line lengths, enabling size reduction while preserving the required signal conversion functionality between balanced and unbalanced modes.
2Area of stationary object
If transmission line length is reduced to decrease device size, then plane size is reduced, but reflection characteristics deteriorate at lower frequencies
Solution Approach 1:
The patent specifies a particular length range (λ/16 to 3λ/16) for the transmission lines that optimizes the balance between size reduction and maintaining reflection characteristics. This parameter optimization ensures that even with shorter lines, the balun maintains acceptable performance at lower frequencies by preventing excessive signal reflection.
Solution Approach 2:
The patent introduces an additional transmission line or capacitor as an intermediary element to compensate for the potential degradation in reflection characteristics caused by using shorter transmission lines. This additional component helps maintain proper impedance matching and signal integrity, ensuring reliable reflection characteristics are preserved despite the reduced line lengths.
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 allows for a compact marchand balun with improved reflection characteristics at lower frequencies, reducing the device's plane size without degrading transmission performance, making it suitable for higher frequency applications when used at lower frequencies.
Implementation Method 1
A marchand balun comprises a first coupling unit, a second coupling unit, and an additional unit. The first coupling unit includes a first transmission line and a second transmission line coupled with the first transmission line.
Data Source
AI summary
A marchand balun with a reduced plane size is disclosed. The marchand balun provides two coupling units each having two transmission lines coupled to each other and having a length of λ/8, where λ is a characteristic wavelength of a signal subject to the marchand balun. The marchand balun further provides an additional unit, where two coupling unit and the additional unit are connected in series to each other. The additional unit is one of a transmission line with a length of λ/16 with one open end and a capacitor with one grounded end.