Tunable Dielectric Filter With Piezoelectric Thickness Control

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Solution Overview

Problem

Current RF system designs face challenges in optimizing insertion loss for specific frequency bands while maximizing rejection of unwanted frequencies, particularly as they transition to millimeter wave frequencies, relying heavily on active signal processing and discrete components.

Innovation Solution

A filter apparatus comprising alternating dielectric layers with thin-film metal layers and piezoelectric materials that adjust thickness in response to control voltage, allowing for tunable rejection notches and enhanced image rejection through material composition and geometry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If active signal processing and discrete components are used to optimize insertion loss and frequency rejection, then filtering performance is improved, but device complexity increases

Engineering Contradiction:

Improvefiltering performanceVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The filter is segmented into multiple alternating dielectric layers with different permittivity values, where each layer pair creates a specific filtering effect. This segmentation allows complex filtering functionality to be achieved through simple material layering rather than complex active circuitry.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite dielectric structures with alternating layers of different materials (e.g., silicon dioxide and silicon nitride) to achieve frequency-dependent filtering. The composite structure exploits the different electromagnetic properties of each material to create the desired filtering response without active components.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If fixed filter design is used, then manufacturing is simplified, but adaptability to different frequency requirements is reduced

Engineering Contradiction:

Improveease of manufactureVSAvoidtunability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The filter incorporates piezoelectric actuators that can dynamically adjust the physical thickness of dielectric layers in response to control voltages. This dynamic adjustment capability allows the filter to be tuned to different frequency requirements while maintaining a relatively simple fixed manufacturing process for the base structure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention enables parameter changes by using piezoelectric materials that alter the physical dimensions (thickness) of dielectric layers when voltage is applied. This changes the electrical characteristics of the filter, allowing adaptation to different frequency requirements without remanufacturing the entire device.

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

The solution achieves improved insertion loss and frequency rejection by dynamically tuning the filter's response to specific frequencies, reducing reliance on active processing and enhancing performance across millimeter wave frequencies with minimal insertion loss.

Implementation Method 1

one or more piezoelectric plates configured to apply a select amount of pressure to the plurality of dielectric layers to cause at least one of the one or more first dielectric layers or the one or more second dielectric layers to compress in response to a control voltage

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the first dielectric material of the one or more first dielectric layers may be a first piezoelectric material, the first piezoelectric material may be configured to adjust a physical thickness of the one or more first dielectric layers upon application of a control voltage

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

Methodology Applied

Scientific EffectElectromagnetic filtering: Filter (electronic)

Data Source

PatentUS11670828B1Dielectric and thin film floating metal stacking for embedded tunable filtering of high frequency signals

Publication Date: 2023.06.06 ROCKWELL COLLINS INC

AI summary

A filter apparatus is disclosed. The filter apparatus may include a plurality of dielectric layers. The plurality of dielectric layers may include one or more first dielectric layers formed of a first dielectric material and one or more second dielectric layers formed of a second dielectric material. The second dielectric material of the one or more second dielectric layers being different than the first dielectric material of the one or more first dielectric layers. The filter apparatus may further include one or more thin-film metal layers arranged between at least one dielectric layer of the plurality of dielectric layers and an additional dielectric layer of the plurality of dielectric layers.