Acoustic Wave Filter Topology for Wideband and Multiband Responses

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Solution Overview

Problem

Current filter circuits with acoustic wave resonators are limited in achieving wideband, multiband, and complex filtering responses due to restrictions in coupling coefficients and transmission zero positions, which hinders their performance in advanced communication systems.

Innovation Solution

The transversal configuration of acoustic wave resonators, where all resonators are electrically connected to both input and output ports, allowing for flexible design of transfer functions, enabling wideband, multiband, and complex transmission zero responses without dependency on piezoelectric material coupling coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional ladder or lattice filter configurations are used with acoustic wave resonators, then the filter structure is well-defined and manufacturable, but the filter bandwidth is limited by the coupling coefficient of the piezoelectric material and transmission zero positions are predefined

Engineering Contradiction:

Improvefilter response design flexibilityVSAvoidfilter configuration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent inverts the conventional filter topology by arranging resonators in a transversal configuration where all resonators are connected in parallel between input and output ports, rather than the series-parallel ladder structure. This inversion allows the filter response to be determined by individual resonator characteristics rather than coupling coefficients, achieving wideband and multiband responses with arbitrary transmission zero positions

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from the traditional series-connected ladder topology to a parallel-connected transversal topology, representing a dimensional change in the circuit architecture. This topological transformation enables independent control of each resonator's contribution to the filter response, providing design flexibility for wideband, multiband, and complex filtering characteristics

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Speed

If the filter bandwidth is increased beyond conventional limits, then advanced communication system requirements are met, but the coupling coefficient constraints of piezoelectric materials become limiting

Engineering Contradiction:

Improvesignal processing speedVSAvoidbandwidth adaptability

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameter determining filter bandwidth from the coupling coefficient (material property) to the individual resonator frequencies and impedances (circuit parameters). By controlling resonator characteristics rather than relying on piezoelectric coupling, the filter achieves wideband and multiband responses that are not constrained by material coupling limits

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If more external components are added for trimming and tuning, then filter performance can be optimized, but the device size increases and miniaturization is hindered

Engineering Contradiction:

Improvefilter performance precisionVSAvoidfilter circuit size

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The patent enables the filter to achieve precise performance through the inherent characteristics of the resonators themselves, without requiring external trimming components. The transversal configuration allows direct synthesis from polynomial transfer functions, and resonator parameters can be adjusted through design rather than physical trimming, reducing the need for additional external components

Inventive Principle:

Principle #25Self-service

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 enables miniaturization, reduced component usage, tunable filtering, and direct synthesis from polynomial transfer functions, facilitating the implementation of advanced filter responses in future communication systems.

Implementation Method 1

filter circuits with acoustic wave resonators... bulk acoustic wave (BAW) or surface acoustic wave (SAW) resonators... the coupling coefficient of the piezoelectric material

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

acoustic wave resonators... filter response can be synthesized... frequency-selective filter response

Methodology Applied

Scientific EffectAcoustic wave resonance: Resonance

Data Source

PatentUS10873318B2Filter circuits having acoustic wave resonators in a transversal configuration

Publication Date: 2020.12.22 QORVO US INC

AI summary

Filter circuits having acoustic wave resonators in a transversal configuration are disclosed. In the transversal configuration, the acoustic wave resonators are arranged transverse to an input and output port of the filter circuit. As such, all the acoustic wave resonators of the filter circuit are connected to the input port and connected to the output port. In the transversal configuration, the filter circuit can be designed for any transfer function without being restricted to a coupling coefficient of a piezoelectric material used in the acoustic wave resonators. In this regard, the filter circuit can achieve very wideband filter responses, multiband responses, and/or responses with arbitrary position of transmission zeros. The filter circuit having the transversal configuration can also be designed for complex transmission zeros for phase equalization.