Multi-branch Transmission Line for Compact Impedance Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-output integrated circuit devices face challenges in reducing the size of impedance matching circuits due to the length of ¼ wavelength lines, which are necessary for wideband characteristics, leading to packaging issues despite the use of bent line patterns.
Innovation Solution
The implementation of a transmission line with multiple branch lines of equal length, including bent shapes, where the first ends are connected to a common terminal and the second ends are connected to another common terminal, allowing for reduced line widths and lengths, thereby minimizing the overall circuit size while maintaining impedance matching and low transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ¼ wavelength lines are used for impedance matching to achieve wideband characteristics, then the matching performance is improved, but the circuit size is increased due to the long line length
Solution Approach 1:
The transmission line is divided into multiple branch lines (first branch line, second branch line, etc.) that are connected in parallel between input and output terminals. Each branch line has a specific length and characteristic impedance, and by combining multiple segmented lines, the patent achieves wideband impedance matching while reducing the overall circuit footprint compared to a single long ¼ wavelength line.
Solution Approach 2:
The patent transitions from a single-dimensional long transmission line to a multi-branch parallel structure that utilizes spatial arrangement in multiple dimensions. The branch lines are arranged in parallel and can be configured with different lengths and impedances, effectively using dimensional space to achieve the matching function with reduced overall length.
2Power
If the gate width of transistor is increased to increase the output, then the output power is improved, but the output impedance is reduced to 1Ω or less requiring more complex impedance transformation
Solution Approach 1:
The impedance transformation is achieved by segmenting the matching circuit into multiple parallel branch lines, each with specific characteristic impedances (e.g., 70Ω, 35Ω, 18Ω). This segmented approach provides stepped impedance transformation from the low output impedance (1Ω or less) to the standard 50Ω, making the transformation process manageable and systematic rather than requiring a single complex transformer.
Solution Approach 2:
The patent utilizes parameter changes in the branch lines, specifically varying the characteristic impedances and lengths of each branch line, to achieve the required impedance transformation. By adjusting these parameters, the circuit transforms the low output impedance of the wide-gate transistor to the standard 50Ω while maintaining wideband characteristics.
3Reliability
If a plurality of impedance transformers are connected in series to convert low output impedance to 50Ω, then the impedance matching is improved, but the circuit size is increased
Solution Approach 1:
The patent merges multiple impedance transformation functions into a single parallel branch structure rather than connecting multiple transformers in series. The multiple branch lines work simultaneously to provide the impedance transformation from low impedance to 50Ω, combining several functions into one integrated circuit that achieves the same result with reduced size.
Solution Approach 2:
Instead of extending the circuit in one dimension by connecting transformers in series, the patent uses a parallel branch configuration that utilizes spatial arrangement in another dimension. This allows the impedance transformation to occur across multiple parallel paths simultaneously, reducing the overall circuit length while maintaining the transformation function.
Data Source
AI summary
A transmission line having a plurality of branch lines that respectively include a first end part and a second end part and have a same line length, in which at least part of the plurality of branch lines includes bent shapes, the first end parts of the plurality of branch lines are connected to a common terminal, and the second end parts of the plurality of branch lines are connected to a common terminal. The plurality of branch lines may include two micro strip lines that are formed on substrates having the same dielectric constant and have bent shapes in symmetry with each other with respect to a straight line.