Double-passband filter

Abstract

The invention discloses a double-passband filter. The double-passband filter comprises a three-order double-mode resonator, input / output feeder lines, a medium substrate and a metal floor, wherein the three-order double-mode resonator is of a symmetrical structure, the medium substrate is provided with a first grounding through hole, a second grounding through hole and a third grounding through hole, the three-order double-mode resonator comprises two first-order double-mode resonance units, two third-order double-mode resonance units and a second-order double-mode resonance unit, each first-order double-mode resonance unit is formed in the mode that a short circuit transmission line is in cascade connection with a spiral open circuit transmission line through a closed rectangular ring transmission line, each third-order double-mode resonance unit is formed in the mode that a short circuit transmission line is in cascade connection with a spiral open circuit transmission line through a closed rectangular ring transmission line, a half-wavelength stepped impedance double-mode resonance unit serves as the second-order double-mode resonance unit and comprises a two low-impedance transmission lines and a high-impedance transmission line of a spiral line structure, and two passbands of the filter are composed of the first-order resonant mode of the three-order double-mode resonator and the second-order resonant mode of the three-order double-mode resonator respectively. According to the double-passband filter, a hybrid cross coupling structure is adopted, and three transmission zeros can be generated at the position near each passband.

Description

technical field [0001] The invention belongs to the technical field of microwave communication, and in particular relates to a double-passband filter. Background technique [0002] With the rapid development of wireless communication systems, communication standards such as GSM, CDMA, WCDMA, TD-SCDMA, WIMAX, and WLAN have been widely used. As an essential and important device in the RF front-end, the filter is used to separate frequencies, that is, to pass signals of a certain frequency and block signals of other frequencies. An ideal filter should satisfy the passband without attenuation and at the cutoff frequency The internal attenuation is infinite. The design performance of the filter directly affects the various indicators of the communication system, so how to design a filter with high selectivity, high isolation, and miniaturization is becoming more and more important. [0003] In the traditional dual-passband filter design, increasing the order of the filter is of...

AI Technical Summary

Problems solved by technology

The above-mentioned single technology is used in the design of related dual-passband filters reported so far. The dual-passband filter using hybrid cross-coupling technology has not been reported yet. Hybrid cross-coupling technology can well combine cross-coupling and hybrid electromagnetic coupling. technology, which can generate more transmission zeros without increasing the size of the dual-passband filter, so that the dual-passband filter has higher selectivity and isolation between passbands

Images