Acoustic Wave Multiplexer Using SAW Shunts for Low Harmonic Distortion
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Solution Overview
Problem
Acoustic wave filters, particularly in 5G New Radio applications, face challenges in achieving low second harmonic distortion and insertion loss, with existing BAW resonators experiencing spikes in frequency response due to lateral and recessed frame modes, while TCSAW resonators have higher insertion loss and degraded quality factor.
Innovation Solution
A multiplexer design incorporating a receive filter with a shunt surface acoustic wave (SAW) resonator and bulk acoustic wave (BAW) resonators, where the shunt SAW resonator has a resonant frequency within the transmit passband, reducing second harmonic distortion and achieving low insertion loss, and a transmit filter with BAW resonators and shunt SAW resonators for improved linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If bulk acoustic wave resonators are used, then insertion loss is reduced, but second harmonic distortion increases due to lateral and recessed frame mode spikes
Solution Approach 1:
The patent divides the filter into two distinct sections: a first section using BAW resonators for insertion loss performance and a second section using TCSAW resonators for second harmonic distortion suppression. This segmentation allows each resonator type to optimize for its strength without compromising the other.
Solution Approach 2:
Different resonator types are assigned to different locations within the filter structure based on their specific strengths. BAW resonators are placed where insertion loss is critical, while TCSAW resonators are placed where second harmonic distortion control is paramount, creating local optimization throughout the filter.
2Object-generated harmful factors
If temperature compensated surface acoustic wave resonators are used, then second harmonic distortion is reduced, but insertion loss increases and quality factor degrades
Solution Approach 1:
The patent divides the filter into two distinct sections: a first section using BAW resonators for insertion loss performance and a second section using TCSAW resonators for second harmonic distortion suppression. This segmentation allows each resonator type to optimize for its strength without compromising the other.
Solution Approach 2:
Different resonator types are assigned to different locations within the filter structure based on their specific strengths. BAW resonators are placed where insertion loss is critical, while TCSAW resonators are placed where second harmonic distortion control is paramount, creating local optimization throughout the filter.
3Device complexity
If a single type of resonator is used throughout the filter, then device complexity is reduced, but performance specifications cannot be met simultaneously
Solution Approach 1:
The patent divides the filter into two distinct sections: a first section using BAW resonators for insertion loss performance and a second section using TCSAW resonators for second harmonic distortion suppression. This segmentation allows each resonator type to optimize for its strength without compromising the other.
Solution Approach 2:
Different resonator types are assigned to different locations within the filter structure based on their specific strengths. BAW resonators are placed where insertion loss is critical, while TCSAW resonators are placed where second harmonic distortion control is paramount, creating local optimization throughout the filter.
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 design effectively reduces second harmonic distortion and maintains low insertion loss, enhancing system-level linearity in 5G New Radio applications by leveraging the better second harmonic performance of SAW resonators and the insertion loss characteristics of BAW resonators.
Implementation Method 1
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Implementation Method 2
In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer.
Implementation Method 3
An acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer
Data Source
AI summary
Aspects of this disclosure relate to multiplexers with acoustic wave resonators. The multiplexer includes a first filter and a second filter. The first filter includes a plurality of bulk acoustic wave resonators and a shunt surface acoustic wave resonator. The shunt acoustic wave resonator can have a resonant frequency in a passband of the second filter. The passband of the second filter is below a passband of the first filter. In certain applications, the first filter is a receive filter and the second filter is a transmit filter.