Broadband three-mode Balun band-pass filter based on E multi-mode resonators

Abstract

The invention discloses a broadband three-mode Balun band-pass filter based on E multi-mode resonators, comprising an input feeder, a dual-port output feeder, a three-port output feeder, a first E multi-mode resonator, a second E multi-mode resonator, a dielectric substrate, and a metal ground plate. The first and second E multi-mode resonators are symmetrical stub-loaded multi-mode resonators. The input feeder, the dual-port output feeder, the three-port output feeder, the first E multi-mode resonator and the second E multi-mode resonator are disposed on the upper surface of the dielectric substrate, and the metal ground plate is disposed on the lower surface of the dielectric substrate. The first E multi-mode resonator includes two quarter-wave resonators and a symmetrical stub loading unit. The second E multi-mode resonator includes two quarter-wave resonators and a symmetrical stub loading unit. The broadband three-mode Balun band-pass filter has the advantages of simple structure, low loss, good selectivity and good port matching property, and is very applicable to a modern wireless communication system.

Description

technical field [0001] The invention relates to the technical field of microwave passive devices, in particular to a wideband balun bandpass filter based on an E-type multimode resonator. Background technique [0002] In recent years, with the development of Modular Building Block (MBB) and Monolithic Microwave Integrated Circuit (MMIC), low cost, high integration, and miniaturization have become an important part of the integrated design of modern wireless communication systems. very important consideration. In order to achieve these design goals, new passive microwave devices with multifunctional integration features are becoming a research hotspot at home and abroad, and one of the very hot topics is the design of high-performance balun filters. [0003] The balun filter is an independent microwave passive device, which functionally realizes the effective combination of the filter and the balun in the radio frequency circuit, that is to say, the balun filter has both sig...

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Problems solved by technology

Although the design theory of this design method is relatively simple, because the structure introduces a ladder impedance resonator, the bandwidth of the designed balun filter is relatively narrow.

In addition, since the circuit involves three-wire coupling, it is necessary to adopt a zigzag coupling form to enhance the coupling strength between the ladder impedance resonator and the main transmission line, so the structure of the balun filter is more complicated and the circuit size is also larger

[0005] In 2007, Eul-Young Jung and Hee-Yong Hwang published "A Balun-BPF Using a Dual Mode Ring Resonator" in IEEE Microwave Wireless Components Letters (vol.17, no.9, pp.652-654, 2007) , it is proposed to symmetrically place two output ports on the ring resonator, and at the same time introduce an open-circuit stub to achieve a balanced output of the signal and a dual-mode band-pass characteristic. However, due to the introduction of a step impedance in this structure, the structure is no longer Symmetrical, resulting in poor balanced output performance of the balun filter, and because no capacitive loading is introduced, the size of the balun filter is large

Although the balun designed by this design method has the advantage of small size in the low frequency band, it also has the disadvantages of large loss, narrow bandwidth, and poor amplitude and phase matching due to the related characteristics of lumped elements.

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