Electronically adjustable four-pass band filter based on double-layer resonators

Abstract

The invention discloses an electronically adjustable four-passband filter based on a double-layer resonator, which mainly solves the problems of the traditional electronically adjustable filter with a small number of passbands, variable bandwidth of the adjustable passband, poor out-of-band suppression and large volume . It includes a pair of parallel coupled feeders (1) and a pair of adjustable ladder impedance resonators (2, 3) arranged on the upper microstrip dielectric substrate (7), and a stub loader arranged on the lower microstrip dielectric substrate (8). The resonator (4) and two DC bias circuits (5, 6); the two DC bias circuits (5, 6) are respectively connected to the two ends of the adjustable ladder impedance resonators (2) and (3), respectively The continuous adjustment of the third passband and the fourth passband is realized; the stub-loaded resonator (4) realizes the fixing of the first passband and the second passband. The invention has small size, high out-of-band suppression, can realize four passbands, and realizes continuous adjustment of the third passband and the fourth passband under the condition that the bandwidth remains basically unchanged, and can be used in wireless communication systems.

Description

technical field [0001] The invention belongs to the technical field of microwave devices, in particular to a microstrip electrically adjustable four-pass band filter, which can be used for a radio frequency front end of a wireless communication system. Background technique [0002] With the rapid development of modern communication technology, the contradiction of spectrum resource congestion has become increasingly prominent. In order to efficiently utilize limited spectrum resources, it is usually required that the RF front-end, such as filters, have the characteristics of fast tuning. The electric tuning filter changes the capacitance value of the varactor diode by controlling the DC bias voltage, thereby changing the resonant frequency and realizing fast switching at different operating frequencies. In addition, in order to achieve different service requirements in multiple frequency bands, the wireless communication system needs to use filters to select in-band working...

AI Technical Summary

Problems solved by technology

The current electronically tuned filters are mainly concentrated in the fields of single passband and double passband, and the three-passband or even four-passband electronically tuned filters are more difficult to implement due to their complex structure.

[0003] In January 2009, E.E.Djoumessi et al. published "Varactor-tuned quarter-wavelength dual-bandpass filter" in the IET Microwave Antennas Propagation journal (Vol.3, no.1, pp.117–124, 2009), proposing an electronic Adjustable dual passband microstrip filter, the filter can realize the continuous electrical adjustment of two passbands, but it is difficult to extend the structure to more passbands; in 2009, Ko-Wen Hsu et al. presented at Microwave symposiumDigest conference (pp. 1041-1044, 2009.) published "Design of a Novel Four-Band MicrostripBandpass Filters using Double Layered substrate", and proposed a four-band microstrip filter based on a double-layer structure, which can realize four Passband, but can not achieve fast adjustable frequency

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