加厚膜片带通滤波器的仿真设计

Simulation design for band-pass filter with thick-film

随着频率应用的提高,传统的电感膜片耦合波导式带通滤波器已经不能适应机加工的现有能力和精度要求。通过增加膜片的厚度可以降低对机加工能力的要求,同时也易于满足设计精度的要求。本文通过CAD仿真设计,由传统的薄电感膜片带通滤波器设计原理演绎出加厚膜片带通滤波器的设计原理,并且通过对单节电感膜片和多级电感膜片级连滤波器电路特性的分析,得出了它们在滤波器中级联时对电性能贡献的共性。本文采用高频电磁场仿真进行计算,优化具体的电尺寸,给出了具体的设计实例。实测的结果和理论设计仿真的结果一致性较高。这种加厚膜片的滤波器能够扩展到毫米波频段应用,而且易于加工;运用S参数的等效性和高频电磁场仿真软件可以方便、准确地设计出易于加工、性能良好的滤波器件。这种设计方法同样适用于其他微波器件的设计(如电感销钉滤波器等)。

With the increasing applications of high-frequency band-pass filters, the conventional inductive thick-film band pass filter cannot meet the current manufacturing capability and accuracy requirements. By making the film thicker and maintaining the equivalent electrical characteristics, the requirements on accuracy and manufacturing capability can be easily met. This paper describes the design principle of thick-film band-pass filter derived from the conventional inductive thin-film band-pass filter design by CAD simulations. The electric characteristics of single-node inductance film and multistage inductance film cascade filter have been compared and analyzed. Their common contributions to the electrical characteristics of the filter have been verified. The HFSS （high frequency simulation system） is used as a tool for design, simulation and optimization, and the design example is also demonstrated. The measured results are in consistent with the simulation results very well. This filter design makes manufacture easier and improves the performance of products. The design principle introduced in this paper also can be applied into millimeter wave applications and used for other microwave components.