High-Frequency Switch Circuit With Stub Lines for Better Isolation
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Solution Overview
Problem
Existing high-frequency switch circuits struggle to achieve sufficient isolation as signal frequencies increase, leading to inadequate performance in cut-off states.
Innovation Solution
The proposed high-frequency switch circuit includes a first switch connected between input and output terminals, with a second switch controlling the conduction and cut-off states of the first switch. Transmission lines are configured to function as stubs, enhancing isolation characteristics by maximizing the isolation between input and output terminals when the first switch is in a cut-off state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If signal frequency is increased, then processing capability is improved, but isolation characteristics in cut-off state deteriorate
Solution Approach 1:
The patent divides the single switch function into two switches (first switch and second switch) that operate in complementary modes. The first switch handles the primary switching function while the second switch is specifically designed to improve isolation characteristics in the cut-off state. This segmentation allows each switch to be optimized for its specific function, enabling the circuit to handle higher frequencies while maintaining reliable isolation.
Solution Approach 2:
The patent introduces transmission lines as intermediary elements between the switches and the input/output terminals. These transmission lines are specifically configured with lengths that are integral multiples of 1/4 wavelength at the operating frequency, creating impedance transformations that enhance isolation characteristics. The transmission lines act as mediators that improve the overall isolation performance without requiring changes to the switch devices themselves.
2Reliability
If isolation characteristics are improved, then signal separation is enhanced, but device complexity increases
Solution Approach 1:
The transmission lines in the patent serve multiple functions simultaneously: they provide impedance transformation for isolation enhancement, they act as signal transmission paths, and they contribute to the overall circuit compactness. By making the transmission lines perform multiple functions, the patent achieves improved isolation characteristics without adding separate isolation components, thus limiting the increase in device complexity.
Solution Approach 2:
The patent combines the isolation function with the existing switch and transmission line structure rather than adding separate isolation components. The second switch is integrated into the existing circuit topology, and its isolation function is merged with the transmission line impedance transformation. This merging approach achieves enhanced isolation while minimizing the increase in overall circuit complexity.
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 configuration improves isolation characteristics by about 6 dB compared to existing circuits, while maintaining low insertion loss, thus effectively addressing the challenge of increasing signal frequencies.
Implementation Method 1
a first transmission line, one end of the first transmission line being connected to the input terminal and an input-side terminal of the first switch; a second transmission line, one end of the second transmission line being connected to the output terminal and an output-side terminal of the first switch
Data Source
AI summary
A high-frequency switch circuit according to the present disclosure includes: an input terminal; an output terminal; a first switch connected between the input terminal and the output terminal; a first transmission line, one end of the first transmission line being connected to the input terminal and an input-side terminal of the first switch; a second transmission line, one end of the second transmission line being connected to the output terminal and an output-side terminal of the first switch; and a second switch connected between another end of the first transmission line and another end of the second transmission line, the second switch being controlled so that a conduction state and a cut-off state are exclusive to the first switch.