Transmission Line Coupling for Low Reflection Coefficients
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Solution Overview
Problem
Existing circuit designs with transmission lines of different widths face significant reflection coefficients when the distance between them is shorter than the wavelength of the frequency signals, leading to inefficient signal transmission and potential for larger reflection coefficients.
Innovation Solution
A coupling mechanism with specific width transitions at each end, where the first coupling width is larger than the narrower transmission line width and the second coupling width is smaller than the wider transmission line width, is used to minimize reflection coefficients, allowing for efficient signal transfer even at distances shorter than the wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a taper is used to interconnect transmission lines with different line widths, then signal transmission is improved, but the reflection coefficient becomes relatively large when the distance between transmission lines is smaller than 20% of the wavelength
Solution Approach 1:
The patent changes the geometric parameters of the coupling structure by introducing a first coupling width larger than the first line width and a second coupling width smaller than the second line width. This parameter optimization resolves the contradiction by achieving low reflection coefficients even at distances smaller than 20% of the wavelength, whereas conventional tapers fail in this regime.
2Volume of moving object
If the distance between ends of transmission lines is reduced to achieve compact design, then device size is reduced, but the reflection coefficient becomes relatively large
Solution Approach 1:
The patent optimizes the coupling structure parameters (first coupling width and second coupling width) to maintain low reflection coefficients even when the distance between transmission lines is reduced to 10%, 5%, or 1% of the wavelength, enabling compact device design without suffering from high reflection coefficients.
3Ease of manufacture
If transmission lines with different line widths are coupled using conventional methods, then interconnection is achieved, but impedance matching deteriorates leading to high reflection coefficients
Solution Approach 1:
The patent introduces optimized coupling parameters where the first coupling width is larger than the first line width and the second coupling width is smaller than the second line width. This parameter optimization achieves excellent impedance matching between transmission lines of different widths, reducing reflection coefficients while maintaining ease of interconnection.
Data Source
AI summary
In a circuit (1) comprising first and second transmission lines (11,12) with first and second line widths, the transmission lines (11,12) are coupled to each other via a coupling (13,14) with first and second coupling widths at its ends, such that a smaller one of the line widths and a larger one of the coupling widths are combined, and such that a larger one of the line widths and a smaller one of the coupling widths are combined. Such a coupling (13,14) introduces relatively small reflection coefficients, for example for distances between ends of the transmission lines (11,12) smaller than a wavelength of frequency signals to be exchanged via the transmission lines (11,12) and the coupling (13,14). The circuit (1) can then become more compact. The coupling (13,14) may comprise one single taper or may comprise a first taper (13) with a first, larger coupling width and a second taper (14) with a second, smaller coupling width.