Micro-strip balanced filter

Abstract

The invention provides a micro-strip balanced filter which comprises two micro-strip band-pass filters. Structures of the two micro-strip band-pass filters are identical, the two micro-strip band-pass filters are symmetrically connected with each other, and source-load coupling structures generate transmission zero points inside edges of pass bands and stop bands under excitation actions of different-mode signals, so that the internal frequency selectivity of the pass bands is improved, and the stop bands are deepened; two common-mode signal transmission zero points are generated in each different-mode pass band by a corresponding central loaded stepped-impedance open-circuit branch and a folded oscillator loaded on a corresponding feeder, so that the common-mode rejection capacity is improved. The micro-strip balanced filter has the advantages of high frequency selectivity, low insertion loss, wide stop bands and compact structure.

Description

technical field [0001] The invention belongs to the field of electronic technology, and in particular relates to a microstrip balanced filter. Background technique [0002] Balanced circuits can efficiently suppress environmental noise and noise generated by active devices within the system, and are therefore widely used in modern communication systems. The balanced filter requires filtering characteristics when the differential mode signal is input, and has a high common mode rejection capability. The traditional balanced filter is composed of a single-port filter and two balun structures, which not only has a huge circuit area, but also has poor common-mode noise suppression ability. [0003] The use of double-sided parallel striplines can improve the common-mode rejection capability, but this will lead to a large system size; some scholars use a comb-line structure with tapped input, which can effectively suppress common-mode noise, but the resulting balanced filter isol...

AI Technical Summary

Problems solved by technology

The traditional balanced filter is composed of a single-port filter and two balun structures, which not only has a huge circuit area, but also has poor common-mode noise suppression ability

[0003] The use of double-sided parallel striplines can improve the common-mode rejection capability, but this will lead to a large system size; some scholars use a comb-line structure with tapped input, which can effectively suppress common-mode noise, but the resulting balanced filter isolation Low density, and the circuit design is complex, not easy to process

Images