Acoustic Wave Device Ground Pattern Isolation
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Solution Overview
Problem
The isolation characteristic of acoustic wave filters in existing acoustic wave devices deteriorates due to interference between filters formed on different surfaces, leading to capacitive coupling and signal leakage.
Innovation Solution
Incorporating a ground pattern on the substrate between the transmit filter and receive pad, electrically separated from the filters, to inhibit capacitive coupling and improve isolation by ensuring the receive filter at least partially overlaps with the transmit filter in plan view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If acoustic wave filters are formed on different surfaces and stacked to downsize the device, then the device size is reduced, but the isolation characteristic deteriorates due to interference between filters
Solution Approach 1:
A ground pattern is introduced as an intermediary element between the transmit filter and receive pad on the first surface. This ground pattern acts as a mediator to control and reduce capacitive coupling, thereby improving isolation characteristics while maintaining the stacked configuration that achieves device downsizing.
Solution Approach 2:
The ground pattern is strategically positioned in specific locations between the transmit filter and receive pad, creating localized electromagnetic field control. This local modification of the electromagnetic environment reduces interference in the critical coupling region without affecting the overall stacked structure that enables compact size.
2Volume of moving object
If acoustic wave filters are stacked on different surfaces, then device size is reduced, but capacitive coupling causes signal leakage
Solution Approach 1:
The ground pattern serves as an intermediary structure that controls the electromagnetic field distribution between the transmit filter and receive pad. By introducing this intermediate element, the harmful capacitive coupling and resulting signal leakage are suppressed while the stacked compact configuration is maintained.
Solution Approach 2:
The ground pattern converts the potentially harmful capacitive coupling effect into a beneficial isolation mechanism. By strategically placing the ground pattern, the electromagnetic field distribution is controlled to reduce signal leakage, transforming what would be a harmful coupling effect into a useful isolation feature.
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 ground pattern effectively separates the transmit filter and receive pad, enhancing the isolation characteristic by reducing capacitive coupling and preventing signal leakage, thereby improving the device's filtering performance.
Implementation Method 1
the acoustic wave filters interfere with each other, and thereby, the isolation characteristic deteriorates
Data Source
AI summary
An acoustic wave device includes: a first substrate; a first acoustic wave filter located on a first surface of the first substrate; a pad that is located on the first surface and electrically separated from the first acoustic wave filter in the first surface; a ground pattern that is located on the first surface, and is located between the pad and the first acoustic wave filter in the first surface; and a second acoustic wave filter that is electrically connected to the pad, and at least partially overlaps with the first acoustic wave filter in plan view.