Acoustic Wave Multiplexer Circuit for Stopband Wave Cancellation
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Solution Overview
Problem
Acoustic wave filters with longitudinally coupled resonators face challenges in ensuring attenuation outside the pass band due to drastic phase changes of unwanted waves, making it difficult to cancel these waves effectively using traditional cancel lines.
Innovation Solution
The implementation of an additional circuit with a second acoustic wave resonator connected to the first path through a different path and grounded, which is acoustically coupled to the longitudinally coupled resonator, allows for effective cancellation of unwanted waves by generating a signal waveform that accounts for phase changes, ensuring attenuation outside the pass band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional cancel line is used to cancel unwanted waves, then the structure is simple, but attenuation outside the pass band cannot be ensured due to drastic phase changes
Solution Approach 1:
The filter is divided into a ladder filter circuit and a longitudinally coupled resonator circuit with separate functions. The ladder circuit handles passband signaling while the LCR circuit specifically targets stopband attenuation, allowing each segment to be optimized for its particular function and resolving the contradiction between structural simplicity and attenuation performance.
Solution Approach 2:
The longitudinally coupled resonator acts as an intermediary element that couples the ladder filter circuit to ground at specific points. This intermediary structure provides the necessary phase compensation and attenuation without requiring complex cancel line adjustments, thereby maintaining structural simplicity while improving reliability.
2Ease of operation
If a cancel line is used to cancel unwanted waves, then the implementation is straightforward, but it fails to account for drastic phase changes outside the pass band
Solution Approach 1:
The invention changes the operating parameters by introducing a longitudinally coupled resonator with specific acoustic wave propagation characteristics. This parameter change enables the system to naturally compensate for phase variations outside the pass band without requiring precise manual adjustment of cancel line parameters, thus maintaining ease of operation while achieving accurate phase control.
3Device complexity
If the phase of unwanted waves is not compensated, then the design is simple, but attenuation outside the pass band is insufficient
Solution Approach 1:
The longitudinally coupled resonator utilizes acoustic wave vibration and resonance phenomena to achieve phase compensation. By exploiting the natural vibrational characteristics of the acoustic waves in the LCR circuit, the design achieves effective attenuation without complex electronic phase control mechanisms, thereby maintaining design simplicity while improving reliability.
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 ensures significant attenuation of unwanted waves outside the pass band, maintaining the desired signal quality by effectively canceling unwanted waveforms, even when phase changes occur.
Implementation Method 1
a first acoustic wave resonator, and a first reflector in a propagation direction of an acoustic wave excited by the first acoustic wave resonator with respect to the first acoustic wave resonator
Implementation Method 2
The additional circuit includes a second acoustic wave resonator on an opposite side of the first acoustic wave resonator with respect to the first reflector in the propagation direction of the acoustic wave
Implementation Method 3
acoustic wave filter including a longitudinally coupled resonator
Data Source
AI summary
An acoustic wave filter includes a first filter circuit on a first path and an additional circuit connected to the first path. The first filter circuit includes a series arm resonator and a longitudinally coupled resonator. The longitudinally coupled resonator includes a first acoustic wave resonator and a first reflector. The additional circuit includes a second acoustic wave resonator on the opposite side of the first acoustic wave resonator with respect to the first reflector. The second acoustic wave resonator includes a first end connected to the first path through a second path and a second end connected to ground. The series arm resonator is connected to a portion of the first path between a connection node at which the second acoustic wave resonator is connected to the first path and the longitudinally coupled resonator.