Switch Circuit Resonant Impedance Matching for Millimeter Wave Isolation
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Solution Overview
Problem
Conventional switch circuits, particularly traveling wave type switches with FET structures, face challenges in achieving low insertion loss and high isolation characteristics in millimeter wave bands due to increased resistance with frequency, leading to suboptimal performance in wide band frequencies.
Innovation Solution
The implementation of resonant circuits connected between transmission lines and distributed constant lines in switch circuits, which resonate at predetermined frequencies when branch paths are in the OFF state, allowing impedance to be set near a reflection coefficient of 1 on the Smith chart, effectively making the branch paths appear open, thereby improving switch circuit characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traveling wave type switch with distributed constant line and FET structure is used to achieve wide band operation, then switching characteristic in wide band is improved, but insertion loss increases and isolation characteristic deteriorates at millimeter wave frequencies
Solution Approach 1:
The patent changes the impedance parameter of the distributed constant line by introducing resonant circuits. The resonant circuits are designed to resonate at specific frequencies to transform the impedance of the distributed constant line, thereby reducing insertion loss and improving isolation characteristic at millimeter wave frequencies while maintaining wide band operation capability
2Loss of energy
If resonant circuit is added to improve isolation and reduce insertion loss, then switch circuit characteristics improve, but device complexity increases
Solution Approach 1:
The patent integrates the resonant circuits within the existing switch circuit structure. The resonant circuits are nested between the distributed constant lines and the branch paths, utilizing the existing transmission line infrastructure while adding the resonant functionality. This nested configuration improves isolation and reduces insertion loss without requiring a complete redesign of the switch circuit architecture
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 reduces insertion loss to approximately 1.3 dB and enhances isolation characteristics to over 100 dB at specific frequencies, significantly improving performance compared to conventional techniques.
Implementation Method 1
a first resonant circuit connected between the first transmission line and the first distributed constant line to resonate at a predetermined frequency while the first branch path is in OFF state
Data Source
AI summary
A branch path having a transmission line and a distributed constant line includes a resonant circuit. The resonant circuit resonates at a predetermined operating frequency when the branch path is in OFF state. At this time, the distributed constant line has a predetermined impedance. Further, an impedance of a node between the resonant circuit and distributed constant line can be set on a circle of a reflection coefficient 1 near short on the Smith chart.