Multi-transmission zero balancing filter using coupling feeder lines to perform loading

Abstract

The invention discloses a multi-transmission zero balancing filter using coupling feeder lines to perform loading. The filter comprises symmetrical first and second differential input ports, symmetrical first and second differential output ports and symmetrical first and second branch loading ring resonators. The first and second differential input ports are respectively in cascade connection with first and second impedance conversion lines. The first and second differential output ports are respectively in cascade connection with third and fourth impedance conversion lines. The first impedance conversion line is loaded with a first feeder line. The third impedance conversion line is loaded with a second feeder line. The ring resonator part of the first branch loading ring resonator is coupled with the first and second feeder lines. The second impedance conversion line is loaded with a third feeder line. The fourth impedance conversion line is loaded with a fourth loader line. The ring resonator part of the second branch loading ring resonator is coupled with the third and fourth feeder lines. A first branch is loaded between the first and third feeder line. A second branch and a third branch are loaded between the second and fourth feeder lines. The filter is advantaged by high selectivity, high common-mode rejection and low loss.

Description

technical field [0001] The invention relates to the technical field of microwave communication, in particular to a multi-transmission zero-point balanced filter loaded by a coupled feeder. Background technique [0002] With the development of modern communication technology, balanced filters have received more and more attention due to their high immunity to environmental noise, but balanced filters with high common-mode rejection, high selectivity, and low loss are still The key points and difficulties of the research. In order to suppress the common mode, it can be realized by using GDS defect ground, symmetrical stub loading, introducing transmission path, slot line structure, etc. However, these methods do not improve the selectivity of the differential mode passband. To this end, some different methods are used to introduce transmission zeros, such as direct stub loading, source-load coupling, cascaded fourth-order structures, etc., which not only increase the complex...

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Problems solved by technology

The disadvantage is the large passband insertion loss, reaching 3.5dB

[0007] From the above analysis, although the existing structure can achieve high common-mode rejection or high selectivity or loss, it is still difficult to design a multi-transmission zero-point balanced filter with high selectivity, high common-mode rejection, and low loss.

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