Cascaded Hybrid Acoustic LC Filter for RF Harmonic Rejection
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Solution Overview
Problem
Current filters face challenges in effectively filtering high-frequency radio frequency signals while meeting stringent performance specifications, particularly in achieving wide bandwidth and sharp rejections at frequencies close to the passband without significant loss.
Innovation Solution
A cascaded filter configuration combining a hybrid acoustic LC filter with a non-acoustic LC filter, where the hybrid acoustic LC filter includes acoustic resonators, capacitors, and inductors, and the non-acoustic LC filter includes integrated passive devices, providing a wide passband and sharp rejections by leveraging the high quality factor of acoustic resonators and the low-loss characteristics of LC circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an acoustic wave filter is used to filter high frequency radio frequency signals, then the filtering capability at high frequencies is improved, but the bandwidth becomes limited and insertion loss increases
Solution Approach 1:
The patent combines acoustic wave filters with LC filters in a hybrid configuration. The acoustic wave filter provides sharp rejection at specific frequencies, while the LC filter contributes wide bandwidth and low insertion loss characteristics. This merging of two different filtering technologies allows the system to simultaneously achieve high-frequency filtering capability, wide bandwidth, and low loss that neither filter type could provide alone.
2Productivity
If an LC filter is used to achieve wide bandwidth, then the bandwidth is improved, but the rejection at frequencies close to the passband becomes insufficient
Solution Approach 1:
The hybrid filter configuration merges LC filter sections with acoustic wave filter sections. The LC filter portions provide wide bandwidth and low insertion loss, while the acoustic wave filter portions deliver sharp rejection at frequencies adjacent to the passband. This combination allows the system to overcome the individual limitations of each filter type.
3Measurement precision
If a purely acoustic wave filter is used, then sharp rejection is achieved, but the insertion loss becomes significant
Solution Approach 1:
The patent creates a hybrid architecture where acoustic wave filters and LC filters work together. The acoustic wave filters provide the necessary sharp rejection characteristics, while the LC filter sections contribute low insertion loss properties. This merging allows the system to achieve both sharp rejection and low energy loss simultaneously.
4Loss of energy
If a purely non-acoustic LC filter is used, then low loss is achieved, but the filtering performance at high frequencies becomes insufficient
Solution Approach 1:
The hybrid filter design merges LC filter elements with acoustic wave filter elements. The LC filter portions maintain low insertion loss characteristics, while the acoustic wave filter portions provide superior high-frequency filtering performance with sharp rejection. This combination enables the system to achieve both low loss and high filtering performance at high frequencies.
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 a wide passband with low insertion loss and strong suppression of intermodulation frequencies and harmonics, meeting stringent carrier aggregation specifications for 5G wireless communications.
Implementation Method 1
An acoustic wave filter can include a plurality of acoustic resonators arranged to filter a radio frequency signal
Implementation Method 2
LC filters are non-acoustic filters that include passive components
Implementation Method 3
LC filters are non-acoustic filters that include passive components
Data Source
AI summary
Aspects of this disclosure relate to hybrid acoustic LC filter with harmonic suppression. The hybrid acoustic LC filter includes a hybrid passive/acoustic and a non-acoustic LC filter cascaded with the hybrid passive/acoustic filter. The hybrid passive/acoustic filter can be configured to filter a radio frequency signal. The hybrid passive/acoustic filter can include acoustic resonators and a non-acoustic passive component. The non-acoustic LC filter can be configured to suppress a harmonic of the radio frequency signal. The non-acoustic LC filter can be a low pass filter or a harmonic notch filter, for example. Related multiplexers, wireless communication devices, and methods are disclosed.