Acoustic Wave Multiplexer Filter With Asymmetric Resonator Capacitance

Solution Overview

Problem

Existing acoustic wave filters experience degraded impedance convergence levels when coupled with other filters by common connection, leading to deteriorated return loss characteristics.

Innovation Solution

The acoustic wave filter design includes a longitudinally coupled resonator with input-side and output-side resonators having different electrostatic capacitances, and the use of interdigital transducers (IDT) electrodes with specific finger configurations to maintain impedance convergence while allowing for impedance matching with fewer components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the acoustic wave filter is coupled with other filters by common connection, then the filter can be used in multiplexer configurations, but the convergence level of impedance deteriorates and return loss characteristic worsens

Engineering Contradiction:

Improvemultiplexer configuration capabilityVSAvoidimpedance convergence level

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by making the resonators asymmetric in their electrical characteristics. Specifically, the input-side resonator and output-side resonator are designed with different electrostatic capacitances, creating localized electrical property differences that optimize impedance matching at the common terminal while maintaining overall system functionality in multiplexer configurations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the electrical parameters of the resonators by designing them with different electrostatic capacitances. This parameter differentiation between input-side and output-side resonators allows the filter to maintain proper impedance convergence when coupled with other filters through common connection, resolving the deterioration issue while preserving multiplexer adaptability.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the acoustic wave filter is coupled with other filters by common connection, then the filter can be used in multiplexer configurations, but the return loss characteristic deteriorates

Engineering Contradiction:

Improvemultiplexer configuration capabilityVSAvoidreturn loss characteristic

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by making the resonators asymmetric in their electrical characteristics. Specifically, the input-side resonator and output-side resonator are designed with different electrostatic capacitances, creating localized electrical property differences that optimize impedance matching at the common terminal while maintaining overall system functionality in multiplexer configurations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the electrical parameters of the resonators by designing them with different electrostatic capacitances. This parameter differentiation between input-side and output-side resonators allows the filter to maintain proper impedance convergence when coupled with other filters through common connection, resolving the deterioration issue while preserving multiplexer adaptability.

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

This design improves impedance convergence and reduces the need for additional matching elements, enhancing the return loss characteristic in carrier aggregation scenarios.

Implementation Method 1

The one or more input-side resonators and the one or more output-side resonators each include an interdigital transducer (IDT) electrode

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a longitudinally coupled resonator coupled between the first input terminal and the first output terminal

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS12537509B2Acoustic wave filter and multiplexer

Publication Date: 2026.01.27 MURATA MFG CO LTD

AI summary

An acoustic wave filter includes a first input terminal and a first output terminal, and a longitudinally coupled resonator coupled between the first input terminal and the first output terminal. The longitudinally coupled resonator includes one or more input-side resonators coupled to the first input terminal and one or more output-side resonators coupled to the first output terminal. A total electrostatic capacitance of the one or more input-side resonators is less than a total electrostatic capacitance of the one or more output-side resonators.