高频低温漂TC-SAW滤波器的设计

Design of TC-SAW Filter with High Frequency and Low Temperature Drift

该文设计了一款温度补偿型声表面波(TC-SAW)滤波器,建立了弹性材料及压电材料温度方程,对滤波器的温度场进行仿真分析。通过在压电材料(128°YX-LiNbO3)上沉积SiO2作为温度补偿层,降低了滤波器的频率温度系数。为了解决在沉积SiO2温度补偿层后,谐振器的反谐振频率处出现杂散响应,通过增加电极厚度,降低了谐振器杂散响应对滤波器性能的影响。采用四阶级联提高滤波器的带外抑制。仿真结果表明,设计的TC-SAW滤波器中心频率为2497 MHz,频率温度系数为-9.89×10^(-6)/℃,-30~85℃工作温度范围内的带内最大插损为1.95 dB,带外抑制大于30 dB,-3 dB损耗带宽大于97 MHz。

A temperature compensated surface acoustic wave(TC-SAW)filter was designed.The temperature equations of elastic materials and piezoelectric materials were established,and the temperature field of the filter was simulated and analyzed.The temperature coefficient of frequency(TCF)of the filter was reduced by depositing SiO 2 temperature compensated layer on the piezoelectric material(128°YX-LiNbO 3).In order to eliminate the spurious response at the anti-resonant frequency of the resonator after adding the SiO 2,the influence of the spurious response on the filter performance was reduced by increasing the electrode thickness.The fourth-order cascade was used to increase the out-of-band rejection of the filter.The simulation results show that the designed TC-SAW filter has a center frequency of 2497 MHz,temperature coefficient of frequency(TCF)of-9.89×10^(-6)/℃,maximum in-band insertion loss of 1.95 dB at the temperature range from-30℃to 85℃,out-of-band rejection of greater than 30 dB,and-3 dB bandwidth of greater than 97 MHz.