FBAR Filter and Duplexer Layout With Integrated Trimming Inductors

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Solution Overview

Problem

Conventional film bulk acoustic resonator (FBAR) filters and duplexers face challenges in miniaturization and cost due to the need for separate manufacturing of resonators and high-capacity trimming inductors, leading to increased size and complexity.

Innovation Solution

The integration of multiple resonators and inductors on a single substrate, with at least two shunt resonators connected in parallel and trimming inductors of low capacity, enhances attenuation and reduces size and weight by using a series and parallel configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate resonators are manufactured and integrated on a substrate, then the filter can be assembled with individual components, but the size of the filter increases

Engineering Contradiction:

Improvemanufacturing processVSAvoidfilter size

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent merges multiple resonators and trimming inductors onto a single substrate, integrating components that were previously manufactured separately. This consolidation reduces the overall filter size while maintaining the manufacturing flexibility of individual components, directly resolving the contradiction between ease of manufacture and filter size.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The substrate serves multiple functions by simultaneously hosting resonators, trimming inductors, and providing electrical interconnections. This multi-functional approach eliminates the need for separate mounting areas for each component, reducing the total filter area while preserving manufacturing simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If wire bonding is used for connecting elements, then the filter can be assembled from separate components, but parasitic components increase and efficiency decreases

Engineering Contradiction:

Improvecomponent assemblyVSAvoidfilter efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent combines resonators and inductors into an integrated structure where electrical connections are formed through the substrate itself rather than external wire bonds. This eliminates the parasitic inductance and resistance introduced by wire bonding, improving filter efficiency while maintaining component-level manufacturing flexibility.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If high capacity trimming inductors are used for each shunt resonator, then the impedance of the filter can be resolved, but the size of the filter increases

Engineering Contradiction:

Improveimpedance matchingVSAvoidfilter size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple trimming inductors onto a single substrate in an integrated configuration. This allows the filter to achieve proper impedance matching through the combined effect of multiple smaller inductors rather than requiring one large high-capacity inductor per shunt resonator, thereby reducing the overall filter size while maintaining reliability.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If multiple high capacity trimming inductors are used in a duplexer, then transmission and reception filtering can be achieved, but the size of the duplexer increases significantly

Engineering Contradiction:

Improveduplexer functionalityVSAvoidduplexer size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent integrates multiple trimming inductors for both transmission and reception filters onto a shared substrate. This consolidation allows the duplexer to maintain full transmission and reception filtering capabilities while dramatically reducing the overall device size compared to using separate high-capacity inductors for each filter function.

Inventive Principle:

Principle #5Merging (Combining)

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 configuration allows for the miniaturization of FBAR filters and duplexers while simplifying the manufacturing process and reducing costs, with improved attenuation properties and stability.

Implementation Method 1

film bulk acoustic resonator (FBAR) filter

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

film bulk acoustic resonator

Methodology Applied

Scientific EffectAcoustic wave: Sound

Data Source

PatentUS7830226B2Film bulk acoustic resonator filter and duplexer

Publication Date: 2010.11.09 BENQ CORP

AI summary

A film bulk acoustic resonator (FBAR) filter and a duplexer are disclosed. At least one series resonator is positioned between an input port for inputting a frequency signal and an output port for outputting a frequency signal, at least two shunt resonators respectively positioned between the input and output ports and a ground, a first trimming inductor connects the at least two shunt resonators and the ground, and a second trimming inductor is positioned between the at least two shunt resonators.