声表面波器件变频快速模拟方法*

声表面波器件的级联有限元模拟方法是从整体结构中分离出若干独立的基本单元,通过基本单元边界矩阵的级联实现有限长器件结构的模拟。在实际设计中,通过优化叉指换能器的指条周期,激发出不同波长的声表面波,调整声表面波器件的谐振频率,这导致级联有限元模拟方法存在频繁的单元建模与数据传输过程。为提高模拟效率,该文提出了一种波长(频率)变化时的级联有限元快速模拟方法。首先分析了不同波长对应单元系统矩阵间的关系,引入参考波长及波长变化因子,建立单元系统矩阵与波长之间的简易函数关系。接着利用参考波长的有限元模型快速计算出不同波长对应的单元系统矩阵,避免了多次单元建模与大量数据传输过程。最后利用边界矩阵的级联计算器件的频域响应,证明了该方法的有效性。

Fast simulation method for frequency change of surface acoustic wave devices

The hierarchical cascade technique for finite element method(HCT-FEM) separates several independent basic elements from surface acoustic wave device, and simulates finite length structure by cascading the boundary matrix of basic blocks. When designing SAW devices, the resonant frequency of the SAW device is adjusted by optimizing the period of interdigital transducer (IDT) and exciting SAW with different wavelength, which leads to frequent unit modeling and data transmission in HCT-FEM. In order to improve the efficiency of simulation, a HCT-FEM fast simulation method for wavelengths variation is presented. Firstly, the relationship between system matrix corresponding to different wavelength is analyzed. Introduce reference wavelength and wavelength change factor to establish a simple functional relationship between the unit system matrix and wavelength. Using FEM model with the reference wavelength, the unit system matrix corresponding to different wavelength can be calculated quickly, avoiding multiple unit modeling and large data transmission. Finally, the frequency domain response of the device is realized by cascading the boundary matrix, which proves the effectiveness of this method.