Komatsu Tomoya, Tanaka Yasutomo, Hashimoto Ken-ya, Omori Tatsuya, Yamaguchi Masatsune
Graduate School of Engineering, Chiba University, Chiba, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Jul;56(7):1451-6. doi: 10.1109/TUFFC.2009.1200.
This paper proposes a new design technique for a ladder-type filter to reduce the passband width without sacrificing the insertion loss, out-of-band rejection, and steepness of the transition bands. First, it is shown that 2 transmission zeros can be generated by connecting an additional resonator in either series or parallel arm of the ladder filter topology. This new filter topology can be designed systematically by the derived-m transformation. Second, it is demonstrated that the narrow bandwidth, sharp transition bands, and large out-of- band rejection are simultaneously realized by applying the present technique to specifically designed ladder-type filters. Finally, this technique is applied to the design of a SAW filter fabricated on the Cu-grating/15 degrees YX-LiNbO3 structure.
本文提出了一种用于梯形滤波器的新设计技术，以在不牺牲插入损耗、带外抑制和过渡带陡度的情况下减小通带宽度。首先，研究表明，通过在梯形滤波器拓扑结构的串联或并联臂中连接一个额外的谐振器，可以产生2个传输零点。这种新的滤波器拓扑结构可以通过推导的m变换进行系统设计。其次，证明了通过将本技术应用于专门设计的梯形滤波器，可以同时实现窄带宽、尖锐的过渡带和大的带外抑制。最后，将该技术应用于在铜光栅/15度YX - 铌酸锂结构上制造的声表面波滤波器的设计。
