A Multi-transmission Zero Balanced Filter Loaded by Coupled Feeder

Abstract

The invention discloses a multi-transmission zero-point balanced filter loaded by a coupled feeder, including symmetrical first and second differential input ports, symmetrical first and second differential output ports, and symmetrical first and second branch-loaded ring resonators ; The first and second differential input ports are respectively cascaded with first and second impedance transformation lines, the first and second differential output ports are respectively cascaded with third and fourth impedance transformation lines, and the first impedance transformation line is loaded with a first feeder line, The third impedance transformation line is loaded with the second feeder line, the ring resonator part of the first branch loaded ring resonator is coupled with the first and second feeder lines, the second impedance transformation line is loaded with the third feeder line, and the fourth impedance transformation line is loaded with The fourth feeder, the ring resonator part of the ring resonator loaded by the second branch is coupled with the third and fourth feeders, the first branch is loaded between the first and third feeders, and the second and third branches are loaded between the second and fourth feeders . The invention has the advantages of high selectivity, high common mode rejection, low differential loss and the like.

Description

Technical field [0001] The invention relates to the technical field of microwave communication, in particular to a multi-transmission zero-point balance 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 higher immunity to environmental noise. However, balanced filters with high common mode rejection, high selectivity, and low loss are still The focus and difficulty of the research. In order to suppress the common mode, GDS defect ground, symmetric branch loading, introduction of transmission path, slot line structure, etc. can be used to achieve. But these methods did not improve the selectivity of the differential mode passband. For this reason, a number of different methods are used to introduce transmission zeros, such as direct branch loading, source-load coupling, cascaded fourth-order structure, etc., which not only increase the compl...

AI Technical Summary

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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