阅读说明：本技术 一种短波吸收式低通滤波器 (Short wave absorption type low-pass filter ) 是由 赵智兵 陈向明 颜研 于 2020-07-20 设计创作，主要内容包括：本发明公开了一种短波吸收式低通滤波器,包括截止频率为30MHz的第一滤波器和第二滤波器,第一滤波器与第二滤波器并联连接,低通滤波器从左至右设有5个串联的第一电感,相邻两个第一电感之间连接有第二电感,第二电感的输出端连接有第一电容；第二滤波器从左至右设有5个串联的第二电容,相邻两个第二电容之间连接有第三电感,第三电感的末端接地,第二滤波器的输出端匹配连接有电阻。能够获得更好的滤波效果,保证反射回来的能量被高通滤波器吸收到假负载上,使得低通滤波器带外的输入驻波比和带内的输入驻波比几乎一致,从而避免了反射回来的能量对接收/发射链路带来次生的干扰与危害的不确定性。(The invention discloses a short-wave absorption type low-pass filter, which comprises a first filter and a second filter, wherein the cut-off frequency of the first filter is 30MHz, the first filter is connected with the second filter in parallel, the low-pass filter is provided with 5 first inductors which are connected in series from left to right, a second inductor is connected between every two adjacent first inductors, and the output end of each second inductor is connected with a first capacitor; the second filter is provided with 5 second capacitors connected in series from left to right, a third inductor is connected between every two adjacent second capacitors, the tail end of the third inductor is grounded, and the output end of the second filter is connected with a resistor in a matching manner. The method has the advantages that a better filtering effect can be obtained, the reflected energy is ensured to be absorbed on the dummy load by the high-pass filter, so that the out-of-band input standing wave ratio of the low-pass filter is almost consistent with the in-band input standing wave ratio, and the uncertainty of secondary interference and harm brought to a receiving/transmitting link by the reflected energy is avoided.)

1. The short-wave absorption type low-pass filter is characterized by comprising a first filter and a second filter, wherein the cut-off frequency of the first filter is 30MHz, the first filter is connected with the second filter in parallel, the low-pass filter is provided with 5 first inductors connected in series from left to right, a second inductor is connected between every two adjacent first inductors, and the output end of each second inductor is connected with a first capacitor;

the second filter is provided with 5 second capacitors connected in series from left to right, a third inductor is connected between every two adjacent second capacitors, the tail end of the third inductor is grounded, and the output end of the second filter is connected with a resistor in a matching manner.

2. The short-wave absorption low-pass filter according to claim 1, wherein an end of the first capacitor is grounded.

3. The short-wave absorption low-pass filter according to claim 1, wherein the third inductor and the resistor are grounded at their ends.

4. The short-wave absorption low-pass filter according to claim 1, wherein self-inductance coefficients of the first inductor are 330nH, 370nH, 260nH, 210nH, and 82nH, respectively, self-inductance coefficients of the second inductor are 16nH, 58nH, 240nH, and 42nH, respectively, and self-inductance coefficients of the third inductor are 120nH, and 170nH, respectively.

5. The short wave absorption low pass filter of claim 1, wherein the capacitance of the first capacitor is 150pF, 120pF, 62pF, and 91pF, respectively, and the capacitance of the second capacitor is 56pF, 47pF, 51pF, and 160pF, respectively.

6. The short-wave absorption low-pass filter according to claim 1, wherein the resistance of the resistor is 50 Ω.

Technical Field

The invention relates to the technical field of filters, in particular to a short-wave absorption type low-pass filter.

Background

In a short wave signal receiving link, the low-pass filter plays a role in inhibiting various out-of-band interferences, such as inhibiting intermediate frequency and image frequency and relieving the pressure of a back-end processing circuit; in a short-wave signal transmitting link, a low-pass filter is usually arranged behind a power amplifier to suppress output harmonic waves of the power amplifier, reduce interference on other electronic equipment on the same platform and improve electromagnetic compatibility of the platform.

As shown in fig. 3-4, which are a schematic diagram and a performance parameter curve of a conventional reflective low-pass filter, the conventional low-pass filter is based on a reflective architecture, and signals outside the band are transmitted back, which may cause secondary interference and harm to the receiving/transmitting chain.

Disclosure of Invention

In view of the above technical problems in the related art, the present invention provides a short-wave absorption low-pass filter, which can overcome the above disadvantages in the prior art.

