Duplexer Receiving Filter Capacitance Tuning for Steep Passbands

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Solution Overview

Problem

Existing duplexer technologies using multi-mode acoustic wave resonators struggle to achieve sufficient passband characteristics, especially in miniaturized mobile communication terminals with simultaneous transmission and reception capabilities.

Innovation Solution

A duplexer design incorporating a piezoelectric substrate with a receiving filter and a transmitting filter, where one resonator in the receiving filter is a multi-mode type acoustic wave resonator with a capacitance two times or more the average capacitance of other resonators, enhancing impedance matching and passband steepness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional multi-mode resonators are used in duplexers, then device miniaturization is achieved, but passband characteristics and impedance matching are insufficient

Engineering Contradiction:

Improveduplexer sizeVSAvoidpassband characteristics

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent changes the capacitance parameter of the multi-mode resonator to be two times or more the average capacitance of other resonators. This parameter change improves impedance matching and passband characteristics while maintaining the miniaturized form factor of the duplexer

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multi-mode resonators with increased capacitance are used, then impedance matching and passband steepness are improved, but device complexity increases

Engineering Contradiction:

Improveimpedance matchingVSAvoidresonator configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by making only one specific resonator in the receiving filter a multi-mode resonator with increased capacitance, while other resonators remain conventional. This localized modification improves impedance matching without requiring complete redesign of the entire filter system

Inventive Principle:

Principle #3Local quality

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 proposed duplexer achieves low loss and excellent passband characteristics in steepness, particularly on the high frequency side, thereby meeting the stringent requirements of modern mobile communication systems.

Implementation Method 1

a piezoelectric substrate, a receiving filter formed on the piezoelectric substrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

one of the resonators of the receiving filter is a multi-mode type acoustic wave resonator

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Data Source

PatentUS12289101B2Duplexer

Publication Date: 2025.04.29 SANAN JAPAN TECH CORP

AI summary

A duplexer includes a piezoelectric substrate, a receiving filter formed on the piezoelectric substrate, the receiving filter includes a plurality of resonators, and a transmitting filter formed on the piezoelectric substrate, the transmitting filter includes a plurality of resonators. One of the resonators of the receiving filter is a multi-mode type acoustic wave resonator having a capacitance that is two times or more the average capacitance of the other resonators formed on the piezoelectric substrate.