Tunable band-stop filter of constant absolute bandwidth based on modular structure

Abstract

The invention discloses a tunable band-stop filter of constant absolute bandwidth based on a modular structure, which comprises a micro-band structure in the upper layer, a medium substrate in the middle layer and a grounded metal plate in the lower layer. The filter can consist of one module unit or a plurality of module units, each of which comprises two resonators and a main transmission line;the two resonators are both half-wavelength resonators which have the same structure, and the two resonators are symmetrical about a central vertical axis in the micro-band structure; the main transmission line comprises a coupling part and a non-coupling part; the coupling part consists of a seventh micro-band line, an eighth micro-band line and a ninth micro-band line, and the lines are sequentially connected to form an n-shaped structure which is arranged at the inside of an n-shaped structure of the coupling part of the resonators; variable capacitance diodes of the two resonators are setwith the same bias voltage; and the filter can be applied to various reconfigurable radio frequency front-end circuits and has the characteristics of constant absolute bandwidth when the frequency istuned. By cascading two or more module units, a tunable band-stop filter of constant absolute bandwidth can be obtained, the frequency selectivity of which is higher.

Description

technical field [0001] The invention relates to a band-stop filter with adjustable center frequency, in particular to an adjustable band-stop filter based on a modular structure, the absolute bandwidth is constant when the center frequency is tuned, and can be applied to a radio frequency front-end circuit. Background technique [0002] The development of modern ultra-wideband radar and wireless communication requires high-performance reconfigurable RF subsystems. For example, the development of mobile communication requires miniaturized, multi-standard, multi-mode, multi-band transceivers. In order to meet this requirement, the RF front-end needs to be based on operating mode to adjust its operating frequency and bandwidth. This type of RF front-end requires a variety of RF tunable filters to select useful signals and suppress interfering signals, among which RF tunable band-stop filters are an important category of RF tunable filters. In the RF front-end circuits of multi...

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Problems solved by technology

[0005] The purpose of the present invention is to solve the problems existing in the prior art, to provide an adjustable band-stop filter based on a modular structure and having a constant absolute bandwidth when the center frequency is tuned; an adjustable band-stop filter based on a modular structure with a constant absolute bandwidth The filter has the characteristics of constant absolute bandwidth; at the same time, it has the characteristics of modular design, and directly cascades two or more adjustable band-stop filter module units to obtain a band-stop filter with higher frequency selectivity; based on modular The adjustable band-stop filter with constant absolute bandwidth of the structure can solve the problem that the absolute bandwidth of the stop band changes when the center frequency is tuned and the problem that high-order filter designs cannot be directly cascaded

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