Phase-Cancelling SAW Circuit Layout for Acoustic 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 coupling between phase cancelling circuits and resonators, which deteriorate performance.
Innovation Solution
The device incorporates a phase cancelling circuit with a tapered sidewall and strategic positioning to prevent acoustic reflections, using a silicon oxide layer and offset acoustic tracks to reduce interference, and includes acoustic obstacles and angled electrical connections to suppress interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase cancelling circuit is integrated with the filter circuit in a multi-layer piezoelectric substrate SAW device, then signal isolation and interference suppression are improved, but acoustic wave reflections and coupling between circuits occur which deteriorate performance
Solution Approach 1:
The patent extracts the harmful acoustic reflections from the system by introducing acoustic obstacles (reflectors) that redirect these reflections away from the phase cancelling circuit. This separates the harmful acoustic energy from the sensitive circuit elements, thereby maintaining signal isolation while eliminating the deteriorating reflections.
Solution Approach 2:
The patent introduces acoustic obstacles as intermediary elements between the piezoelectric layer and the phase cancelling circuit. These obstacles act as mediators that intercept and redirect acoustic waves, preventing direct coupling between the filter circuit and phase cancelling circuit, thus improving isolation without causing additional reflections.
2Device complexity
If the phase cancelling circuit is positioned closer to the piezoelectric layer to reduce size, then device integration is improved, but acoustic coupling between the phase cancelling circuit and resonators increases which deteriorates performance
Solution Approach 1:
The patent positions acoustic obstacles between the phase cancelling circuit and the piezoelectric layer to serve as intermediaries. These obstacles block the acoustic coupling path while allowing the circuit to remain in close proximity to the piezoelectric layer for compact integration, thus resolving the contradiction between device size and acoustic isolation.
Solution Approach 2:
The patent applies local acoustic isolation measures by placing acoustic obstacles specifically in the regions where acoustic coupling occurs between the phase cancelling circuit and resonators. This localized approach maintains compact integration while suppressing harmful acoustic interactions in critical areas.
3Reliability
If acoustic obstacles are added to suppress reflections, then interference suppression is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the acoustic obstacles with existing device structures, such as integrating them into the substrate or combining them with other device components. This integration approach provides effective interference suppression while avoiding the need for separate manufacturing processes, thus maintaining ease of manufacture.
Solution Approach 2:
The patent designs acoustic obstacles that serve multiple functions: they suppress acoustic reflections, provide mechanical support, and may serve as electrical ground structures. This multi-functionality reduces the need for additional components and simplifies manufacturing while achieving effective interference suppression.
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 isolation and reduces interference, improving the performance and reliability of multi-layer piezoelectric substrate surface acoustic wave devices by minimizing signal leakage and reflections.
Implementation Method 1
surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters. 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
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
Data Source
AI summary
A multi-layer piezoelectric substrate surface acoustic wave device is disclosed. The surface 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, a phase cancelling circuit integrated with the filter circuit, and an acoustic obstruction structure in the acoustic track of the phase cancelling circuit. An acoustic track of the phase cancelling circuit is offset from the plurality of resonators.