Acoustic Wave Filter Common-Ground Layout for Steep Attenuation
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Solution Overview
Problem
Conventional acoustic wave filter devices face challenges in reducing size while maintaining effective attenuation outside the pass band due to the need for multiple ground terminals, which increases device size and complexity.
Innovation Solution
The proposed solution involves a configuration where a parallel arm resonator connects the ground to a transmission path, with multiple longitudinally coupled resonance devices on a shared substrate, utilizing a common ground connection for all resonators to enhance attenuation by combining inductance components, thereby reducing the device size and improving attenuation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If grounds connected to each longitudinally coupled resonance device are isolated and independently disposed, then attenuation amount outside the pass band is improved, but the number of ground terminals increases and device size cannot be reduced
Solution Approach 1:
The patent merges multiple independent ground connections into a single common ground terminal. The first and second longitudinally coupled resonance devices share a common ground terminal, eliminating the need for separate ground terminals. This combining approach maintains the isolation benefit for attenuation while reducing the total number of ground terminals, thus resolving the contradiction between improved attenuation and reduced device complexity.
2Object-affected harmful factors
If multiple ground terminals are provided for isolating grounds of resonance devices, then attenuation characteristics are improved, but device size increases
Solution Approach 1:
The patent combines multiple ground terminals into a single common ground terminal that serves multiple longitudinally coupled resonance devices. This merging of ground connections reduces the area occupied by ground terminals and their associated wiring, thereby reducing the overall device size while maintaining effective attenuation characteristics through the shared ground reference.
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 achieves a small-sized acoustic wave filter device with improved attenuation outside the pass band and steep bandpass characteristics, while maintaining isolation in the pass band, by effectively utilizing inductance components and shared ground connections.
Implementation Method 1
at least one acoustic wave resonator provided on a substrate having piezoelectricity
Data Source
AI summary
A reception filter includes a parallel arm resonator, a first longitudinally coupled resonance device including first acoustic wave resonators, and a second longitudinally coupled resonance device including second acoustic wave resonators, and cascade-connected to the first longitudinally coupled resonance device. Each of the first and second acoustic wave resonators include one end connected to a ground, the parallel arm resonator and the first and second longitudinally coupled resonance devices are provided on a piezoelectric substrate, and a ground to which the parallel arm resonator is connected, a ground to which at least one of the first acoustic wave resonators is connected, and a ground to which at least one of the second acoustic wave resonators is connected are commonly connected on the piezoelectric substrate.