374～747MHz数字可调谐微带滤波器

374～747 MHz digital tunable microstrip filter

通过在微带开口谐振环加载数字可调电容,设计了一种新颖数字微带可调滤波器,同时提出了新型的非均匀开口谐振环混合耦合结构,使谐振器间耦合系数随谐振频率的降低而增大,实现恒定绝对带宽可调滤波器。接着对所提出的基于5 bit数字可调电容的数字可调微带滤波器进行了仿真和制作,测试表明,其通带中心频率可实现374~747 MHz可调,-3 d B绝对带宽在44~67 MHz之间变化,OIP3大于50 d Bm。

A novel digital microstrip tunable bandpass filter based on digitally tunable capacitor loading microstrip open ring resonators was proposed. The novel non-uniform open ring resonances with mixed coupling structure was used to make the coupling coefficient of the resonators increases with the decreasing of resonance frequency and achieve a constant absolute bandwidth tunable filter. Then the proposed digital tunable microstrip filters based on 5 bit digitally tunable capacitance was simulated and manufactured. The measurement shows that the -3 dB absolute bandwidth varies from 44-67 MHz while the central frequency of the passband varying from 374-747 MHz, the OIP3 is greater than 50 dBm.