DXBAR Diplexer Layout for Wideband 5G n77 and n79 Filtering
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Solution Overview
Problem
Existing RF filters using acoustic wave resonators are not well-suited for higher frequencies and wider bandwidths required in future communication networks, particularly for 5G NR bands n77 and n79.
Innovation Solution
The use of decoupled transversely-excited film bulk acoustic resonators (XBARs) with a decoupling dielectric layer between the IDT fingers and the piezoelectric diaphragm, allowing for tailored electromechanical coupling and improved frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional acoustic wave resonators are used, then existing filter designs can be maintained, but the filters are not suitable for higher frequencies and wider bandwidths required in 5G NR bands n77 and n79
Solution Approach 1:
The patent introduces a decoupling dielectric layer between the IDT fingers and the piezoelectric diaphragm, fundamentally changing the electromechanical coupling parameter. This allows independent optimization of resonance and anti-resonance frequencies, enabling the filter to achieve suitable frequency differences for 5G NR bands n77 (3300-4200 MHz) and n79 (4400-5000 MHz) while maintaining reliable filter performance
Solution Approach 2:
The decoupling dielectric layer acts as an intermediary element between the IDT fingers and the piezoelectric diaphragm. This intermediary structure enables tailored electromechanical coupling by controlling the interaction strength, thereby achieving the required frequency characteristics for higher frequency and wider bandwidth applications without sacrificing performance
2Adaptability or versatility
If a decoupling dielectric layer is added to enable tailored electromechanical coupling, then frequency characteristics are improved, but device complexity increases
Solution Approach 1:
The decoupling dielectric layer is applied locally at specific positions between the IDT fingers and the piezoelectric diaphragm, rather than uniformly throughout the entire structure. This localized approach enables tailored electromechanical coupling in critical regions while maintaining simplicity in other areas, thus improving frequency characteristics without proportionally increasing overall device complexity
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 enables the design of RF filters with suitable frequency differences for both band n77 and band n79, enhancing filter performance and compatibility with emerging communication standards.
Implementation Method 1
transversely-excited film bulk acoustic resonators (XBARs) with a decoupling dielectric layer between the IDT fingers and the piezoelectric diaphragm
Implementation Method 2
acoustic wave resonators including surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators, film bulk acoustic wave resonators (FBAR), and other types of acoustic resonators
Data Source
AI summary
Diplexers, filter devices, and methods are disclosed. A diplexer includes a first chip comprising series resonators of a high band filter, a second chip comprising shunt resonators of the high band filter and series resonators of a low band filters, and a third chip comprising shunt resonators of the low band filter. The series resonators and the shunt resonators of the high band filter are decoupled transversely-excited film bulk acoustic resonators (DXBARs). The series resonators and the shunt resonators of the low band filter are transversely-excited film bulk acoustic resonators (XBARs).