BAW-SAW Filter Circuit for Second Harmonic Suppression
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Solution Overview
Problem
Existing bulk acoustic wave (BAW) devices, such as duplexers, face challenges in effectively suppressing harmonics generated during signal filtering, which can interfere with circuit operations.
Innovation Solution
The implementation of a filter circuit that combines bulk acoustic wave (BAW) resonators for signal filtering with surface acoustic wave (SAW) resonators to suppress harmonics, specifically configuring the SAW resonators as a notch filter to target second harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BAW resonators are used for signal filtering, then filtering performance is improved, but harmonic interference increases
Solution Approach 1:
The patent combines BAW resonators for signal filtering with SAW resonators for harmonic suppression into a single integrated filter circuit. The BAW resonators provide the primary band-pass filtering function, while the SAW resonators are configured to specifically suppress harmonic frequencies generated by the BAW resonators, thereby resolving the contradiction between improved filtering performance and reduced harmonic interference
Solution Approach 2:
The SAW resonators act as an intermediary element between the BAW resonators and the output. They receive the filtered signal from the BAW resonators and selectively remove harmonic components before the signal is output, thus mediating the harmful effect of harmonics generated by the BAW resonators
2Object-generated harmful factors
If SAW resonators are added to suppress harmonics, then harmonic interference is reduced, but device complexity increases
Solution Approach 1:
The filter circuit is segmented into distinct functional assemblies: a first assembly containing BAW resonators for signal filtering and a second assembly containing SAW resonators for harmonic suppression. This segmentation allows each assembly to be optimized for its specific function while maintaining overall system manageability and reducing design complexity through modular functional division
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 combination effectively reduces harmonic interference, enhancing the filtering performance and operational stability of BAW devices like duplexers.
Implementation Method 1
Each BAW resonator can include a piezoelectric material layer implemented between a lower electrode and an upper electrode
Implementation Method 2
Each SAW resonator can include a piezoelectric material layer implemented over the substrate
Data Source
AI summary
A radio-frequency module can include a filter circuit having an input node and an output node. The filter circuit can further include a first assembly having one or more bulk acoustic wave resonators implemented electrically between the input node and the output node, and configured to filter a signal. The filter circuit can further include a second assembly having one or more surface acoustic wave resonators implemented electrically relative to the first assembly, and configured to suppress one or more harmonics resulting from the filtering of the signal by the first assembly.