基于介质谐振器和PCB技术的SPDT滤波开关

针对时分双工(time division duplex, TDD)子系统同时对滤波器和开关的需求，将二者相融合提出了一种滤波开关设计方案。介质谐振器滤波器因具有高Q值、低损耗等特点而被广泛研究，然而其不易与PIN管集成，难以实现开关功能。基于介质谐振器和印刷电路板(printed circuit board，PCB)技术设计了一种低损耗、高隔离度的单刀双掷(single pole double throw, SPDT)滤波开关。设计以介质谐振器滤波器为滤波主体，同时在PCB上实现SPDT开关功能，滤波功能和开关功能可独立设计，降低了设计难度。开关电路在导通状态时等效为一段传输线，因而仅会增加很少的插入损耗。加工并测试了一个设计实例，测试结果表明，打开状态下的带内损耗为0.92 dB左右，关闭状态下的隔离度优于47 dB。与传统单纯PCB滤波开关相比，该设计具有更低的插入损耗、更高的隔离度。

SPDT filtering switch based on dielectric resonators and PCB technology

According to the requirements of time division duplex (TDD) subsystems for both filter and switch, a filtering switch is designed by combining the filter and switch. Filters using dielectric resonators have been widely investigated due to its high-quality factor and low loss. However, it is not easy to integrate PIN diodes, and it is difficult to achieve switching function. In this paper, a single pole double throw (SPDT) filtering switch based on the dielectric resonator (DR) and the printed circuit board (PCB) technology is designed with low insertion loss and high isolation. In the design, the filtering function is realized by the DR part and the switching function is achieved on the PCB part. As a result, these two functions can be designed independently so that the design complexity can be reduced. When the switching circuit is on, it is equivalent to a transmission line. Therefore, it will only increase very small insertion loss. Finally, a design example is fabricated and measured for verification. The measured on-state insertion loss is around 0.92 dB, and the measured off-state isolation is better than 47 dB. As compared with the traditional filtering switches based only on PCB technology, the proposed design owns the advantages of lower insertion loss and higher isolation.