MEMS Tunable Reactance Device Non-Contact Electrostatic Actuation

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Solution Overview

Problem

Existing MEMS tunable capacitors and inductors with contacting surfaces suffer from reliability issues such as sticking, dielectric charging, and performance degradation due to changing impedance and restoring forces, limiting their use in wireless devices for maintaining signal integrity across a range of frequencies.

Innovation Solution

A tunable reactance device with a microelectromechanical structure supported on a substrate, featuring a conductive material and a driver that moves the structure using electrostatic force, allowing for changes in inductance and capacitance without physical contact, thereby maintaining low loss and high quality factor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If contacting surfaces are used in MEMS tunable capacitors and inductors, then tuning functionality is achieved, but reliability deteriorates due to sticking, dielectric charging, and performance degradation

Engineering Contradiction:

Improvetuning functionalityVSAvoiddevice reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent removes the contacting surfaces from the MEMS tunable capacitor and inductor structures. By extracting the problematic contact interfaces, the invention eliminates stiction and dielectric charging issues while preserving the essential tuning capability through non-contact variable capacitance mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces mechanical contacting surfaces with a field-based tuning mechanism. Instead of relying on physical contact between moving parts, the invention uses electric field modulation to achieve variable capacitance and inductance, thereby eliminating mechanical wear and sticking problems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If contacting surfaces are used to achieve tuning, then reactance adjustment is possible, but performance degradation occurs due to changing impedance and restoring forces

Engineering Contradiction:

Improvereactance adjustmentVSAvoidimpedance stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent substitutes mechanical contact-based tuning with an electric field-based tuning mechanism. This replacement stabilizes impedance characteristics by eliminating the variability introduced by mechanical contact resistance and restoring force changes, while maintaining full reactance adjustment capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If contacting surfaces are used in tunable reactance devices, then tuning range is achieved, but loss increases and quality factor decreases

Engineering Contradiction:

Improvetuning rangeVSAvoiddevice loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts the contacting surfaces that cause energy loss through friction and contact resistance. By removing these loss-generating interfaces, the invention maintains wide tuning range while significantly reducing energy loss and improving quality factor.

Inventive Principle:

Principle #2Taking out (Extraction)

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 device provides fast switching, repeatable, and variable reactance with minimal physical contact, enhancing signal integrity and reducing power consumption in wireless devices by allowing for a wider tuning range and design flexibility.

Implementation Method 1

a driver configured to move the MEM structure with respect to the substrate upon application of an electrostatic force to the driver

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS10388462B2Tunable reactance devices, and methods of making and using the same

Publication Date: 2019.08.20 DUEWEKE MICHAEL J

AI summary

A tunable reactance device and methods of manufacturing and using the same are disclosed. The tunable reactance device includes a substrate, a microelectromechanical (MEM) structure supported on the substrate and comprising a conductive material, and a driver configured to move the MEM structure with respect to the substrate upon application of an electrostatic force to the driver. A gap between the MEM structure and the substrate is maintained when the driver moves the MEM structure. The tunable reactance device has (i) a first reactance and a first electromagnetic field topology when the electrostatic force is applied to the driver and (ii) a different reactance and a different electromagnetic field topology when a different electrostatic force is applied to the driver.