一种具有可重构陷波功能的差分宽带带通滤波器

文章提出了一种具有陷波可重构功能的差分宽带带通滤波器,具有良好的差模响应与共模抑制效果。所设计的差分带通滤波器通过采用对称的四阶分支线结构,在差模激励下可等效出电壁,在共模激励下可等效出磁壁。同时,该滤波器通过对称地耦合两个1/4波长的阶梯阻抗谐振器来产生所需频段的陷波特性,并通过改变阶梯阻抗谐振器上变容二极管两端的直流偏置电压来改变阶梯阻抗谐振器的电长度,从而调整陷波的频段。仿真和测试结果表明该差分带通滤波器的工作频带为2.7~7.3 GHz,相对阻抗带宽为92%。在工作频段中,差模回波损耗均大于10 dB,共模抑制大于15 dB。随着变容二极管两端直流控制电压从10.3 V变化到3.6 V,陷波的中心频率从5.6 GHz移动到6.1 GHz,同时滤波器宽带带通特性基本保持不变。

A Reconfigurable Differential Wideband Bandpass Filter with One Notched Band

In recent years, balanced components have been utilized widely because of their high immunity to the environmental noise. A novel reconfigurable band-notched wideband differential bandpass filter is proposed in this paper, which obtains favorable differential-mode (DM) response and good common-mode (CM) suppression. With the adoption of the symmetric structure, the proposed filter presents a perfect electric conductor wall under differential-mode excitation and a perfect magnetic conductor wall under common mode excitation along the line of symmetry of the structure. By loading varactor diodes over the step-impedance reconators(SIRs), the effective electrical length of SIRs can be changed, leading to an electrically tunable notched band. The simulated and measured results show that a wide differential-mode passband is achieved in the frequency range of 2.7-7.3 GHz with a fractional bandwidth of about 92%. The DM return loss is better than 10 dB over the DM passband and the high CM suppression is greater than 15 dB. The center frequency of the notch-band can be tuned from 5.6 to 6.1 GHz by varying the bias voltage from 10.3 to 3.6V. Meanwhile, the broadband characteristics of bandpass filter is unchanged.