Microwave balanced variable filter

Abstract

The invention discloses a balanced variable filter, which comprises a first half-wavelength microwave transmission line, a second half-wavelength microwave transmission line and six variable capacitors, wherein the first half-wavelength microwave transmission line and the second half-wavelength microwave transmission line are in bilateral symmetry, the first variable capacitor, the second variable capacitor, the third variable capacitor and the fourth variable capacitor are the same in type and parameters, the fifth variable capacitor and the sixth variable capacitor are the same in type and parameters, each half-wavelength transmission line is in vertical symmetry, first ends of the first variable capacitor, the second variable capacitor, the third variable capacitor and the fourth variable capacitor are connected with four terminal points of the first half-wavelength microwave transmission line and the second half-wavelength microwave transmission line respectively, first ends of the fifth variable capacitor and the sixth variable capacitor are connected with middle points of the first half-wavelength microwave transmission line and the second half-wavelength microwave transmission line, second ends of the six variable capacitors are respectively grounded. By the aid of the technical scheme, the differential passband frequency of the balanced variable filter can be regulated by controlling capacitance values of the variable capacitors loaded in the terminal points; and high common-mode rejection degree of the balanced variable filter can be kept stable within the variable range of the differential passband frequency by regulating the capacitance values of the variable capacitors loaded in the middle points.

Description

technical field [0001] The invention relates to the field of microwave communication, in particular to a microwave balanced tunable filter. Background technique [0002] In recent years, balanced microwave circuits have gradually become a research hotspot in radio frequency microwave circuits and systems. The reason is that balanced circuits have many advantages: superior circuit stability, better anti-noise performance, higher harmonic suppression Wait. Filters are the core components of microwave wireless communication systems. In order to meet the development needs of the system, the topological structures of various balanced filters have been deeply studied at home and abroad. In order to achieve good differential passband response of microwave balanced filters while ensuring high common-mode rejection in the passband, various forms of resonators have been widely studied, such as coupled line resonators, multi-segment resonators, double-sided Parallel striplines, step ...

AI Technical Summary

Problems solved by technology

However, according to domestic and foreign literature reports, in the design of filters, frequency tunable technology and balanced topology have not been well combined, especially in the differential passband frequency adjustable range to achieve continuous and stable high common mode Inhibition has no clear solution

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