FBAR High-Pass Filter Layout for Antiresonance Attenuation

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Solution Overview

Problem

High pass filters using film bulk acoustic resonators (FBARs) face degradation in attenuation properties due to antiresonant frequencies occurring in lower frequency bands, leading to suboptimal performance in micro-frequency applications.

Innovation Solution

The design incorporates multiple resonant circuits with inductors and capacitors, including FBARs, where resonant frequencies are strategically positioned to compensate for antiresonant frequencies, with specific frequency relationships and placements to enhance attenuation regions and reduce insertion loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If FBARs are used to implement high pass filters, then the filters can be miniaturized and mass-produced with minimal cost, but attenuation properties are degraded due to antiresonant frequencies in lower frequency bands

Engineering Contradiction:

Improvemass production capabilityVSAvoidattenuation properties

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The filter is divided into multiple resonant circuits (first through fifth resonant circuits), each with specific inductors and capacitors configured to create distinct attenuation regions. This segmentation allows independent optimization of each circuit's frequency response to compensate for FBAR antiresonant frequencies while maintaining mass production benefits

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent strategically adjusts inductance and capacitance values in each resonant circuit to position attenuation regions at specific frequencies. By changing these electrical parameters, the filter compensates for unwanted antiresonant frequencies of FBARs while preserving the miniaturization and cost advantages

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple resonant circuits are added to compensate for antiresonant frequencies, then attenuation properties are improved, but device complexity increases

Engineering Contradiction:

Improveattenuation propertiesVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple resonant circuits are merged into a single integrated filter structure where the first through fifth resonant circuits work together in parallel and series configurations. This combining approach achieves complex frequency compensation functionality while maintaining a compact unified design that does not excessively increase overall device complexity

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If resonant frequencies are strategically positioned to compensate for antiresonant frequencies, then insertion loss is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveinsertion loss performanceVSAvoidfrequency tuning accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The resonant frequencies of the five resonant circuits are pre-calculated and pre-positioned during the design phase to compensate for known FBAR antiresonant frequencies. This preliminary frequency planning ensures that attenuation regions are correctly positioned before manufacturing, reducing the need for post-fabrication tuning and lowering manufacturing precision requirements

Inventive Principle:

Principle #10Preliminary action

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 improves attenuation properties and insertion loss performance, ensuring effective filtering with rapid pass band and rejection band differences, achieving excellent attenuation and minimal insertion loss.

Implementation Method 1

a first acoustic resonator having a first resonant frequency and a first antiresonant frequency; and a second acoustic resonator having a second resonant frequency and a second antiresonant frequency

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

attenuation regions respectively formed by the first resonant circuit, the second resonant circuit, and the third resonant circuit are arranged in lower frequency regions than attenuation regions respectively formed by the fourth resonant circuit and the fifth resonant circuit

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS10784839B2High pass filter

Publication Date: 2020.09.22 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

A high pass filter includes: a first resonant circuit including an inductor and a capacitor in parallel between first and second terminals; a second resonant circuit including an inductor and a capacitor in series between a first end of the first resonant circuit and a ground; a third resonant circuit including an inductor and a capacitor in series between a second end of the first resonant circuit and the ground; a fourth resonant circuit disposed between the first end of the first resonant circuit and the first terminal, and including a first acoustic resonator; and a fifth resonant circuit disposed between the second end of the first resonant circuit and the second terminal, and including a second acoustic resonator. Attenuation regions respectively formed by the first, second, and third resonant circuits are arranged in lower frequency regions than attenuation regions respectively formed by the fourth and fifth resonant circuits.