压电换能器电调七阶微带滤波器的设计

Design of Piezoelectric Transducer Electrically-Tuned Seven-Order Microstrip Filter

为了解决电容管电调滤波器插入损耗大的问题,该文设计了一款以压电换能器为电调元件、介质基片为微扰片的七阶平行耦合线电调滤波器。采用高频结构仿真器(HFSS)和先进的设计系统(ADS)对滤波器的结构参数进行联合仿真和优化,分析了滤波器的耦合系数和外部品质因数随微扰片间距变化的关系。将氧化铝陶瓷基板、压电换能器(PET)和微带滤波器组装在一起构成压电换能器电调滤波器,并用网络分析仪测量滤波器在不同直流电压下的S参数。测量结果表明,中心频率调谐范围为4.38~4.78 GHz时,通带的反射损耗大于10 dB,插入损耗小于1.5 dB,达到了设计要求。

In order to solve the problem of high insertion loss of varactor tuned filters,a piezoelectric transducer(PET)electrically tuned seven-order parallel-coupled line filter is designed with a piezoelectric transducer as a tuning element and a dielectric substrate as a perturber.The high frequency structure simulator(HFSS)and the advanced design system(ADS)were used to co-simulate and optimize the structure parameters of the proposed filter.The relationship between the coupling coefficient and external quality factor of the filter with the change of the gap between the perturber and the microstrip lines is analyzed.A piece of alumina ceramic substrate,a PET and the microstrip filter were assembled together to construct a PET electrically tuned filter,and the S parameter of the proposed filter are measured with a network analyzer under different dc voltages.The measurement results show that the tuned range of the center frequency is from 4.38 GHz to 4.78 GHz,the reflection loss of the passband in the tuned range is greater than 10 dB,and the insertion loss is less than 1.5 dB,which meets the design requirements.