该文基于宽频枝节匹配方法提出了一种双通带薄膜体声波谐振器(FBAR)滤波器设计方法。基于S参数网络阻抗变换理论分析了滤波网络输入和输出端宽频匹配原理, 设计对应于两个不同频带FBAR滤波器的阻抗匹配枝节, 进而通过公共端的连接实现双通带FBAR滤波器的设计。匹配网络采用电容和电感可在基板上进行准确设计, 并通过在此基板上完成FBAR滤波器的装配实现双通带滤波器的整体集成。最终设计了一种中心频率分别为2 492 MHz和6 000 MHz的双通带滤波器。结果表明, 两个通带的插入损耗分别为3.29 dB和4.91 dB, 阻带抑制均小于-25 dB, 与理论设计结果匹配较好。

This paper proposed a dual-band film bulk acoustic resonator (FBAR) filter design method based on the wideband branch matching. Based on S-parameter network impedance transformation theory, the principle of broadband matching at the input and output terminals of the filter network is analyzed, and impedance matching branches corresponding to the two FBAR filter bands is designed. Then, the dual-band FBAR filter is constructed by connecting the common terminals of the two filtering networks. The capacitance and inductance of the matching network can be accurately designed on substrate, and the integration of the dual-band filter can be realized by mounting the two FBAR filters on the substrate. Finally, a dual-band filter with center frequencies of 2 492 MHz and 6 000 MHz is designed, fabricated and tested. The test results show that the insertion loss of the two bands are 3.29 dB and 4.91 dB respectively, and the stopband suppression is less than -25 dB, which is in good agreement with the theoretical ones.