基于LTCC的小型化中频带通滤波器设计

Design of Miniaturized IF Band Filter Based on LTCC

采用LTCC技术实现滤波器时,大电感值会引起加工复杂、寄生参数多等问题。文中通过部分电路等效法(PEEC)、三角形和星形联结等效变换法,将二阶直接耦合滤波器中的三角形连接电感等效为两个并联的耦合电感,减少了电感数量及感值。使得滤波器的设计复杂程度降低,标准化程度及一致性更高,封装更小。最终实现了一个中心频率70 MHz、相对带宽14.28%、插入损耗1.83 d B、回波损耗<-15 d B的小型化中频滤波器。

Large inductor value will cause multiple problems such as difficulties in manufacturing and complexity in parasitic parameters while implementing filters using LTCC technology. Due to partial-element equivalent-circuit model（ PEEC）,delta and star-connected circuit equivalent transformation,three inductors of the second order direct coupling filter can be replaced by two parallel coupling inductors,leading to lowering in the complexity of design,improving in standardization and consistency and smaller packing. Finally a small size intermediate frequency filter of 70 MHz center frequency,14. 28% relative bandwidth,1. 83 d B insertion loss and less than- 15 d B return loss is achieved.