Broadband high-selectivity balanced band-pass filter based on multimode resonators

Abstract

The present invention discloses a broadband high-selectivity balanced band-pass filter based on multimode resonators. The band-pass filter comprises an input port feeder, a first output port feeder, a second output port feeder, a first multimode resonator and a second multimode resonator which are arranged on the upper surface of a dielectric substrate, and a metal earth plate arranged on the lower surface of the dielectric substrate, wherein both the first and second multimode resonators are symmetric stub-loaded multimode resonators; wherein the input port feeder comprises symmetrically connected first and second input port feeders; the first multimode resonator comprises two quarter-wave resonators, and three open-ended symmetric loading units; the second multimode resonator comprises two quarter-wave resonators, and three open-ended symmetric loading units. The broadband balanced band-pass filter according to the present invention has advantages such as broad stopband, minimized size, high common-mode rejection, high selectivity and low costs, and is quite suitable for modern wireless communication systems.

Description

technical field [0001] The invention relates to the technical field of microwave passive devices, in particular to a broadband high-selectivity balanced 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. The balanced filter is an independent microwave passive device, which has higher environmental noise immunity, better dynamic range, and lower electric field interference than the single-port filter. The balanced filter realizes the passband range in the radio frequency circuit The function of internal differential mode signal transmission and common mode signal suppression plays an extremely important role in the construction of modern high-speed wireless ...

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Problems solved by technology

Although the design theory of this design method is relatively simple, because the structure needs to be loaded with lumped elements, the structure processing is complicated and the error increases

The bandwidth of the balanced filter designed from the outside is narrow, and the 3dB relative bandwidth is only 8.92%.

[0004] In 2012, Wenjie Feng and Wenquan Che published "Novel Wideband Differential Bandpass Filters Based on T-Sharped Structure" in IEEE Transaction.Microwave Theory Technique (vol.60, no.6, pp.1560-1568, 2012), proposing Based on the T-shaped structure to realize the balanced output of the signal and the band-pass characteristics of the dual-mode, although the structure of this design method is relatively simple, the common-mode rejection effect is only 14.5dB, and the differential-mode out-of-band rejection is poor

Although this design does not require a ground hole and the structure is relatively simple, the common-mode rejection is only limited to the corresponding differential-mode frequency band, the out-of-band rejection of both common-mode and differential-mode is poor, and the insertion loss is large

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