Reconfigurable RF Filter Using Commutated FBAR Resonators

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current RF filter technologies face challenges in achieving efficient reconfigurability and miniaturization, particularly in next-generation mobile radios, due to high fabrication complexity and power consumption, which limits their ability to adapt to varying data rates and frequency bands.

Innovation Solution

A reconfigurable RF filter using periodically commutated thin-film bulk-acoustic resonators (FBARs) with a double-pole, double-throw (DPDT) switch, allowing for bandpass or bandstop responses, enabling real-time adjustment of center frequency and bandwidth with minimal additional design effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional FBAR ladder filters are used for multi-frequency operation, then frequency adaptability is improved, but fabrication complexity increases

Engineering Contradiction:

Improvefrequency adaptabilityVSAvoidfabrication complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent employs dynamic switching of identical FBAR resonators through DPDT switches controlled by clock signals, allowing the filter to reconfigure its frequency response in real-time. This dynamic approach replaces static multi-frequency FBAR design with a time-variant system that achieves frequency adaptability without requiring different resonator structures for each frequency band.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The filter utilizes periodic commutation of resonators through clocked DPDT switches, where switches alternate between connecting different resonators to the signal path at regular intervals. This periodic switching creates time-variant filtering characteristics that enable multi-frequency operation using identical resonators, eliminating the need for complex multi-frequency FBAR fabrication.

Inventive Principle:

Principle #19Periodic action

2Adaptability or versatility

If reconfigurable filter capabilities are added to adapt to varying data rates and frequency bands, then adaptability is improved, but device complexity increases

Engineering Contradiction:

ImprovereconfigurabilityVSAvoiddesign complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The same FBAR resonators and switching infrastructure serve multiple functions: they provide both bandpass and bandstop filtering modes, support multiple frequency bands through commutation, and enable real-time reconfiguration. The DPDT switches and clock control system universally manage all reconfiguration tasks, eliminating the need for separate control circuits for each filtering mode or frequency band.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines bandpass and bandstop filtering capabilities within a single filter architecture by using the same resonators and switching network. The DPDT switches can configure the resonators to provide either passband or stopband responses, merging multiple filter functions into one unified structure that reduces overall design complexity compared to implementing separate filters for each mode.

Inventive Principle:

Principle #5Merging (Combining)

3Volume of moving object

If miniaturization is pursued for chip-sized systems, then device size is reduced, but filtering performance may deteriorate

Engineering Contradiction:

Improvefilter sizeVSAvoidfiltering performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The filter is divided into multiple identical resonator units that can be independently switched and configured. Each resonator segment contributes to the overall filtering performance, and their combined effect through periodic commutation achieves superior filtering characteristics. This segmented approach allows compact packaging of multiple functional elements while maintaining individual resonator performance standards.

Inventive Principle:

Principle #1Segmentation

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 provides a compact, low-power, and adaptive RF filtering capability with sharp rejection and low insertion loss, enabling efficient communication across multiple frequency bands and improving interference rejection in mobile devices.

Implementation Method 1

at least two electromechanical resonators having a same resonant frequency

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

thin-film bulk-acoustic resonators (FBARs) on the same resonance frequency

Methodology Applied

Scientific EffectBulk acoustic wave resonance:

Implementation Method 3

a double-pole, double-throw (DPDT) switch periodically modulating two thin-film bulk-acoustic resonators (FBARs) on the same resonance frequency

Methodology Applied

Scientific EffectPeriodic commutation:

Implementation Method 4

each resonator includes an electromechanical resonator or a resonant circuit... each resonator comprises a piezoelectric layer

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11329355B2Reconfigurable filter based on commutation of single frequency resonators

Publication Date: 2022.05.10 NORTHEASTERN UNIV (US)

AI summary

Adaptive RF filters based on modulated resonators are provided. The filter architecture is based on time-interleaved commutation of passive RF resonators. The architecture can behave as a two-port filter network, with a fully tunable instantaneous filter bandwidth. The filters are applicable as miniaturized, environment-aware RF signal processing components and can be used in mobile communications.