RF Micro Switch With High Permittivity Dielectric
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Solution Overview
Problem
Current micro-switches for radiofrequency and microwave systems face challenges in achieving high switching speeds, handling RF power greater than ten watts, broadband operation up to 18 GigaHertz, low compactness, and extended lifetimes while maintaining low manufacturing costs and high reliability.
Innovation Solution
A capacitor-type micro-switch structure with a high permittivity dielectric material, such as PZT, and a conductive membrane made from materials like titanium-tungsten alloy and aluminum, supported by conductive pillars, is used. The dielectric material is deposited on a control electrode with a specific shape to maximize capacitance and withstand RF power, and the membrane is designed to deform and return to its initial state efficiently, ensuring optimal switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional dielectric materials are used in micro-switches, then manufacturing costs are reduced, but switching speed and RF power handling capability are limited
Solution Approach 1:
The patent changes the dielectric parameter by using materials with high relative permittivity (greater than one hundred), which fundamentally alters the capacitance characteristics and enables faster switching speeds and higher RF power handling while maintaining compatibility with existing manufacturing processes
Solution Approach 2:
The patent employs composite structures combining high permittivity dielectric materials with conductive layers and vacuum gaps, creating a multi-material system that achieves superior performance in switching speed and power handling while remaining manufacturable through established techniques
2Power
If the membrane is designed to withstand high RF power, then power handling is improved, but switching speed decreases
Solution Approach 1:
The patent applies local quality by creating different structural characteristics in different regions: the membrane has specific properties for power handling while the vacuum gap region provides low capacitance for fast switching, allowing each region to optimize its local function without compromising the other
Solution Approach 2:
The patent introduces a vacuum gap dimension between the membrane and control electrode, creating a three-dimensional structure that separates the power handling function (membrane) from the switching function (vacuum gap capacitance), enabling both high power and fast switching simultaneously
3Area of moving object
If the micro-switch area is reduced for compactness, then integration density improves, but RF power handling capability decreases
Solution Approach 1:
The patent uses a flexible membrane structure that can be made very thin, allowing the switch to occupy minimal area while the membrane's material properties and the vacuum gap enable it to withstand high RF power densities, thus achieving compactness without sacrificing power handling
4Reliability
If high permittivity dielectric material is used, then capacitance ratio Con/Coff improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces the vacuum gap as an intermediary element between the membrane and control electrode. This vacuum gap acts as a mediator that defines the Coff capacitance, while the high permittivity dielectric on the control electrode defines the Con capacitance, allowing precise control of the capacitance ratio through the vacuum gap thickness rather than relying solely on dielectric layer precision
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 solution enhances radiofrequency and microwave performance by increasing the operating frequency band, supporting high RF power, and improving switching speed and mechanical stress resistance, leading to longer lifetimes and reduced manufacturing costs.
Implementation Method 1
The layer of dielectric material has a high relative permittivity greater than one hundred
Implementation Method 2
the application of an activation voltage under the membrane causes it to pass from an off, open state, to an on, closed state
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3a~4b
AI summary
The invention relates to a micro switch structure comprising: a substrate (1) covered by a passivation layer (2), a first signal line LS-IN and a second signal line LS-OUT being each located in the extension of the other and separated by a switching region (10); a control electrode (3) arranged in said region, a frequency-invariant dielectric material (4) with high relative permittivity being arranged on the control electrode such that the control electrode is wider on both sides and in the orthogonal direction, between the two signal lines, and the dielectric overlaps on both sides of the control electrode and lies on the passivation layer; and parallel mass lines arranged symmetrically either side of the signal lines and on a topological level separated from that of the signal lines by at least one insulating layer in a material different from that of the passivation layer.