Abstract: The modulation range of microstrip tunable filter’ central frequency is too narrow, to solve this problem, this paper designs a kind of tunable bandpass filter according to the theory of combline filter and the characteristic of variable capacitance diode. The simulation result of ADS proves that the modulation range of this tunable filter’ central frequency range from 0.49 GHz to 5.08 GHz, relative bandwidth is only 6.1%~9.4%. This combline tunable bandpass filter has many merits, such as the modulation range of its central frequency is very wide, the structure is simple, easy to be realizee, and convenient to be expanded. This tunable filter has definite application value in engineering field.

Key words: combline filter, tunable bandpass filter, variable capacitance diode, Advanced Design System（ADS）

摘要： 针对现有的微带可调滤波器中心频率调节范围较窄的问题，依据梳状滤波器的原理和变容二极管的特性，设计出一种梳状线可调带通滤波器，经ADS仿真可得其中心频率可调范围达到0.49～5.08 GHz、相对带宽仅为6.1％～9.4%，该梳状线可调带通滤波器具有中心频率调节范围很宽、结构简单、易于实现、易于扩展等优点，在工程上具有一定的推广应用价值。

关键词: 梳状滤波器, 可调带通滤波器, 变容二极管, 先进设计系统（ADS）