A dual-mode balun bandpass filter based on multimode resonators

Abstract

The invention discloses a multi-mode resonator based dual-mode balun bandpass filter, which comprises an input end feeder, a two-port output end feeder, a three-port output end feeder, a first multi-mode resonator, a second multi-mode resonator, a dielectric substrate and a metal grounding plate, wherein both the first multi-mode resonator and the second multi-mode resonator are symmetry plane branch loading multi-mode resonators; the input end feeder, the two-port output end feeder, the three-port output end feeder, the first multi-mode resonator and the second multi-mode resonator are located at the upper surface of the dielectric substrate, and the metal grounding plate is located at the lower surface of the dielectric substrate; the first multi-mode resonator comprises two quarter-wavelength resonators and two symmetry plane branch loading units, and the second multi-mode resonators comprises two quarter-wavelength resonators and two symmetry plane branch loading units. The balun bandpass filter disclosed by the invention is simple in structure, low in loss and good in selectivity, and has excellent port matching properties, thereby being extremely 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 dual-mode balun bandpass filter based on a 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 the key elements in 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 signal filt...

AI Technical Summary

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), proposing Two output ports are symmetrically placed on the ring resonator, and open-circuit stubs are introduced at the same time to achieve balanced output of the signal and dual-mode band-pass characteristics. However, due to the introduction of step impedance in this structure, the structure is no longer symmetrical. The balanced output performance of the balun filter is poor, and the size of the balun filter is large because no capacitive loading is introduced

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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