Acoustic Wave Resonator Layout for Wideband Multiplexer Attenuation
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Solution Overview
Problem
Existing filter devices and multiplexers face challenges in achieving high attenuation characteristics over a wide bandwidth without increasing size or deteriorating Q-values, particularly when dealing with multiple frequency bands and steep pass band edges.
Innovation Solution
The implementation of a filter device with a first acoustic wave resonator and an additional circuit connected in parallel, where the electromechanical coupling coefficient of the additional circuit differs from that of the filter circuit, allowing for adjustable attenuation characteristics by varying the coupling coefficients based on the frequency band requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a plurality of additional circuits having different predetermined frequency bands are arranged to attenuate a wide frequency band, then the attenuation bandwidth is improved, but the transmission-side filter circuit is increased in size
Solution Approach 1:
The patent changes the electromechanical coupling coefficient parameter of the acoustic wave resonator in the additional circuit. By using a resonator with a different coupling coefficient than the filter circuit, the additional circuit can provide effective attenuation across a wide frequency band without requiring multiple separate circuits, thereby achieving wideband attenuation while maintaining a compact size.
2Manufacturing precision
If a capacitive element is connected in parallel to a resonator in the additional circuit to attenuate a narrow frequency band, then the attenuation precision is improved, but the transmission-side filter circuit is increased in size and the Q-value deteriorates
Solution Approach 1:
Instead of adding capacitive elements that increase size and reduce Q-value, the patent changes the fundamental parameter of the acoustic wave resonator itself - the electromechanical coupling coefficient. This parameter change enables the resonator to provide precise attenuation at specific frequencies while maintaining a compact footprint and preserving high Q-values, as the resonator's intrinsic properties are optimized rather than augmented with additional lossy components.
3Manufacturing precision
If a capacitive element is connected in parallel to a resonator in the additional circuit to attenuate a narrow frequency band, then the attenuation precision is improved, but the Q-value of the transmission-side filter circuit deteriorates
Solution Approach 1:
The patent avoids using capacitive elements that inherently introduce conductance losses and reduce Q-value. Instead, it changes the electromechanical coupling coefficient of the acoustic wave resonator, which allows precise frequency-selective attenuation to be achieved through the resonator's modified resonant characteristics. This approach maintains the high Q-value of the filter circuit because the resonator itself is designed with optimized coupling properties rather than being degraded by parallel capacitive loading.
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 compact filter devices and multiplexers with improved attenuation characteristics across a wide bandwidth, reducing insertion loss and maintaining high Q-values, thus addressing the size and performance issues of existing technologies.
Implementation Method 1
a first filter circuit that is connected to the first terminal and the second terminal, that includes a first acoustic wave resonator
Implementation Method 2
acoustic wave resonator
Implementation Method 3
an electromechanical coupling coefficient of the additional circuit is different from an electromechanical coupling coefficient of the first filter circuit
Data Source
AI summary
A filter device includes a filter circuit that is connected to terminals, is defined by a first acoustic wave resonator that has a first frequency band as a pass band, and an additional circuit that is connected in parallel to at least one first acoustic wave resonator between the terminal and the terminal. The additional circuit is defined by a second acoustic wave resonator in which an electromechanical coupling coefficient of the additional circuit is different from an electromechanical coupling coefficient of the filter circuit.