电磁寄生参数在高频SAW滤波器设计中的应用

在设计高频声表面波（SAW）滤波器的过程中，若只考虑封装壳和键合线的电磁寄生参数而忽略汇流条的电磁寄生参数，则SAW滤波器的实际性能易受汇流条寄生参数影响而出现通带波动和驻波增大等问题。该文拟用电声-电磁联合仿真方法设计高频SAW滤波器以解决汇流条寄生参数对SAW滤波器性能的影响。通过此方法研制的滤波器通带插入损耗小于1dB，波动0.5dB，通带内驻波最大值2.1，-1.5dB带宽75.7MHz，-3dB带宽84MHz(相对带宽为4.8%)，-30dB带宽112MHz，BW_{-3 dB}/BW_{-30 dB}矩形系数1.33。包含封装壳、键合线及汇流条的寄生参数的理论仿真结果与实验测试结果吻合较好，表明了采用此模型设计高频SAW滤波器的可行性。

Application of Parasitic Parameters to Design of High Frequency SAW Filter

In the process of designing high frequency surface acoustic wave (SAW) filters, if only the electromagnetic parasitic parameters of the package and the bonding line are considered and the electromagnetic parasitic parameters of the bus bar are ignored, the actual performance of SAW filters will be easily affected by the parasitic parameters of the bus bar, resulting in problems such as large passband ripple and large standing-wave ratio. In this paper, the co-simulation method of the electro-acoustic and electromagnetic is used to design high frequency SAW filter to solve the influence of the parasitic parameters of bus bar on the performance of SAW filter. Based on the proposed method, the filter with the passband insertion loss of less than 1 dB, passband ripple of 0.5 dB, passband standing wave of maximum 2.1,-1.5 dB bandwidth of 75.7 MHz,-3 dB bandwidth of 84 MHz (fractional bandwidth of 4.8%),-30 dB bandwidth of 112 MHz, and the BW_{-3 dB}/ BW_{-30 dB} rectangle factor of 1.33 is developed. The theoretical simulation results of parasitic parameters including the package, bonding wire and bus bar are in good agreement with the experimental test results, indicating the feasibility of using this model to design high-frequency SAW filters.