中文摘要：

通过在AlN薄膜体声波谐振器上引入压电缓冲层和外部电阻抗来调节谐振器的频率特性，在考虑了缓冲层和外部电阻抗后，得到薄膜谐振器的输入电阻抗公式，并用来描述器件的机电行为。通过计算阻抗一频率谱评估了薄膜谐振器的频率特性和有效机电耦合系数keff^2，研究了缓冲层和外部电阻抗包括电阻、电感、电容对薄膜谐振器的阻抗一频率谱的影响。计算结果表明，外部电阻抗的引入可根本上改变薄膜谐振器的共振频率，且对keff^2有重要的影响。

英文摘要：

For an A1N thin film bulk acoustic resonator （FBAR）, a passive piezoelectric layer and external electrical impedance are introduced into the thin film resonator structure for tuning the frequency characteristics of the resonator. The input electric impedance formula for the thin film resonator, after taking into account the passive piezoelectric layer and external impedance, is derived to describe the electromechanical behavior of the device. The frequency characteristics and effective electromechanical coupling coefficient k~ff of the thin film resonator are evalua- ted based on the calculated impedance-frequency spectra. The effect of the external electric impedance, including electric resistance, inductance and capacitance, on the impedance-frequency spectra of thin film resonator is investi- gated, and the calculation results reveal that the use of external electric impedance can substantially change the reso- nance frequency and has a significant effect on k~fr of the resonator.