The invention discloses a differential dual-
frequency band-pass filter with
high selectivity. By the differential dual-
frequency band-pass filter with
high selectivity, the problem of poor out-of-bandselectivity in design of the differential dual-
frequency band-pass filter is solved. A first uniform impedance resonant ring, a second uniform impedance resonant ring, an input
microstrip line and anoutput
microstrip line are arranged on an upper surface of a
dielectric substrate, the first uniform impedance resonant ring and the second uniform impedance resonant ring are embedded to each other,the input
microstrip line and the output microstrip line are symmetric to each other, and a step impedance gap line comprising a central loading
branch is arranged on a lower surface. L-shaped open-circuit branches are loaded on the input / output microstrip lines, the central loading
branch of the gap line passes through a
projection line of a center of the dual-frequency band-pass filter and is arranged at the center of a T-shaped gap line, and the dual-frequency band-pass
resonator is of a folded and embedded structure. By adding a transmission zero point mode, the
frequency selectivity is improved, the space
utilization rate and the integration are effectively improved, the design complexity is reduced, and the differential dual-frequency band-pass filter has the advantages of small introduction
noise, high interference-resistant capability and small loss and is widely applied to a
mobile wireless communication
system.