具有环形-圆形电极的薄膜体声波滤波器（英文）

Thin film bulk acoustic wave filters with ring-dot electrodes

目的:研发一种新型氧化锌薄膜体声波滤波器,建模进行理论分析,并给出设计工具。创新点:提出一种氧化锌薄膜体声波滤波器的新结构。方法:用Tiersten-Stevens方程进行理论分析与计算;方程及其求解和计算简单易行。结论:具有环形-圆形电极的氧化锌薄膜可以作为体声波滤波器。圆形和环形电极具有简单和易加工等优点,并且工作模态的振动分布与材料的对称性高度一致,避免了矩形电极角点引起的电场集中等缺点。该滤波器的最优工作状态需要通过精密设计实现,本文提供了理论和计算设计工具。

We propose a new structure of ZnO or A1N thin film bulk acoustic wave filters using a ring-dot driving electrode operating with thickness-extensional modes. A theoretical analysis is performed to show the operating frequencies and modes of the proposed filter. The scalar differential equation by Tiersten and Stevens （1983） is used. An analytical solution is obtained. Numerical calculations based on the solution show that the vibration tends to be trapped in the electroded central and annular areas and decays away from the electrode edges. It is also shown that by properly designing the electrode dimensions and mass density, the nodal line of one of the two operating modes can be adjusted to tie in the gap between the ring and the dot driving electrodes which is ideal for a filter.