Spin Wave RF Filter With Electric-Field Switching and Tuning

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Solution Overview

Problem

Current radiofrequency wave filters are either large, energy-intensive, or not switchable, making them inefficient for applications requiring tunable and compact designs with low energy consumption.

Innovation Solution

A filter design utilizing a spin wave guiding unit with a spatially modulated magnetostatic potential, an input element for converting radiofrequency waves to spin waves, and an output element for converting spin waves back to radiofrequency signals, along with an electrical control member to modify transmission rates and efficiencies, allowing for switchable and energy-efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If YIG crystal resonance coupling is used for filtering, then the filter can be tuned by varying electromagnet current, but the filter dimensions become large (centimeter scale) and energy consumption increases (tens to hundreds of milliamps)

Engineering Contradiction:
Improvefrequency tunabilityVSAvoidelectromagnet current consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent replaces the electromagnet-mechanical field system with an electric field system using electrodes and dielectric layers. The tuning mechanism shifts from mechanical/electromagnetic coupling to electrical field modulation, eliminating the need for high-current electromagnets while maintaining frequency selectivity through electric field interaction with the ferromagnetic material.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental operating parameters from high current (tens-hundreds of mA) to low voltage (a few volts), and from electromagnetic induction to direct electric field modulation. This parameter transformation enables frequency tuning through voltage-controlled electric fields rather than current-dependent magnetic fields, dramatically reducing energy consumption.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If YIG crystal resonance coupling is used for filtering, then the filter can be tuned, but the response time becomes slow (milliseconds order)

Engineering Contradiction:
Improvefrequency tunabilityVSAvoidfrequency response time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces the slow electromagnet magnetic field buildup with instantaneous electric field establishment. Electric fields in dielectric structures respond nearly instantaneously to voltage changes, eliminating the millisecond-scale magnetic field saturation and demagnetization delays inherent in YIG crystal systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs periodic modulation of the electric field through alternating voltage application to the electrodes, enabling rapid frequency sweeping and tuning. This periodic electric field action resonates with the ferromagnetic material's natural frequencies, achieving fast frequency modulation without the inertial delays of magnetic field systems.

Inventive Principle:
Principle #19Periodic action

3Volume of stationary object

If magnetostatic wave devices with periodic ferromagnetic film structuring are used, then the filter achieves small dimensions and robustness, but the filtering properties become fixed and non-switchable

Engineering Contradiction:
Improvefilter dimensionsVSAvoidfrequency switching capability
Core Design Contradiction:
Volume of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic control by placing electrodes that generate time-varying electric fields across the ferromagnetic material. The electric field strength and frequency can be modulated in real-time, enabling the filter's transmission characteristics to be dynamically adjusted and switched between different frequency bands, unlike the static periodic structures.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent creates a multi-functional device where the same ferromagnetic film structure serves both as the filtering medium and as the tunable element. By controlling the electric field parameters through the electrodes, a single device can perform multiple filtering functions across different frequency ranges, eliminating the need for separate fixed-frequency filters.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If external radio frequency switches are added to achieve switching function, then the filter becomes switchable, but the device complexity and dimensions increase

Engineering Contradiction:
Improveswitching capabilityVSAvoidfilter structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the switching function directly into the ferromagnetic material response to electric fields. The same material and electrode structure that provides filtering also enables switching by simply changing the electric field parameters. This integration eliminates separate switching components and their associated complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the electrode system multi-functional: it serves as both the tuning mechanism for frequency selection and as the switching mechanism for enabling/disabling filter operation. By applying different voltage patterns to the same electrodes, the filter can be tuned to different frequencies or completely switched off, consolidating multiple functions into a single control interface.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enables a compact, energy-efficient, and switchable radiofrequency filter that effectively separates desired frequency components from unwanted ones, improving upon the limitations of existing technologies by reducing size and energy consumption while maintaining tunability.

Implementation Method 1

an input element of the guiding unit, the input element being able to convert with a first efficiency, a radiofrequency electromagnetic wave into a spin wave

Methodology Applied
Scientific EffectSpin wave generation: Magnetism

Implementation Method 2

a spin wave guiding unit comprising a magnetic material, the guiding unit being arranged spatially to generate a spatially modulated magnetostatic potential, the magnetostatic potential allowing the propagation of spin waves having a frequency belonging to a first set of frequencies and preventing the propagation of spin waves having a frequency belonging to a second set of frequencies

Methodology Applied
Scientific EffectMagnetostatic wave propagation: Magnetic Field

Implementation Method 3

an output element of the guide unit, the element ent output being able to convert with a second efficiency, a spin wave into a radiofrequency output signal

Methodology Applied
Scientific EffectSpin wave to electromagnetic wave conversion: Electromagnetic Induction

Implementation Method 4

a control member capable of modifying at least one among the first efficiency, the second efficiency and the transmission rate in response to the control signal that the generation unit is able to generate, the control member comprising a layer in contact with the guide unit and two configured electrodes to allow transmission of the electrical control signal through said layer in contact with the guide unit

Methodology Applied
Scientific EffectElectrical control of magnetization: Magnetism

Data Source

PatentEP3384601B1Radiofrequency wave filter and filtering device including such a filter
Publication Date: 2019.09.18 THALES SA
  • EP3384601B1 patent drawingFigure 1
  • EP3384601B1 patent drawingFigure 2~4
  • EP3384601B1 patent drawingFigure 5~9

AI summary

The invention relates to a radiofrequency wave filter (10), including: a guide unit (15) including a magnetic material, allowing the propagation of spin waves having a frequency belonging to a first set of frequencies and preventing the propagation of spin waves having a frequency belonging to a second set of frequencies, a transmission rate being defined for the guide unit (15); an input element (20) of the guide unit (15), capable of converting, with a first efficiency, a radiofrequency electromagnetic wave into a spin wave; an output element (25) of the guide unit (15), capable of converting, with a second efficiency, a spin wave into a radiofrequency output signal; and a control member (35) capable of modifying at least one of the first efficiency, the second efficiency and the transmission rate.