Electrically tunable filter of varactor

Abstract

The invention discloses an electrically tunable filter of a varactor, comprising an input micro-strip line, a first micro-strip resonator, a second micro-strip resonator and an output micro-strip line, wherein the first micro-strip resonator and the second micro-strip resonator open outwards and are arranged side by side in a mirror image manner, the adjacent parts of the first micro-strip resonator and the second micro-strip resonator form direct coupling; the input micro-strip line and the output micro-strip line are respectively arranged below the first micro-strip resonator and the second micro-strip resonator and are arranged side by side in a mirror image manner, the tail ends of the input micro-strip line and the output micro-strip line both deflect for 90 degrees along the direction away from the first micro-strip resonator and the second micro-strip resonator and two deflected parts are mutually parallel to form cross coupling and the symbol of the cross coupling is opposite to the symbol of the direct coupling. The transfer function of the electrically tunable filter of the varactor generates a transmission zero point and has the like elliptic function feature, and therefore the filter has good rectangle coefficient, and the filtering performance is improved.

Description

technical field [0001] The invention relates to the technical field of signal processing in the electronics industry, and in particular to a variable capacitance tube electrically adjustable filter. Background technique [0002] Electrically tunable filters are used in occasions where frequency changes, especially in the field of radar detection, to filter signals, so as to obtain a relatively pure spectrum and improve the anti-interference ability of the system. Electrically tunable filters are generally classified into two types: Yttrium Iron Garnet (YIG for short) electrically tunable filters and varactor electrically tunable filters. YIG electric tunable filter has a high quality factor, but due to the influence of hysteresis effect, its tuning speed is slow, so it cannot be applied to frequency agility occasions. The tuning speed of the varactor electronically tuned filter is fast, which can meet the needs of agile frequency conversion, and a high quality factor can be...

AI Technical Summary

Problems solved by technology

[0004] In the process of realizing the present invention, the applicant realizes that the following technical defects exist in the prior art: the existing varactor electric tuning filter usually adopts Butterworth synthesis or Chebyshev synthesis, and the rectangular coefficient of the design scheme of these filters is not good, specifically Generally speaking, there is no steep edge, so the filtering effect on the sideband is not good, so it cannot meet the demand in occasions with high requirements for sideband suppression

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