Multi-Die Acoustic Wave Multiplexer for Transmission Line Impedance Matching
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Solution Overview
Problem
Existing acoustic wave filters in multiplexers face challenges in maintaining low insertion loss and high reflection coefficients due to impedance mismatches caused by transmission lines between acoustic resonators and common nodes, which can lead to degraded performance and increased module size and cost when using phase rotation circuits.
Innovation Solution
The implementation of a multiplexer design with acoustic wave filters on multiple dies, where acoustic resonators on one die are electrically connected to a common node via a transmission line, and additional resonators on another die provide high impedance at specific passbands, reducing the effects of transmission lines and allowing for improved impedance matching without the need for phase rotation circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If acoustic wave filters are implemented by a plurality of die in multiplexers, then device integration is improved, but insertion loss increases and reflection coefficient decreases due to impedance mismatches caused by transmission lines
Solution Approach 1:
A switch is introduced as an intermediary component between the acoustic resonators on different dies and the common node. The switch enables selective connection of resonators to the common node based on the desired passband, acting as a mediator that prevents unwanted impedance interactions between dies while maintaining proper impedance matching for the active filter path.
Solution Approach 2:
The patent employs dynamically controllable switches to change the connectivity configuration between dies and the common node depending on the operating frequency band. This dynamic reconfiguration allows the system to optimize impedance matching for each specific passband, preventing the degradation caused by fixed multi-die configurations.
2Adaptability or versatility
If acoustic wave filters are implemented by a plurality of die in multiplexers, then device integration is improved, but reflection coefficient decreases due to impedance mismatches
Solution Approach 1:
The switch serves as a mediator that isolates the common node from impedance mismatches introduced by multiple dies. By selectively connecting only the necessary resonators to the common node for each passband, the switch prevents reflection coefficient degradation while preserving the benefits of multi-die integration.
Solution Approach 2:
Dynamic switching enables the system to adapt its impedance characteristics to match the requirements of each specific passband. This dynamic adjustment maintains high reflection coefficients by ensuring proper impedance matching only for the active filter path, while other dies remain isolated and do not contribute to impedance mismatches.
3Reliability
If phase rotation circuits are added to correct impedance mismatches, then impedance matching is improved, but device complexity and module size increase
Solution Approach 1:
The patent replaces the traditional mechanical/passive phase rotation circuit approach with an electronically controlled switching mechanism. This substitution achieves impedance matching through dynamic connectivity control rather than physical phase adjustment circuits, thereby reducing module size and complexity while maintaining or improving impedance matching performance.
Solution Approach 2:
Instead of using static phase rotation circuits that add complexity, the patent employs dynamic switching to achieve impedance matching. The switches enable the system to adapt its configuration in real-time, providing the necessary impedance correction without the bulk and complexity of dedicated phase rotation hardware.
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 design achieves lower insertion loss and reduced module size while maintaining high reflection coefficients, suitable for wide bandwidths and sharp passbands, addressing the technical challenges of carrier aggregation in 5G and 4G LTE bands.
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
The first acoustic resonator is electrically connected to the second acoustic resonator via a transmission line.
Data Source
AI summary
Aspects of this disclosure relate to a multiplexer that includes an acoustic wave filter including acoustic wave resonators on at least two die with a transmission line electrically connecting the acoustic wave resonators on the two die. The acoustic wave filter can include a plurality of acoustic wave resonators on a first die electrically connected to at least one acoustic wave resonator on a second die via the transmission line. The acoustic wave resonator on the second die can provide a relatively high impedance at a respective passband of one or more other filters of the multiplexer. This can reduce effects of the transmission line of the acoustic wave filter on a respective passband of one or more other filters of the multiplexer.