Acoustic Wave Filter Layout for Lower Nonlinear Distortion
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Solution Overview
Problem
Recent advancements in mobile communication, particularly with multiband and multimode compatibility, have led to increased nonlinear distortion in filters, resulting in deterioration of reception sensitivity due to the use of acoustic wave resonators in multiplexers, especially when carrier aggregation techniques are employed.
Innovation Solution
A filter configuration is introduced where at least one series arm circuit or parallel arm circuit does not include an acoustic wave resonator, instead using a capacitance element, which reduces nonlinear distortion while maintaining characteristics similar to a basic ladder acoustic wave filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic wave resonators are used in all series arm circuits and parallel arm circuits, then the filter achieves steep pass band characteristics and low loss, but nonlinear distortion increases causing deterioration in reception sensitivity
Solution Approach 1:
The patent extracts acoustic wave resonators from specific circuits (series arm circuits at both ends or parallel arm circuits) while retaining them in other circuits. This selective removal reduces nonlinear distortion in critical paths while preserving the steep pass band characteristics and low loss properties where acoustic wave resonators are maintained.
Solution Approach 2:
The patent applies different circuit configurations to different locations within the filter structure. Series arm circuits at both ends or specific parallel arm circuits use non-acoustic wave components while other circuits use acoustic wave resonators, creating local quality differences that optimize both distortion reduction and filtering performance in specific regions.
2Reliability
If acoustic wave resonators are used in multiplexers for multiband and multimode compatibility, then the filter provides low loss and steep pass band characteristics, but nonlinear distortion occurs especially in carrier aggregation scenarios
Solution Approach 1:
The patent removes acoustic wave resonators from specific series arm circuits at both ends or from specific parallel arm circuits within the multiplexer structure. This extraction reduces harmonic distortion and intermodulation distortion while maintaining the low loss and steep pass band characteristics in other circuits where acoustic wave resonators are retained.
Solution Approach 2:
The patent implements local quality differentiation by using non-acoustic wave circuit components in specific series arm circuits at both ends or in specific parallel arm circuits, while using acoustic wave resonators in other circuits. This localized approach reduces nonlinear distortion in critical paths while preserving superior filtering characteristics in other regions.
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 proposed filter design effectively reduces nonlinear distortion, such as harmonic and intermodulation distortion, thereby improving reception sensitivity and maintaining favorable pass band characteristics, even in carrier aggregation scenarios.
Implementation Method 1
a resonance signal having a resonance frequency is obtained by causing an acoustic wave resonator to respond to an input signal
Implementation Method 2
a band pass filter having a pass band including a resonance frequency
Data Source
AI summary
A filter includes a signal path connecting an input terminal and an output terminal one or more series arm circuits on the signal path, and one or more parallel arm circuits connected to one or more nodes disposed on the signal path and a ground electrode. The one or more series arm circuits define any of a section between nodes adjacent to each other, a section between a node closest to the input terminal and the input terminal, and a section between a node closest to the output terminal and the output terminal. Among the one or more series arm circuits and the one or more parallel arm circuits, one circuit does not include any acoustic wave resonator, and another circuit includes an acoustic wave resonator.