Variable Inductor Digital Phase Shift Circuit for Impedance Matching

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Solution Overview

Problem

Existing digital phase shift circuits struggle to dynamically change phase shift amounts while maintaining impedance matching due to the difficulty in achieving variable inductance.

Innovation Solution

Incorporation of a variable inductor circuit with a fixed inductor and a first variable inductor connected in series, allowing for dynamic changes in inductance to achieve desired phase shift characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If only capacitor capacitance is changed to achieve desired phase shift characteristics, then phase shift amount can be adjusted, but impedance matching cannot be maintained

Engineering Contradiction:
Improvephase shift amount adjustmentVSAvoidimpedance matching
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies parameter changes by simultaneously adjusting both capacitance (through switchable capacitor connections) and inductance (through the variable inductor circuit with switchable parallel lines) to maintain impedance matching while achieving desired phase shift characteristics. This resolves the contradiction by changing multiple parameters together rather than only capacitance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamic adjustment capability through electronic switches that can change the circuit configuration in real-time. The variable inductor circuit with switchable parallel lines allows dynamic modification of inductance values, enabling the system to adaptively maintain impedance matching while adjusting phase shift amount.

Inventive Principle:
Principle #15Dynamics

2Reliability

If a variable inductor is introduced to maintain impedance matching during phase shift adjustment, then both phase shift characteristics and impedance matching can be achieved, but device complexity increases

Engineering Contradiction:
Improveimpedance matchingVSAvoidcircuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the inductor into multiple parallel lines with different inductance values, where each line can be independently switched. This segmentation allows the variable inductor function to be implemented using planar conductor patterns rather than a single complex three-dimensional structure, thereby reducing overall device complexity while maintaining the required functionality.

Inventive Principle:
Principle #1Segmentation

3Extent of automation

If a digital phase shift circuit is designed with switchable capacitors to dynamically change phase shift amount, then dynamic phase adjustment is achieved, but it becomes difficult to maintain both phase shift characteristics and impedance matching

Engineering Contradiction:
Improvedynamic phase shift controlVSAvoidimpedance matching
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The patent implements dynamic adjustment capability through electronic switches that can change the circuit configuration in real-time. The variable inductor circuit with switchable parallel lines allows dynamic modification of inductance values, enabling the system to adaptively maintain impedance matching while adjusting phase shift amount.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies parameter changes by simultaneously adjusting both capacitance (through switchable capacitor connections) and inductance (through the variable inductor circuit with switchable parallel lines) to maintain impedance matching while achieving desired phase shift characteristics.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4641927A1Digital phase circuit
Publication Date: 2025.10.29 FUJIKURA LTD
  • EP4641927A1 patent drawingFigure 1
  • EP4641927A1 patent drawingFigure 2
  • EP4641927A1 patent drawingFigure 3~4

AI summary

A digital phase shift circuit includes a variable inductor circuit in which a fixed inductor and a first variable inductor are connected in series.