Signal-interference-based quasi-reflectionless bandpass filter for wideband and high-selectivity

This paper proposes a wideband quasi-reflectionless bandpass filter with high-selectivity based on signal-interference method. The bandpass filter is composed of a bandpass section and two absorptive sections, which consist of a quarter-wavelength coupled line and signal-interfering/resistively loaded path, respectively. The bandpass section mainly performs bandpass filtering characteristics while the absorptive sections are applied to consume the reflected signals. By virtue of rationally setting electric lengths and characteristic impedances of the absorptive section to form signal interference, signal dissipation within a wider frequency range and higher selectivity can be realized. Finally, the quasi-reflectionless bandpass filter was designed and demonstrated with well-matched measurement and simulation results. Compared with conventional works, the proposed bandpass filter can simultaneously attain wideband, high-selectivity, and two-port quasi-reflectionless performance within a single-layer topology and well-integrated structure owing to the signal-interference technology. The proposed technique may be extensively applied in the RF front-end and decreases the effect on the stability of communication systems caused by reflected signal. This paper proposes a wideband quasi-reflectionless bandpass filter with high-selectivity based on signal-interference method. The bandpass section mainly performs bandpass filtering characteristics while the absorptive sections are applied to consume the reflected signals. The resultant bandpass filter can attain enhanced bandwidth, quasi-reflectionless property, and high-selectivity with single-layer structure.image