Semiconductor Switch Branch Line Impedance Matching
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Solution Overview
Problem
Conventional semiconductor switches operating in millimeter wave bands face challenges in reducing transmission loss and size, as they require transmission lines of specific lengths to maintain impedance matching, leading to increased dimensions and limitations in miniaturizing transceivers, transmitters, and receivers.
Innovation Solution
A semiconductor switch design with branch lines of reduced length, where switching devices are shunt-connected between branch lines and ground, allowing for impedance matching between the main line and branch lines, enabling efficient RF signal switching with reduced size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If transmission lines are designed with specific lengths (one-quarter wavelength) to maintain impedance matching, then transmission loss is reduced, but the device size increases
Solution Approach 1:
The patent changes the electrical parameters of the transmission lines by introducing discontinuities (changes in width, position, or configuration) along the lines. These discontinuities modify the characteristic impedance and electrical length of the transmission lines, allowing them to achieve the required impedance matching function with physically shorter lengths. This directly addresses the contradiction by changing the electrical properties rather than relying solely on physical length.
Solution Approach 2:
The patent introduces additional design dimensions beyond simple line length by incorporating width variations, positional offsets, and multi-segment configurations of the transmission lines. These dimensional changes allow the transmission lines to achieve complex impedance transformation functions that would otherwise require much longer uniform lines, thereby reducing the overall device footprint while maintaining low transmission loss.
2Length of stationary object
If transmission lines are shortened to reduce device size, then device dimensions are reduced, but impedance matching becomes difficult
Solution Approach 1:
The patent employs multiple adjustable parameters including transmission line width, position, segmentation, and discontinuity characteristics to achieve impedance matching. By providing multiple degrees of freedom in the design, the patent makes it possible to achieve precise impedance matching even with shortened transmission lines, thereby resolving the contradiction between size reduction and matching precision.
Solution Approach 2:
The patent divides the transmission lines into multiple segments or sections with different characteristics (widths, positions, lengths) rather than using single uniform lines. This segmentation allows each section to contribute to the overall impedance transformation, enabling complex matching functions to be achieved with shorter total line lengths while maintaining manufacturing precision through modular design.
3Reliability
If multiple transmission lines are used in branch lines to enhance isolation, then isolation is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the transmission lines themselves by incorporating isolation enhancement features directly into the line structure through width variations and positional arrangements. This merging of isolation function into the existing transmission lines eliminates the need for separate dedicated isolation structures, thereby reducing device complexity while maintaining or improving isolation performance.
Solution Approach 2:
The transmission lines in the patent are designed to perform multiple functions simultaneously: signal transmission, impedance matching, and isolation enhancement. By making the transmission lines universal structures that fulfill multiple roles, the patent reduces the total number of separate components needed, thereby decreasing device complexity while maintaining high isolation performance through the multi-functional design.
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 low transmission loss and improved isolation, allowing for smaller semiconductor switches, transceivers, transmitters, and receivers while maintaining effective RF signal switching across a wide frequency range.
Implementation Method 1
the impedance of one of the plurality of branch lines as seen from the branch point is conjugately matched to the combined impedance of the main line and the rest of the plurality of branch lines as seen from the branch point
Data Source
AI summary
A semiconductor switch includes a main line, branch lines branching from the main line at the same branch point, switching devices shunt-connected between one of the branch lines and ground and operated so that the one of the branch lines is connected to and disconnected from ground, a main terminal connected to an end of the main line, and branch terminals connected to an end of one of the branch lines. The impedance of one of the branch lines, as seen from the branch point, is conjugately matched to the combined impedance of the main line and the rest of the branch lines, as seen from the branch point, the one of the branch lines transmitting an RF signal, and the rest of the branch lines blocking the RF signal.