该文设计了一种基于低温共烧陶瓷(LTCC）技术的小型化超宽带巴伦(Balun)滤波器。该巴伦滤波器由一个五阶带通滤波器和基于Marchand巴伦改进型巴伦级联组成, 带通滤波器采用耦合谐振式的设计方法, 设计成宽带高抑制巴伦滤波器, 在二阶、三阶和四阶谐振之间创新采用电感级联的拓扑结构, 使相对带宽在48%以上。巴伦输入与输出之间的耦合采用一种并联堆叠式耦合螺旋传输线, 增强了传输线之间的耦合, 并拓宽了巴伦的带宽。结果表明, 该巴伦滤波器通带为1.71~2.76 GHz, 插损均小于2.3 dB; 在50~669 MHz, 抑制大于35 dB; 在669~1 245 MHz, 抑制大于17 dB; 在3 205~3 400 MHz, 抑制大于27 dB; 在3 400~6 000 MHz, 抑制均大于30 dB。两个输出端口信号的相位差和幅度差分别为180°±15°(1 710~2 340 MHz)、180°±10°(2 500~2 760 MHz)和±1.0 dB, 具有较高的通用性和良好的应用市场。

This paper designs a miniaturized ultra-wideband Balun filter based on the low-temperature co-fired ceramic (LTCC) technology. The Balun filter consists of a fifth-order bandpass filter and a Marchand Barron-based modified Barron cascade. The bandpass filter is designed as a wideband high rejection Barron filter using a coupled resonant design method, and an innovative inductive cascade topology is used between the second, third and fourth order resonance, thus the relative bandwidth of 48% or even wider has been realized. The coupling between the Balun input and output uses a parallel stacked coupling spiral transmission line, which greatly enhances the coupling between transmission lines and widens the bandwidth of the Balun. The Balun filter passband is 1.71~2.76 GHz,and the insertion loss is less than 2.3 dB.At 50~669 MHz, the rejection is greater than 35 dB,at 669~1 245 MHz, the rejection is greater than 17 dB,at 3 205~3 400 MHz, the rejection is greater than 27 dB,and at 3 400~6 000 MHz, the rejection is greater than 30 dB. The phase difference and amplitude difference of the signals of the two output ports are 180°±15°(1 710~2 340 MHz), 180°±10°(2 500~2 760 MHz) and ±1.0 dB, respectively. The proposed filter has high versatility and good market application prospects.