An ultra-small balanced three-line coupled filter

Abstract

The invention discloses an ultra-small balanced three-line coupling filter, which adopts a single-layer microstrip structure, and the whole structure is centrally symmetrical. The filter consists of four feed lines, an eighth-wavelength three-wire coupling structure, eight chip capacitors, and metalized ground vias. The four feeders are respectively arranged on the outer sides of the two ends of the one-eighth wavelength three-wire coupling structure, and the four chip capacitors are respectively loaded on the inner sides of the two ends of the one-eighth wavelength three-wire coupling structure. One end of the other four chip capacitors is loaded on the outside of the three-wire coupling structure, and the other ends are respectively grounded through metalized through holes.

Description

technical field [0001] The invention relates to the field of microwave communication, in particular to an ultra-small balanced three-line coupling filter. Background technique [0002] With the development of wireless communication equipment and terminals toward the direction of functional diversification, on the one hand, the miniaturization requirements of each subsystem are put forward, and on the other hand, each subsystem is required to improve the immunity to environmental noise and electromagnetic interference. The filter system is a key subsystem to ensure the normal operation of wireless devices and terminals. The use of a balanced filter system is conducive to improving the ability of the entire system to respond to electromagnetic interference and environmental noise. However, the traditional balanced filter system has the problem of large size, which cannot meet the requirements of system miniaturization. Therefore, it is necessary to propose a miniaturized bala...

AI Technical Summary

Problems solved by technology

However, the above design methods are at least based on the half-wavelength structure, so the degree of size reduction is limited, and there is still room for further reduction to achieve an ultra-small balanced filter system

In addition to the size problem, some of the above designs also have problems such as high loss and narrow common-mode rejection frequency band, which affect the overall performance of the balanced filter system

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