Millimeter Wave Switch Impedance Matching via Preliminary FET Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-frequency switches operating in the millimeter wave band face issues with impedance mismatch during switching, leading to resonance within the package, which affects the reliability and cost of radar and communication apparatuses.
Innovation Solution
A high-frequency switch configuration with a matching semiconductor element that is ON during the switch-OFF state, coupled between the grounding end and the stub of the matching circuit, ensures the characteristic impedance at the connection end matches the high-frequency transmission system, reducing reflection loss and inhibiting intra-package resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional high-frequency switch configuration is used, then the switching operation is achieved, but impedance mismatch occurs during switching leading to resonance within the package
Solution Approach 1:
The matching semiconductor element is configured to be turned ON in advance during the switch-OFF state, before the actual switching operation occurs. This preliminary action establishes the correct impedance matching condition (50 ohms) at the connection end before switching takes place, preventing impedance mismatch and subsequent resonance during the switching transition.
Solution Approach 2:
The invention changes the impedance parameter at the connection end by controlling the matching semiconductor element. During the switch-OFF state, the matching semiconductor element is turned ON to transform the impedance to 50 ohms, matching the characteristic impedance of the transmission system. This parameter change eliminates impedance mismatch and prevents resonance without affecting the main switching function.
2Reliability
If the matching semiconductor element is added to prevent resonance, then impedance matching is improved, but device complexity increases
Solution Approach 1:
The matching semiconductor element serves multiple functions: it provides impedance matching during the switch-OFF state to prevent resonance, and can be integrated into the existing switch architecture. This multi-functional approach allows a single additional component to address the resonance issue without requiring multiple separate circuits or complex modifications to the switch structure.
Solution Approach 2:
The matching semiconductor element acts as an intermediary component between the switching element and the transmission system. It mediates the impedance transformation needed to match the 50-ohm characteristic impedance of the transmission system during switching operations, thereby preventing resonance without disrupting the main switching function.
3Loss of energy
If impedance matching is achieved during switch-OFF state, then reflection loss is reduced, but additional control signals are required
Solution Approach 1:
The control of the matching semiconductor element is merged with the existing control logic of the high-frequency switch. The matching element is controlled by the same control signals that govern the main switching operation, specifically being turned ON during the switch-OFF state. This merging approach reduces reflection loss without requiring entirely separate control systems.
Data Source
AI summary
A high-frequency switch operating in a millimeter wave band that includes a signal path having a λ/4 transmission path, for part of two or more branch signal paths that branch from an input connection path via a branch point; an FET, which is shunt-connected between a grounding end and the branch signal paths that are positioned between the λ/4 transmission path and a terminal end, as viewed from the branch point, and used to connect or disconnect the branch signal paths and the grounding end; an output matching circuit, which is positioned on the branch signal paths that are positioned between a terminal end and a connection point for the FET as viewed from the branch point, and includes a shunt-connected stub; and a matching FET, which is connected between the stub and the grounding end and used to connect or disconnect the stub and the grounding end in accordance with the FET's connection/disconnection.