Conductively Coupled RF Filter Tuning for Multi-Stopband Rejection

Solution Overview

Problem

Existing RF communication systems face challenges in achieving strong harmonic rejection with filters that require multiple variable components, leading to increased complexity and space requirements.

Innovation Solution

A filter circuit with a plurality of capacitances and inductances, including a single variable reactance that is conductively coupled with other components, allowing a change in the variable reactance to alter the resonant frequencies of multiple resonant modes without requiring multiple separate variable inductances or capacitances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple variable inductances or capacitances are used to achieve strong harmonic rejection, then filtering performance is improved, but device complexity and space requirements increase

Engineering Contradiction:

Improveharmonic rejection performanceVSAvoidfilter circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A single variable reactance element is designed to control multiple resonant modes simultaneously, allowing one component to perform the function that would traditionally require multiple variable components. The variable reactance is coupled to multiple LC resonant circuits, enabling unified control of multiple stopbands through a single tuning mechanism.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Multiple independent variable components are merged into a single variable reactance element that controls all resonant modes. The filter circuit combines multiple LC resonant circuits with a shared variable reactance, merging what would be separate tuning functions into one unified control system.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple variable inductances or capacitances are used to achieve strong harmonic rejection, then filtering performance is improved, but space requirements increase

Engineering Contradiction:

Improveharmonic rejection performanceVSAvoidfilter circuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

A single variable reactance element is designed to control multiple resonant modes simultaneously, allowing one component to perform the function that would traditionally require multiple variable components. The variable reactance is coupled to multiple LC resonant circuits, enabling unified control of multiple stopbands through a single tuning mechanism.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Multiple independent variable components are merged into a single variable reactance element that controls all resonant modes. The filter circuit combines multiple LC resonant circuits with a shared variable reactance, merging what would be separate tuning functions into one unified control system.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If a single variable reactance is used to control multiple resonant modes, then device complexity is reduced, but the ability to independently tune each resonant frequency is limited

Engineering Contradiction:

Improvefilter circuit complexityVSAvoidindependent tuning capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The filter circuit is designed with dynamic coupling between the variable reactance and multiple resonant modes, allowing the system to adaptively adjust multiple resonant frequencies through a single variable element. The conductive coupling enables the variable reactance to influence multiple LC circuits, creating a dynamically tunable system that maintains adaptability while reducing component count.

Inventive Principle:

Principle #15Dynamics

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 solution enables efficient harmonic notch filtering by allowing a single variable reactance to change the frequencies of multiple stopbands, reducing complexity and space requirements while maintaining effective harmonic rejection.

Implementation Method 1

a plurality of resonant modes that each correspond to resonance at a resonant frequency between the variable reactance and one or more of the plurality of inductances and one or more of the plurality of capacitances

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS12323121B2Tunable filtering using conductively coupled resonances

Publication Date: 2025.06.03 SKYWORKS SOLUTIONS INC

AI summary

A filter circuit including a plurality of capacitances and a plurality of inductances including one variable reactance that is either an inductance or a capacitance. The filter circuit has a plurality of resonant modes that each correspond to resonance at a resonant frequency between the variable reactance and one or more of the plurality of inductances and one or more of the plurality of capacitances. The variable reactance is conductively coupled with one or more other inductances and capacitances of the pluralities of inductances and capacitances such that a change in the variable reactance causes a change in a resonant frequency of more than one of the plurality of resonant modes. Front-end modules and wireless communication devices incorporating such a filter circuit and a method using such a filter circuit are also described.