关键词: 共模噪声吸收, 双频平衡滤波器, 共模噪声抑制, 高选择性, 电阻加载

Abstract: A high-selectivity dual-band balanced bandpass filter is proposed, which can achieve wideband common-mode noise suppression and absorption. Two operational frequencies can be adjusted by the impedances of coupled-lines. Transmission zeros and bandwidths can be controlled by changing the electrical lengths of coupled-lines and loaded stubs. The filter can realize the wideband common-mode noise absorption and suppression by loading four grounded resistors. A dual-band balanced bandpass filter centered at 710 MHz and 2.37 GHz is fabricated for demonstration. The measured results indicate that the balanced bandpass filter has good differential-mode filtering performance with multiple transmission zeros. The common-mode suppression is better than 28 dB from 0 to 4.04 GHz. The common-mode noise absorption is better than 10 dB from 0 to 3.67 GHz, and the absorption rate of common-mode noise is greater than 90% from 0 to 4.37 GHz, which indicates significant improvements in term of common-mode noise elimination.