Hybrid Acoustic Multiplexer Filter for Wideband Sharp Rejection
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Solution Overview
Problem
Existing filters struggle to effectively filter relatively high frequency radio frequency signals while meeting stringent filtering specifications, particularly in 5G wireless communications, due to challenges in achieving wide bandwidth and sharp rejections at frequencies close to the passband.
Innovation Solution
A cascaded filter design combining a hybrid acoustic LC filter with a non-acoustic LC filter, incorporating acoustic resonators, capacitors, and inductors, which includes a shunt resonator configuration to provide wide passbands and sharp rejections at frequencies close to the passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single filter type is used, then the device complexity is low, but the filtering performance at high frequencies with wide bandwidth and sharp rejection is insufficient
Solution Approach 1:
The patent combines two different filter types (acoustic wave filter and LC filter) into a single cascaded filter system. The acoustic wave filter provides sharp rejection at frequencies close to the passband, while the LC filter provides wide bandwidth and low insertion loss. This merging of different filtering technologies resolves the contradiction by achieving superior filtering performance without requiring an overly complex single-filter design.
Solution Approach 2:
The filtering function is segmented into two separate filter stages rather than using one monolithic filter. The first stage (acoustic wave filter) handles the sharp rejection requirement, while the second stage (LC filter) handles the wide bandwidth requirement. This segmentation allows each filter to be optimized for its specific function, improving overall performance while keeping individual filter complexities manageable.
2Reliability
If acoustic wave filters are used for high frequency filtering, then sharp rejection at frequencies close to passband is achieved, but the bandwidth is limited and insertion loss increases
Solution Approach 1:
The patent merges an acoustic wave filter (providing sharp rejection) with an LC filter (providing wide bandwidth) in a cascaded configuration. The LC filter stage follows the acoustic wave filter to compensate for the bandwidth limitations and insertion loss of the acoustic stage alone, thereby achieving both sharp rejection and wide bandwidth simultaneously.
Solution Approach 2:
The LC filter acts as an intermediary stage that follows the acoustic wave filter. It mediates between the sharp but narrow acoustic filtering and the requirement for wide bandwidth, providing the additional bandwidth and low-pass characteristics needed to achieve overall wide bandwidth performance while preserving the sharp rejection capability of the acoustic stage.
3Productivity
If LC filters are used for wide bandwidth, then the bandwidth is sufficient, but the rejection at frequencies close to passband becomes less sharp
Solution Approach 1:
The patent combines an LC filter (providing wide bandwidth) with an acoustic wave filter (providing sharp rejection) in a cascaded configuration. The acoustic wave filter stage precedes the LC filter stage, providing the sharp rejection at frequencies close to the passband, while the LC filter provides the wide bandwidth and low insertion loss characteristics.
Solution Approach 2:
The filtering function is segmented such that the acoustic wave filter handles the sharp rejection requirement at its designated frequency range, while the LC filter handles the wide bandwidth requirement. This functional segmentation allows each filter type to operate in its optimal performance regime, with the acoustic stage providing sharpness and the LC stage providing bandwidth.
4Device complexity
If high frequency filtering is implemented with single filter design, then the device simplicity is maintained, but the insertion loss becomes significant
Solution Approach 1:
The patent merges an acoustic wave filter with an LC filter in a cascaded configuration where the LC filter stage follows the acoustic wave filter stage. The LC filter provides low insertion loss characteristics that compensate for the losses in the acoustic wave filter, thereby reducing overall insertion loss while maintaining a relatively simple two-stage device structure.
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
The cascaded filter design achieves low-loss wide passbands and stringent out-of-band rejections, addressing the limitations of traditional filters by enhancing bandwidth and rejection capabilities, particularly in 5G carrier aggregation scenarios.
Implementation Method 1
An acoustic wave filter can include a plurality of acoustic resonators arranged to filter a radio frequency signal
Implementation Method 2
An LC filter includes at least an inductor and a capacitor. LC filters are non-acoustic filters that include passive components
Implementation Method 3
An LC filter includes at least an inductor and a capacitor
Data Source
AI summary
Aspects of this disclosure relate to a multiplexer with a hybrid acoustic passive filter. The multiplexer includes a plurality of filters configured to filter respective radio frequency signals, a shared filter coupled between each of the plurality of filters and a common node, and a radio frequency filter coupled to the common node. At least a first filter of the plurality of filters includes acoustic resonators and a non-acoustic passive component. Related multiplexers, wireless communication devices, and methods are disclosed.