Resonator Device Series Arm Attenuation and Size Reduction
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Solution Overview
Problem
Existing resonator devices for high-frequency filters, such as those used in portable information terminals, face challenges in increasing attenuation outside the passband and reducing device size.
Innovation Solution
A resonator device configuration featuring series arm resonators with inductors and capacitors connected in parallel in some resonators, while others have no parallel components, allowing for enhanced attenuation and size reduction by adjusting antiresonance frequencies and using elastic wave resonators like SAW devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an inductor and capacitor are connected in parallel with a resonator, then design flexibility is improved, but it becomes difficult to sufficiently increase attenuation outside the passband
Solution Approach 1:
The series arm resonator device is segmented into multiple resonators (first resonator and second resonator) with different configurations. The first resonator has parallel LC components for frequency adjustment, while the second resonator is configured without parallel components to provide strong attenuation. This segmentation allows each resonator to perform its specialized function, resolving the contradiction between design flexibility and attenuation performance.
Solution Approach 2:
Different parts of the resonator device have different local qualities: the first resonator has parallel LC components for frequency tuning capability, while the second resonator has a simple structure for maximum attenuation. This local differentiation allows the system to achieve both design flexibility in frequency selection and strong attenuation in the stopband.
2Adaptability or versatility
If an inductor and capacitor are connected in parallel with a resonator, then antiresonance frequency adjustment is enabled, but device size cannot be sufficiently reduced
Solution Approach 1:
The resonator device is divided into multiple resonators with different functions. Frequency adjustment is concentrated in the first resonator with parallel LC components, while the second resonator maintains a compact structure. This segmentation allows frequency tunability without requiring all resonators to be large, thus resolving the contradiction between frequency adjustment capability and device size.
3Adaptability or versatility
If all resonators have inductors and capacitors connected in parallel, then frequency tuning capability is maximized, but attenuation performance outside passband is insufficient
Solution Approach 1:
Not all resonators have the same structure. The first resonator has parallel LC components for frequency tuning, while the second resonator has a simple structure optimized for attenuation. This local quality differentiation resolves the contradiction by assigning different functions to different parts of the system.
Solution Approach 2:
The system is segmented into resonators with different configurations. The first resonator handles frequency tuning while the second resonator handles attenuation, avoiding the need for all resonators to have complex parallel LC structures and thereby achieving both tuning capability and attenuation performance.
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 effectively increases attenuation outside the passband and reduces the size of the filter and duplexer, improving design flexibility and performance in high-frequency bands like the Rx and GPS bands.
Implementation Method 1
a first antiresonance point in a frequency range higher than a resonance frequency and a second antiresonance point in a frequency range lower than the resonance frequency are defined
Implementation Method 2
the inductance of the inductor 102 and the capacitance of the capacitor 103
Implementation Method 3
the inductance of the inductor 102 and the capacitance of the capacitor 103
Implementation Method 4
using elastic wave resonators like SAW devices
Data Source
Figure 1
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Figure 3
AI summary
A resonator device (1) includes a plurality of resonators (S1a,b;S2a,b,c;S3a,b;S4a,b) which are connected in series. An inductor (L5) and a capacitor (C2) are connected in parallel with at least one (S4b) of the plurality of resonators. At least another one (S4a) of the plurality of resonators has no inductor or capacitor connected in parallel therewith. Therefore, a sufficiently large attenuation outside the passband can be attained when the resonator device is used in a filter. Furthermore, the resonator device can be reduced in size.