Acoustic Wave Multiplexer Shielding for Better Filter Isolation
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Solution Overview
Problem
In multiplexers with acoustic wave resonators, the isolation characteristic between filters deteriorates due to interference between resonators on a shared substrate, which affects the steepness of attenuation between passbands and guard bands.
Innovation Solution
Incorporating a metal structure on the substrate surface between acoustic wave resonators improves the isolation characteristic by reducing interference and enhancing the steepness of attenuation between passbands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If acoustic wave resonators are placed on a shared substrate to form filters, then the multiplexer can process multiple frequency bands, but the isolation characteristic between filters deteriorates due to interference between resonators
Solution Approach 1:
A metal structure is introduced as an intermediary element positioned between adjacent acoustic wave resonators on the substrate. This metal structure acts as a shield or barrier that blocks or reduces the electromagnetic interference between resonators, thereby improving isolation characteristics while allowing the resonators to remain on a shared substrate for multiplexer functionality.
Solution Approach 2:
The metal structure is selectively positioned only in the regions between adjacent resonators where interference occurs, rather than uniformly across the entire substrate. This localized approach maintains the necessary electromagnetic coupling for resonator operation while providing interference reduction precisely where needed between passbands.
2Area of stationary object
If acoustic wave resonators are placed close together on the substrate, then the device size is reduced, but the attenuation steepness between passbands decreases due to increased interference
Solution Approach 1:
The metal structure serves as a localized barrier between closely-spaced resonators, enabling them to be positioned nearer to each other while maintaining adequate attenuation steepness. The metal structure reduces the electromagnetic coupling between adjacent resonators, preventing interference that would otherwise degrade the attenuation characteristics between passbands.
3Device complexity
If no metal structure is added to the substrate, then the device complexity is low, but signal leakage occurs between adjacent passbands
Solution Approach 1:
A metal structure is introduced as an intermediary element positioned between adjacent acoustic wave resonators on the substrate. This metal structure acts as a shield or barrier that blocks or reduces the electromagnetic interference between resonators, thereby improving isolation characteristics while allowing the resonators to remain on a shared substrate for multiplexer functionality.
Solution Approach 2:
The metal structure is selectively positioned only in the regions between adjacent resonators where interference occurs, rather than uniformly across the entire substrate. This localized approach maintains the necessary electromagnetic coupling for resonator operation while providing interference reduction precisely where needed between passbands.
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 metal structure effectively improves the isolation between filters, maintaining the steepness of attenuation and reducing signal leakage across passbands, thereby enhancing the overall performance of the multiplexer.
Implementation Method 1
a metal structure that is located on the surface, and is located between the at least one first acoustic wave resonator and the at least one second acoustic wave resonator
Implementation Method 2
a first filter that is connected between the first terminal and the second terminal, includes a first capacitor, a first inductor, and one or more first acoustic wave resonators
Implementation Method 3
one or more first acoustic wave resonators and at least one second acoustic wave resonator of the one or more second acoustic wave resonators are located
Data Source
AI summary
A multiplexer includes: a first terminal; a second terminal; a third terminal; a first filter connected between the first and second terminals, including a first capacitor, a first inductor, and one or more first acoustic wave resonators, and having a first passband; a second filter connected between the first and third terminals, including a second capacitor, a second inductor, and one or more second acoustic wave resonators, and having a second passband higher than the first passband; a substrate having a surface on which at least one first acoustic wave resonator of the one or more first acoustic wave resonators and at least one second acoustic wave resonator of the one or more second acoustic wave resonators are located; and a metal structure located on the surface and located between the at least one first acoustic wave resonator and the at least one second acoustic wave resonator.