Cross-coupled structure-based high-order adjustable band-pass filter

Abstract

The present invention discloses a cross-coupled structure-based high-order adjustable band-pass filter and belongs to the radio frequency device field. The cross-coupled structure-based high-order adjustable band-pass filter of the present invention comprises a dielectric substrate; the top surface of the dielectric substrate is provided with a metal microstrip structure; the bottom surface of the dielectric substrate is provided with a metal grounding plate; and the metal microstrip structure includes two feed lines which are in bilateral symmetry and four tunable resonators which are arranged between the two feed lines. Based on reasonable design structure, the four-order tunable band-pass filter has a constant absolute bandwidth. According to the filter, symmetrical transmission zero points are realized based on a cross-coupled structure, so that the selectivity of frequencies can be effectively improved; the insertion loss of an adjustment range can be effectively decreased; and high attenuation characteristics within stop bands can be realized. The cross-coupled structure-based high-order adjustable band-pass filter provided by the invention is applied to high-level design and is of practical significance.

Description

technical field [0001] The invention relates to the field of radio frequency devices, in particular to a high-order electrically tunable bandpass filter with a cross-coupling structure. Background technique [0002] At present, many tunable microstrip filters used to increase the flexibility of radio frequency filters, as a basic device for radio frequency signal processing, are widely used in multi-band and software radio systems. In order to increase passband selectivity, high order filters are a common solution. [0003] For the design of high-order filters, corresponding methods are also provided in some literatures. K.T.Park et al. in "Lowvoltage tunable narrow bandpass filter using cross-coupled stepped-impedance resonator with active capacitance circuit" ("Low voltage tunable narrow bandpass filter with cross-coupled step resonator with active capacitance circuit") A fourth-order tunable filter is proposed by using cross-coupled step resonators; however, the electri...

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Problems solved by technology

K.T.Park et al. in "Lowvoltage tunable narrow bandpass filter using cross-coupled stepped-impedance resonator with active capacitance circuit" ("Low voltage tunable narrow bandpass filter with cross-coupled step resonator with active capacitance circuit") A fourth-order tunable filter is proposed by using cross-coupled step resonators; however, the electric and magnetic properties of the resonators in the tunable filter are difficult to control, so the passband and transmission zero of the tunable filter have inconsistencies. too consistent, and its bandwidth is not constant

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