Broadband and low-fluctuation band-pass LC filter

Abstract

The invention provides a broadband and low-fluctuation band-pass LC filter. According to the filter, ordinary inductors are replaced by winding magnetic rings with small temperature drift, good stability, and high Q value, and 0805 packaging capacitors are employed so that the stability of electrical parameters is guaranteed, and the electrical performance index of the filter is greatly increased. Penetrating holes are arranged at four corners around a PCB so that input, output, and grounding signals can all be perfectly transmitted to the PCB and components. Besides, a transfer function expansion equation of the filter is designed based on the design principle of in-band fluctuation, standing waves, and optimal dimension, and the capacitors and the winding magnetic rings are arranged strictly according to the equation so that the filter is advantaged by small packaging, large bandwidth, low insertion loss, high rectangular degree, high stop-band suppression, low standing wave, and low in-band fluctuation.

Description

technical field [0001] The invention relates to the field of filters, in particular to a wide-band, low-fluctuation band-pass LC filter. Background technique [0002] With the development of radio frequency technology, the requirements for filter frequency indicators are becoming increasingly stringent. Some commonly used communication equipment transmit and receive channels need to use filters with larger bandwidths to meet the increasing amount of information transmission 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" filter with "good rectangular coefficient" in the 21.4MHz frequency band. Under the existing technology, it can only be realized with a surface acoustic wave filter, but With the increase of the frequency bandwidth, the insertion loss of the surface acoustic wav...

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Problems solved by technology

[0003] Generally speaking, it is not easy to realize a "broadband" filter with "good rectangular coefficient" in the 21.4MHz frequency band. Under the existing technology, it can only be realized with a surface acoustic wave filter, but With the increase of the frequency bandwidth, the insertion loss of the surface acoustic wave filter also increases, and the difficulty of realization is also increasing. At present, the existing surface acoustic wave filter can only achieve a maximum of 6- 8MHz bandwidth

[0004] At present, if this frequency point reaches a bandwidth of 12MHz, the corresponding LC filter has the following problems: if the Q value of the inductor is guaranteed, the minimum volume can only be 27mm*15mm*10mm; if it is reduced to the same volume, Then the parameters related to the Q value cannot be guaranteed.

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