Compact Marchand Balun Using Reduced Commensurate Frequency
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Solution Overview
Problem
Conventional Marchand baluns face challenges in achieving a compact size while maintaining performance, as high dielectric constants lead to manufacturing tolerances and increased insertion loss, and low dielectric constants result in larger conductor traces and higher DC resistance.
Innovation Solution
A compact Marchand balun design that operates at a reduced commensurate frequency, selected from a range between one-sixth and one-half of the normal frequency, using coupled transmission line structures and additional capacitors or open stubs to adjust the frequency without increasing the balun's size, allowing for arbitrary transformation ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If high dielectric constant materials are used to reduce balun size, then the operational frequency is reduced and size is minimized, but manufacturing tolerances become more pronounced and performance degrades
Solution Approach 1:
The patent changes the operating frequency parameter to be a fraction (one-sixth to one-half) of the normal Marchand balun frequency. This frequency reduction allows the use of lower dielectric constant materials while maintaining compact size, thereby avoiding the manufacturing tolerance issues associated with high dielectric constant materials.
2Volume of moving object
If high dielectric constant materials are used to reduce balun size, then the balun becomes more compact, but insertion loss increases
Solution Approach 1:
By operating at a reduced frequency (one-sixth to one-half of normal Marchand balun frequency), the patent enables the use of lower dielectric constant materials that exhibit lower loss tangents, thereby reducing insertion loss while maintaining compact balun dimensions.
3Manufacturing precision
If lower dielectric constant materials are used, then manufacturing tolerances are improved, but conductor trace widths must be smaller and lengths longer, increasing DC resistance
Solution Approach 1:
The reduced operating frequency allows the use of lower dielectric constant materials without requiring excessively narrow trace widths or excessive trace lengths. The frequency reduction compensates for the lower dielectric constant, enabling the use of wider, shorter traces that maintain low DC resistance.
4Area of stationary object
If the balun is made compact by stacking transmission line sections, then the X-Y plane size is reduced, but the profile height increases beyond acceptable limits
Solution Approach 1:
By operating at a reduced frequency, the patent achieves compact X-Y plane dimensions without requiring excessive stacking of transmission line sections. The lower operating frequency allows the quarter-wavelength transmission lines to be physically shorter, reducing the need for multi-layer stacking and thereby controlling the profile height within acceptable limits (0.4-0.6 mm for RF module integration).
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
The design achieves a significant reduction in operational frequency, reducing line length and maintaining compactness without high dielectric materials, while allowing for flexible transformation ratios and improved performance.
Implementation Method 1
A first set of coupled transmission line structures 22, 24, 26, 28 is coupled to an unbalanced port 1 and one port of a set of balanced differential ports 3, 4
Data Source
AI summary
The present invention is directed to a compact balun device that includes an unbalanced port and a set of balanced differential ports. A first set of coupled transmission line structures is coupled to the unbalanced port and one port of the set of balanced differential ports. The first set of coupled transmission line structures is characterized by at least one device parameter and a first length that is substantially equal to a quarter of a wavelength (λ). The wavelength (λ) corresponds to a first frequency. A second set of coupled transmission line structures is coupled to another port of the set of balanced differential ports. The second set of coupled transmission line structures is characterized by the at least one device parameter and a second length that is substantially equal to the quarter of a wavelength (λ). The wavelength (λ) corresponds to the first frequency. A plurality of interconnections couples the first set of coupled transmission line structures and the second set of coupled transmission line structures. The plurality of interconnections are configured such that the compact balun operates at a reduced operating frequency, the reduced operating frequency being selected from a range of frequencies by varying at least one device parameter. The range of frequencies is approximately between one-sixth of the first frequency and one-half the first frequency.