MPS-SAW Filter Layout With Offset Phase-Canceling Acoustic Track
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Solution Overview
Problem
Existing multi-layer piezoelectric substrate surface acoustic wave devices face interference issues due to acoustic wave reflections and coupling between phase cancelling circuits and resonators, which degrade the performance of the filter.
Innovation Solution
The device incorporates a phase cancelling circuit with a tapered sidewall design and strategic positioning to offset the acoustic track from resonators, along with interference suppression structures like angled electrical connections and acoustic obstacles, to minimize reflections and coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase cancelling circuit is integrated with the filter circuit in an MPS-SAW device, then signal leakage is reduced and filter performance is improved, but acoustic wave reflections and coupling between the phase cancelling circuit and resonators cause interference that degrades performance
Solution Approach 1:
The patent extracts and removes the harmful acoustic wave reflections and coupling interference from the system by carefully designing the acoustic track layout to avoid interaction between the phase cancelling circuit and resonators, thereby eliminating the interference while preserving the phase cancellation function
Solution Approach 2:
The patent introduces an acoustic track as an intermediary pathway that directs acoustic waves from the phase cancelling circuit to the output without allowing them to couple with the resonators, thus mediating between the phase cancelling circuit and the rest of the filter while preventing harmful interactions
2Area of stationary object
If the phase cancelling circuit is positioned closer to the piezoelectric layer edges, then the device footprint is reduced, but acoustic wave reflections from the edges increase causing more interference
Solution Approach 1:
The patent applies local quality by creating a specific acoustic track region with controlled properties that guides acoustic waves away from the piezoelectric layer edges, thereby maintaining compact positioning while preventing edge reflections through localized acoustic path management
Solution Approach 2:
The patent resolves the contradiction by transitioning from a two-dimensional placement problem to a three-dimensional acoustic path design, where the acoustic track is positioned at a specific depth and angle within the piezoelectric layer to avoid edge reflections while maintaining compact overall device dimensions
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 enhances the isolation and reduces interference in the phase cancelling circuit, resulting in improved filter performance with reduced signal leakage and increased reliability.
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
Implementation Method 2
a phase cancelling circuit integrated with the filter circuit, an acoustic track of the phase cancelling circuit extending between a first periphery portion and a second periphery portion of the sidewall
Data Source
AI summary
A multi-layer piezoelectric substrate surface acoustic wave device is disclosed. The acoustic wave device can include a multi-layer piezoelectric substrate including a support substrate and a piezoelectric layer, a filter circuit including a plurality of resonators in electrical communication with the piezoelectric layer and a phase cancelling circuit integrated with the filter circuit. The piezoelectric layer has a first side facing the support substrate, a second side opposite the first side, and a sidewall extending between the first side and the second side and defining a periphery of the piezoelectric layer. The sidewall is tapered such that the first side is wider than the second side. An acoustic track of the phase cancelling circuit is offset from the plurality of resonators.