RF Resonant Path Filter With Phase Shift for Impedance Band Control

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Solution Overview

Problem

Existing radio communication technologies face challenges in efficiently filtering radio signals to improve signal-to-noise ratio within specific frequency ranges, as current filter designs lack flexibility and effectiveness in managing impedance across varying frequency bands.

Innovation Solution

The proposed circuitry includes a first and second resonant radio frequency conductive paths, an internode path, a shunt resonant element, and a phase shift element. This configuration allows for a relative phase shift between the paths, enabling the circuit to provide a lower impedance path for a narrower frequency band and a higher impedance path for wider bands, effectively acting as a band-stop or band-pass filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a filter is designed to provide low impedance for a specific frequency band, then the signal-to-noise ratio is improved, but the impedance control for adjacent frequency bands becomes more complex

Engineering Contradiction:
Improvesignal-to-noise ratioVSAvoidimpedance control complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The filter is divided into multiple resonant circuits, each responsible for specific frequency bands. The first resonant circuit handles the first frequency band while the second resonant circuit handles the second frequency band, allowing independent optimization of impedance characteristics for each band without affecting the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a third dimension to the traditional two-resonator filter by adding a coupled resonant circuit with multiple coupling mechanisms. This additional dimension provides extra degrees of freedom for impedance control, enabling simultaneous optimization for multiple frequency bands through different coupling paths.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the filter uses multiple resonant circuits to achieve frequency selectivity, then the filtering effectiveness is improved, but the device complexity increases

Engineering Contradiction:
Improvefiltering effectivenessVSAvoidcircuit structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple resonant circuits into a unified filter structure where the first and second resonant circuits are coupled through a shared coupled resonant circuit. This merging allows the circuits to work together synergistically, achieving enhanced filtering effectiveness while sharing common components and reducing overall complexity compared to separate independent circuits.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupled resonant circuit serves multiple functions simultaneously: it acts as a resonant element for frequency selection, provides coupling between the first and second resonant circuits, and enables impedance transformation. This multi-functionality reduces the need for additional separate components, thereby improving filtering effectiveness without proportionally increasing complexity.

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

3Manufacturing precision

If the filter is designed with fixed impedance characteristics, then the manufacturing precision is improved, but the adaptability to different frequency ranges is reduced

Engineering Contradiction:
Improveimpedance characteristic precisionVSAvoidfrequency range adaptability
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent employs variable capacitors in both the first and second resonant circuits, allowing the resonant frequencies and impedance characteristics to be dynamically adjusted. This dynamic capability enables the filter to adapt to different frequency ranges while maintaining precise impedance control through coordinated adjustment of the variable capacitors.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The filter design incorporates variable capacitors that allow continuous adjustment of capacitance values, thereby changing the resonant frequencies and impedance characteristics of the resonant circuits. This parameter change capability provides adaptability to different frequency ranges while maintaining manufacturing precision through controlled adjustment mechanisms.

Inventive Principle:
Principle #35Parameter changes

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 described circuitry effectively enhances the signal-to-noise ratio by selectively filtering out specific frequency ranges, improving the performance of radio communication systems by providing a flexible and efficient frequency management solution.

Implementation Method 1

a first resonant radio frequency conductive path comprising a first transmission line between a first node and a third node; a second resonant radio frequency conductive path comprising a second transmission line between a second node and the third node

Methodology Applied
Scientific EffectElectromagnetic wave propagation: Electromagnetic Induction

Implementation Method 2

a shunt resonant element coupled to the third node and shared by the first resonant radio frequency conductive path and the second resonant radio frequency conductive path

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 3

a phase shift element for introducing a relative phase shift to the first resonant radio frequency conductive path relative to the second resonant radio frequency conductive path

Methodology Applied
Scientific EffectPhase shift:

Data Source

PatentEP3975330B1Radio communications
Publication Date: 2025.01.22 NOKIA TECHNOLOGIES OY
  • EP3975330B1 patent drawingFigure 1A~3B
  • EP3975330B1 patent drawingFigure 4~5
  • EP3975330B1 patent drawingFigure 6A~7

AI summary

Circuitry comprising: a first resonant radio frequency conductive path between a first node and a third node; a second resonant radio frequency conductive path between a second node and the third node; an internode radio frequency conductive path between the first node and the second node; a shunt resonant element coupled to the third node and shared by the first resonant radio frequency conductive path and the second resonant radio frequency conductive path; and a phase shift element for introducing a relative phase shift to the first resonant radio frequency conductive path relative to the second resonant radio frequency conductive path.