LC filter with wide band, high rectangle coefficient and high suppression band-pass

Abstract

The invention discloses an LC filter with a wide band, a high rectangle coefficient and a high suppression band-pass. The high suppression band-pass LC filter comprises a filter cavity, a printed circuit board, capacitors, hollow-core coils and an insulator, wherein the printed circuit board is arranged inside the cavity, the hollow-core coil is sleeved with an insulating varnish wrap of a low dielectric constant, and the capacitor and the hollow-core coil are fixed on the printed circuit board through tin soldering; the insulator is fixed inside the cavity, and one end of the insulator is welded on the printed circuit board; the LC filter is of an eight-order LC filter structure, and a topological structure of the LC filter is provided with 12 LC resonant circuit formed by the capacitors and the hollow-core coils, and each LC resonant circuit is formed by a capacitor and a hollow-core coil. The performance and the volume of the filter are taken into consideration, the LC filter has the advantages of small package, large bandwidth, low fluctuation and high stopband rejection, and meanwhile the standing wave and the insertion loss are small.

Description

technical field [0001] The invention relates to a filter, in particular to a band-pass LC filter with wide frequency band, high rectangular coefficient and high rejection. Background technique [0002] With the development of radio frequency technology, the requirements for the filter frequency index are becoming increasingly stringent. Some commonly used communication equipment transmit and receive channels need to use filters with higher square coefficient and higher rejection to meet the increasingly high clutter filtering requirements. , information transmission capacity and wide frequency bandwidth, but at the same time, the requirements for volume are becoming more and more stringent, and the volume must be developed towards "miniaturization". [0003] Generally speaking, it is not easy to realize a broadband high-rejection filter in the 1800MHz frequency band. Under the existing technology, it can only be realized with a cavity filter. In this frequency band, the volu...

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Problems solved by technology

[0003] Generally speaking, it is not easy to realize a broadband high-rejection filter in the 1800MHz frequency band. Under the existing technology, it can only be realized with a cavity filter. In this frequency band, the volume of the cavity filter Larger, it is difficult to be used in engineering applications of complex products. With the increase of bandwidth, the size of the cavity filter also increases, and the realization is more difficult. Moreover, the existing cavity filter is at 1800MHz frequency The lower bandwidth can only achieve a bandwidth not greater than 800MHz

[0004] At present, if this frequency point reaches -0.5dB bandwidth ≥ 1000MHz and out-of-band rejection ≥ 35dBc at 1100MHz & ≥ 35dBc at 2500MHz, the corresponding LC filter has the following problems: If the Q value of the inductor is guaranteed, the volume is the smallest It can achieve 45.4mm*10mm*7mm; if it is reduced to the same volume, the parameters related to the Q value cannot be guaranteed

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