In order to achieve the technical purpose, the technical scheme of the invention is realized as follows: a short-wave absorption type low-pass filter comprises a first filter and a second filter, wherein the cut-off frequency of the first filter is 30MHz, the first filter is connected with the second filter in parallel, the low-pass filter is provided with 5 first inductors which are connected in series from left to right, a second inductor is connected between every two adjacent first inductors, and the output end of the second inductor is connected with a first capacitor;

the second filter is provided with 5 second capacitors connected in series from left to right, a third inductor is connected between every two adjacent second capacitors, the tail end of the third inductor is grounded, and the output end of the second filter is connected with a resistor in a matching manner.

Further, the end of the first capacitor is grounded.

Further, the third inductor and the end of the resistor are grounded.

Further, the self-inductance coefficients of the first inductors are 330nH, 370nH, 260nH, 210nH and 82nH, the self-inductance coefficients of the second inductors are 16nH, 58nH, 240nH and 42nH, and the self-inductance coefficients of the third inductors are 120nH, 120nH and 170 nH.

Further, the appearance value of first electric capacity is 150pF, 120pF, 62pF and 91pF respectively, the appearance value of second electric capacity is 56pF, 47pF, 51pF and 160pF respectively.

Further, the resistance value of the resistor is 50 Ω.

The invention has the beneficial effects that: the filter has the advantages that a better filtering effect can be obtained, the filter comprises a low-pass filter with the cutoff frequency of 30MHz and a high-pass filter with the cutoff frequency of 30MHz, the output end of the high-pass filter is matched with a 50 omega dummy load, and the reflected energy is ensured to be absorbed on the dummy load by the high-pass filter, so that the input standing wave ratio outside the low-pass filter is almost consistent with the input standing wave ratio inside the low-pass filter, and the uncertainty of secondary interference and harm brought to a receiving/transmitting link by the reflected energy is avoided.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of a low pass filter according to an embodiment of the invention;

FIG. 2 is a low pass filter performance parameter plot according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a conventional reflective low pass filter according to the background of the invention;

fig. 4 is a graph of performance parameters of a conventional reflective low-pass filter according to the background of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.

As shown in fig. 1-2, the short-wave absorption type low-pass filter according to the embodiment of the present invention includes a low-pass filter with a cutoff frequency of 30MHz and a high-pass filter with a cutoff frequency of 30MHz, where the low-pass filter is connected in parallel with the high-pass filter, the low-pass filter is provided with 5 first inductors connected in series from left to right, a second inductor is connected between two adjacent first inductors, and an output end of the second inductor is connected with a first capacitor;

the high-pass filter is provided with 5 second capacitors connected in series from left to right, a third inductor is connected between every two adjacent second capacitors, the tail end of the third inductor is grounded, and the output end of the high-pass filter is connected with a resistor in a matching mode.

In one embodiment of the invention, the end of the first capacitor is grounded.

In a specific embodiment of the present invention, the third inductor and the end of the resistor are grounded.

In an embodiment of the present invention, the self-inductance coefficients of the first inductors are 330nH, 370nH, 260nH, 210nH, and 82nH, respectively, the self-inductance coefficients of the second inductors are 16nH, 58nH, 240nH, and 42nH, respectively, and the self-inductance coefficients of the third inductors are 120nH, and 170nH, respectively.

In a specific embodiment of the present invention, the first capacitors have capacitances of 150pF, 120pF, 62pF, and 91pF, respectively, and the second capacitors have capacitances of 56pF, 47pF, 51pF, and 160pF, respectively.

In one embodiment of the present invention, the resistance of the resistor is 50 Ω.

In order to facilitate understanding of the above-described technical aspects of the present invention, the above-described technical aspects of the present invention will be described in detail below in terms of specific usage.

In summary, with the adoption of the technical scheme of the invention, a better filtering effect can be obtained, the absorption type low-pass filter with the short wave frequency band has the cutoff frequency of 30MHz, the absorption type low-pass filter comprises a low-pass filter with the cutoff frequency of 30MHz and a high-pass filter with the cutoff frequency of 30MHz, the output end of the high-pass filter is matched with a 50 Ω dummy load, and the reflected energy is ensured to be absorbed on the dummy load by the high-pass filter, so that the input standing wave ratio outside the low-pass filter and the input standing wave ratio inside the low-pass filter are almost consistent, and the uncertainty of secondary interference and harm brought to a receiving/transmitting link by the reflected energy is avoided.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.