基于正交相位的吸收式带通滤波组件设计

The design of a kind of reflectionless band-pass filtering module based on quadrature phase

提出了一种吸收式带通滤波器组件,由等相位功率分配-合成器、"+45°"高通滤波移相器、"-45°"低通滤波移相器和广义切比雪夫滤波器组-合成器对两支路正交信号进行合成;实现了对其相位和幅度的抵消,从而有效地吸收了带外返回信号,减小了带外信号反射量。基于该结构,设计实现了一款中心频率70MHz、IL≤4dB、BW_(-3dB)≤4.5MHz及BW_(ab)(吸收带宽):BW_(-3dB)≥10的吸收式带通滤波组件。

In this paper we propose a kind of reflectionless band-pass filtering module consisting of two 0 degree two-way combiner-splitters, two “＋45°” high-pass filtering phase shifters, two “-45°” low-pass filtering phase shifters and two general Chebychev filters. The “＋45°”and“-45°”phase shifters are used to shift the two branches reflect signals “＋90°” and “-90°” separately. When the reflect signals were transmited to the port of combiner-splitters, their phase and amplitude would be mutually offset. Therefore the module could reduce the power of out-of-band reflecting signals effectively. Based on this structure, a reflectionless band-pass filtering module was designed with center frequency of 70MHz, IL≤4dB, BW-3dB≤4.5MHz, BWab （the reflectionless bandwidth） ： BW-3dB≥10