Bulk Acoustic Resonator Filter Layout for Wider Pass Bandwidth
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Solution Overview
Problem
Existing bulk acoustic resonator filters face challenges in achieving a wide pass bandwidth and reducing antiresonant frequency differences between shunt acoustic resonators, leading to potential splitting of bandwidths and increased insertion and return losses.
Innovation Solution
The design incorporates shunt acoustic resonators with varying aspect ratios and connection configurations, including series and parallel connections, to minimize antiresonant frequency differences and optimize resonant frequency alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If shunt acoustic resonators have uniform dimensions, then manufacturing is simplified, but antiresonant frequency differences increase causing bandwidth splitting
Solution Approach 1:
The patent applies local quality by making each shunt acoustic resonator have different dimensions (specifically different lengths) tailored to its position in the filter. This allows each resonator to be optimized for its local electrical environment, achieving precise antiresonant frequency alignment across all resonators while maintaining manufacturing simplicity through a systematic design approach.
Solution Approach 2:
The patent changes the physical parameters (lengths) of the shunt acoustic resonators to compensate for electrical parameter variations. By adjusting the length parameter of each resonator based on its position and connection configuration, the design achieves uniform antiresonant frequencies despite differences in electrical environments, thereby preventing bandwidth splitting.
2Reliability
If shunt acoustic resonators are connected with long connection lengths, then electrical connectivity is improved, but antiresonant frequency differences increase
Solution Approach 1:
The patent compensates for the adverse effect of long connection lengths by adjusting the length parameter of shunt acoustic resonators. Resonators with longer connection lengths are made shorter in physical dimension to offset the additional electrical path length, thereby maintaining uniform antiresonant frequencies while ensuring reliable electrical connectivity.
3Stability of the object's composition
If all acoustic resonators have the same aspect ratio, then design consistency is maintained, but pass bandwidth is limited
Solution Approach 1:
The patent applies local quality by assigning different aspect ratios to different acoustic resonators based on their specific functions and positions in the filter. Series acoustic resonators have one aspect ratio optimized for pass bandwidth, while shunt acoustic resonators have different aspect ratios optimized for stop bandwidth and antiresonant frequency alignment, achieving both design consistency and enhanced performance.
4Manufacturing precision
If shunt acoustic resonators have high aspect ratios, then resonant frequency is improved, but device area increases
Solution Approach 1:
The patent optimizes the aspect ratio parameter of shunt acoustic resonators to achieve the desired resonant frequency while minimizing device area. By carefully selecting aspect ratios within a specific range and adjusting resonator lengths, the design achieves precise frequency control without excessive area consumption.
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 approach enhances the pass bandwidth and reduces insertion and return losses, ensuring a stable and efficient frequency response with reduced heat generation and damage risk.
Implementation Method 1
each of the plurality of shunt acoustic resonators includes a resonance portion including a first electrode, a piezoelectric layer, and a second electrode stacked in a first direction
Data Source
AI summary
A bulk acoustic resonator filter includes a series part including at least one series acoustic resonator electrically connected between a first and second radio frequency ports; and shunt acoustic resonators electrically connected to each other in series between a first node of the series part and a first ground port, wherein each of the shunt acoustic resonators comprises a resonance portion including a first electrode, a piezoelectric layer, and a second electrode; and an overlap region in which the first electrode, the piezoelectric layer, and the second electrode overlap, the overlap region has an aspect ratio equal to a ratio between a longest length of the overlap region in an extension direction of a longest side of the overlap region and a longest length of the overlap region in a direction perpendicular to the extension direction, and the aspect ratios of the shunt acoustic resonators include different aspect ratios.