Compact RF Generator Using Self-Resonant Bifilar Toroidal Inductor

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Solution Overview

Problem

Existing RF generator circuits face challenges in producing high load voltage at high frequencies efficiently, particularly for applications like ion mobility spectrometers, where precise voltage step-up and frequency generation are critical.

Innovation Solution

The RF generator circuit employs a series resonant circuit with a bifilar toroidal dual inductor and capacitors, where the dual inductor provides a voltage step-up by resonating with a capacitive load, using a toroidal core and windings with low RF loss materials, and an active device to drive the circuit, enabling efficient high-frequency signal generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional RF generator circuits are used to produce high load voltage at high frequencies, then voltage step-up is achieved, but the circuit size becomes large and power consumption increases

Engineering Contradiction:
Improvepower consumptionVSAvoidcircuit size
Core Design Contradiction:
PowerVSVolume of stationary object

Solution Approach 1:

The patent combines the inductor and capacitor into a single integrated resonant circuit structure, where the bifilar toroidal inductor and capacitive load form a unified resonant system. This merging eliminates the need for separate voltage multiplication stages and reduces overall circuit size while maintaining efficient power operation at high frequencies

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes electrical resonance at a specific frequency (e.g., 6.78 MHz) to achieve voltage step-up. By operating the integrated resonant circuit at its resonant frequency, the system efficiently amplifies voltage without requiring large circuit components or excessive power consumption, similar to how mechanical resonance amplifies vibrations at specific frequencies

Inventive Principle:
Principle #18Mechanical vibration

2Object-generated harmful factors

If conventional inductors are used, then voltage step-up is achieved, but magnetic field radiation increases

Engineering Contradiction:
Improvemagnetic field radiationVSAvoidvoltage step-up efficiency
Core Design Contradiction:
Object-generated harmful factorsVSPower

Solution Approach 1:

The patent employs a toroidal (doughnut-shaped) inductor geometry instead of conventional straight or rectangular windings. This curved, closed-loop structure confines the magnetic field within the toroid core, preventing magnetic field radiation to the surrounding environment while maintaining the inductive properties necessary for voltage step-up in the resonant circuit

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Loss of energy

If standard wiring is used for the inductor, then construction is simple, but RF losses increase

Engineering Contradiction:
ImproveRF lossVSAvoidconstruction complexity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent uses bifilar wiring, where two insulated wires are twisted or wound together in close proximity. This composite wiring structure reduces RF losses through proximity effect optimization and improved current distribution, while the twisted pair configuration maintains relative construction simplicity and provides inherent shielding against electromagnetic interference

Inventive Principle:
Principle #40Composite materials

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 configuration achieves a high voltage step-up at high frequencies, such as several MHz, with low power consumption, while maintaining a compact size and minimizing magnetic field radiation, suitable for applications like ion mobility spectrometers.

Implementation Method 1

a series resonant circuit including a self-resonant dual inductor

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

The dual inductor is configured to provide a voltage step up of the signal of the active device

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3779429B1Compact high voltage RF generator using a self-resonant inductor
Publication Date: 2023.06.07 SMITHS DETECTION WATFORD LTD
  • EP3779429B1 patent drawingFigure 1
  • EP3779429B1 patent drawingFigure 2
  • EP3779429B1 patent drawingFigure 3

AI summary

RF generators including active devices driving series resonant circuits are described. The series resonant circuits include a self-resonant dual inductor. The RF generators can be used to drive capacitive loads.