MEMS Switch With Integrated Membrane RF Ground
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Solution Overview
Problem
RF MEMS switches face limitations in maintaining performance at high frequencies due to parasitic capacitances and mechanical constraints, particularly in series configuration, and struggle to integrate in parallel configurations effectively.
Innovation Solution
A microelectromechanical switch design featuring a deformable membrane of highly resistive material with an integrated RF ground that is electrically connected to the substrate RF ground, allowing for optimal RF signal guidance in both series and parallel configurations without compromising mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the membrane is made fully conductive (metal or metal-covered) to improve RF signal transmission, then electrical conductivity is improved, but parasitic capacitances increase causing frequency limitation
Solution Approach 1:
The membrane is designed with highly resistive material (local quality) rather than fully conductive material, which reduces parasitic capacitances between input and output while maintaining sufficient RF signal transmission through the resistive membrane structure
Solution Approach 2:
The RF ground track integrated into the membrane acts as an intermediary element that provides RF grounding without requiring the membrane itself to be fully conductive, thereby reducing parasitic capacitances while maintaining RF performance
2Speed
If the RF mass is placed on the substrate below the membrane to improve high frequency performance, then frequency performance is improved, but the activation surface is reduced requiring larger membrane area
Solution Approach 1:
The RF mass is moved from the substrate plane to the membrane plane (another dimension), allowing the RF mass to be positioned on the membrane surface rather than below it, thus maintaining activation surface area while achieving high frequency performance
Solution Approach 2:
The RF mass is merged with the membrane structure itself, forming an integrated membrane-RF mass assembly that maintains both the mechanical activation surface and the RF performance characteristics
3Force
If the membrane area is increased to maintain activation force, then contact force is improved, but device size increases
Solution Approach 1:
The membrane is constructed from highly resistive material with specific mechanical properties that provide high contact force (>100 μN) in a compact area, eliminating the need to increase membrane area to achieve sufficient activation force
4Reliability
If coplanar technology or microstrip technology is used to maintain characteristic impedance, then RF signal guidance is improved, but parasitic effects increase at high frequencies
Solution Approach 1:
The RF ground track integrated into the membrane serves as an intermediary grounding structure that provides RF reference potential without the parasitic effects associated with traditional coplanar or microstrip grounding structures, enabling high frequency operation (>50 GHz)
Solution Approach 2:
The grounding function is segmented from the substrate and integrated into the membrane structure itself, creating a distributed RF ground system that reduces parasitic effects compared to centralized substrate grounding
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 design maintains RF performance at high frequencies (>50 GHz), retains mechanical activation strength, improves power handling, and enables simple integration in parallel configurations, ensuring reliable signal guidance and efficient power transmission.
Implementation Method 1
an electrostatic activation means (307) arranged on the substrate, the electrostatic activation means being configured, when it is activated, to deform the deformable membrane
Data Source
Figure 1~1c
Figure 2a~3b
Figure 4~4d
AI summary
The subject of the invention is a micro-electromechanical-system (MEMS) switch (1) formed in a substrate (2) and comprising a first RF signal line (3) and a second RF signal line (4), a deformable membrane (5), an activating means (7) configured to deform the membrane (5), a substrate track, and a membrane track, the RF signal lines (3, 4) being connected by one of the membrane track and the substrate track, characterised in that a membrane RF ground (9, 10) is integrated into the membrane (5), the membrane RF ground being electrically connected to a substrate RF ground (11, 12, 3, 14), the membrane RF ground framing and being formed parallelly to at least one among the membrane track (8) and the substrate track, such that the RF ground (9, 10) closely follows the RF signal path, in order to guide the propagation of the RF signal of the first RF signal line (3) to the second RF signal line (4) when the switch is in the on state.