Three-order electrical modulation band-pass filter with constant bandwidth

Abstract

The invention discloses a three-order electrical modulation band-pass filter with the constant bandwidth. The three-order electrical modulation band-pass filter with the constant bandwidth is high in selectivity, simple in electrical modulation control, smaller in overall size and capable of keeping absolute bandwidth fixation in the filter center frequency tunable process. According to the three-order electrical modulation band-pass filter with the constant bandwidth, an external Q value can be adjusted by adjusting a varactor loaded to a main transmission line, a uniform voltage feed is adopted for a first resonator, a second resonator and a third resonator, the restraint level outside a band at the low-frequency position can be flexibly adjusted by changing capacitance loaded to a band-stop unit, the three-order electrical modulation band-pass filter is easy to control, convenient to design and high in selectivity, and the absolute bandwidth keeps constant in the adjusting process; furthermore, on the premise of guaranteeing high selectivity and the harmonic wave suppression function, the design combining the band-stop unit and the band-pass filter is adopted, and thus the overall size of the filter is greatly reduced. The three-order electrical modulation band-pass filter with the constant bandwidth is suitable for being utilized and popularized in the technical field of filters.

Description

technical field [0001] The invention belongs to the technical field of filters, and in particular relates to a third-order electronically adjustable band-pass filter with constant bandwidth. Background technique [0002] With the development of wireless communication technology, especially the development of cognitive radio and electronic warfare, there are strict requirements for wireless transceivers in terms of broadband, miniaturization, multi-protocol, reconfigurable, etc., and there is an urgent need for wireless transceivers to break through the traditional The fixed mode of the communication standard realizes the free adjustment / switching of its carrier frequency, bandwidth, beam direction and other indicators within a certain range, so as to build a multi-mode communication link to improve the anti-interference ability and robustness, and increase the frequency spectrum. The purpose of utilization rate, expansion of communication capacity and quality of service. Si...

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Problems solved by technology

[0005] However, the above-mentioned design method has the following technical defects in the actual use process: first, the existing adjustable high-order filter is generally 4th order, and there are many adjustable parameters in the design process, which is extremely complicated to control; The method of combining band-stop filter and adjustable band-pass filter to improve selectivity will increase the size of the overall filter and limit its application scenarios

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