Miniature triple-band band-pass filter based on embedded quarter-wavelength resonators

Abstract

The invention discloses a miniature triple-band band-pass filter based on embedded quarter-wavelength resonators, comprising two embedded quarter-wavelength resonators arranged symmetrically, two split-ring resonators, two 0-degree tap feeders, and a metalized via V arranged between the two embedded quarter-wavelength resonators. Through mutual offset of magnetic coupling and electric coupling and by adoption of the 0-degree tap feeder structure, the selectivity and the degree of isolation between pass bands of the filter are improved greatly. The miniature triple-band band-pass filter of the invention has the advantages of low weight, small size, high reliability, excellent performance, good temperature stability, mass production, low cost and the like, and is applicable to multi-band multi-service wireless communication systems in different working environments.

Description

technical field [0001] The invention relates to a filter, especially a miniaturized three-band bandpass filter based on an embedded quarter-wavelength resonator. Background technique [0002] In recent years, multi-band multi-service wireless communication systems have developed rapidly. As a key device in the RF front-end circuit of wireless communication systems, the design of multi-band filters that meet application needs has become a research hotspot. Filters with miniaturization, multiple passbands, high selectivity, and high isolation are in extremely urgent demand. [0003] Document 1 (Advanced triple‐bandbandpass filter using tri‐sectionSIR, IET Electron.Lett.vol.44, no.4, pp.295‐296, Feb.2008) discloses a three-section ladder impedance line to achieve a triple bandpass filter. The structure of the filter is simple and the size is small, but its resonant frequencies affect each other, each passband cannot be controlled independently, and the selectivity of each pass...

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Problems solved by technology

[0003] Document 1 (Advanced triple‐bandbandpass filter using tri‐sectionSIR, IET Electron.Lett.vol.44, no.4, pp.295‐296, Feb.2008) discloses a three-section ladder impedance line to achieve a triple bandpass filter. The structure of the filter is simple and the size is small, but its resonant frequencies affect each other, each passband cannot be controlled independently, and the selectivity of each passband is poor, and the isolation between passbands is not high; Literature 2 (Compactdual‐modetriple ‐bandbandpass filters using three pairs of degenerate modes inaring resonator, IEEETrans.Microw.TheoryTech., vol.59, no.5, pp.1222‐1229, May 2011) discloses a filter that utilizes the evanescent mode of a ring resonator to realize a three-band pass, the filter structure Simple, only one ring resonator is used to realize three passbands, but the passbands of the filter cannot be controlled separately, and the in-band frequency response and out-of-band selectivity of each passband are poor, and the isolation between passbands is not high. The notch characteristic of the stop band leads to low stop band suppression; Document 3 (Compact tri-bandband pass filter based on resonators with U-folded coupled-line, IEEE Microw.Wireless Compon. Lett., vol.23, no.5, pp.258-260, May 2013) discloses A three-band bandpass filter in which multiple sets of resonators are cascaded, and each set of resonators produces a passband. Each passband of the filter can be independently controlled by adjusting each cascaded resonator, but the volume is relatively large

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