Phase-Cancelling SAW Filter Layout for Reflection Isolation
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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 couplings within phase cancelling circuits, which degrade the performance of the filters.
Innovation Solution
The integration of a phase cancelling circuit with a tapered sidewall structure and strategic positioning to offset the acoustic track from resonators, combined with interference suppression structures, reduces unwanted reflections and couplings.
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 isolation is improved, but acoustic wave reflections and couplings within the phase cancelling circuit cause interference that degrades performance
Solution Approach 1:
The patent extracts and removes the harmful acoustic wave reflections and couplings from the phase cancelling circuit by carefully designing the acoustic track layout to avoid resonators and position the circuit away from piezoelectric layer edges, thereby eliminating the interference sources while preserving the phase cancellation function
Solution Approach 2:
The patent introduces an acoustic track as an intermediary pathway that guides acoustic waves from the phase cancelling circuit electrodes through a defined route to the output, ensuring that the acoustic waves do not couple with resonators or reflect harmful waves back into the circuit
2Area of stationary object
If the phase cancelling circuit is positioned close to the piezoelectric layer edges to maximize space utilization, then device area is reduced, but acoustic wave reflections from the edges increase interference
Solution Approach 1:
The patent applies local quality by creating a specialized acoustic track environment with specific properties (bounded by sidewalls, positioned at controlled distances from edges) that differ from the general device area, allowing the phase cancelling circuit to operate without harmful reflections while maintaining space efficiency
3Device complexity
If the acoustic track of the phase cancelling circuit overlaps with resonators, then device complexity is reduced, but acoustic wave couplings cause interference and performance degradation
Solution Approach 1:
The patent segments the device into distinct functional zones: a phase cancelling circuit zone with its dedicated acoustic track, and a resonator zone. This spatial segmentation prevents acoustic wave coupling between the phase cancelling circuit and resonators while maintaining overall device integration
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
Enhances filter isolation and performance by minimizing interference, achieving high isolation and reduced signal leakage in multi-layer piezoelectric substrate surface acoustic wave devices.
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 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 extends between a first periphery portion and a second periphery portion of the sidewall. The phase cancelling circuit is positioned within center seventy percent of a width between the first periphery portion and the second periphery portion.