CN106454190B - Band-pass filter with broadband high out-of-band rejection - Google Patents
Band-pass filter with broadband high out-of-band rejection Download PDFInfo
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
- H04N7/102—Circuits therefor, e.g. noise reducers, equalisers, amplifiers
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Abstract
The invention discloses a band-pass filter with high band rejection in broadband, which comprises a third-order high-pass filter, a third-order low-pass filter, a first high-frequency low-pass filter and a second high-frequency low-pass filter, wherein the third-order high-pass filter is connected with the third-order low-pass filter through the first high-frequency low-pass filter, the third-order low-pass filter is connected with the second high-frequency low-pass filter, the initial frequency of the third-order high-pass filter is 110MHz, and the cut-off frequency of the third-order low-pass filter is 862MHz. The broadband band-pass filter with high out-of-band rejection has high out-of-band rejection, can resist various strong interferences in the Cable digital television signals, such as the interference of the uplink strong signals of the low-frequency EOC and the Cable modem, the interference of the MOCA and the high-frequency EOC, the WIFI interference and the like, greatly improves the quality of the Cable digital television signals, has ingenious circuit design and low cost, and has good application prospect.
Description
Technical Field
The invention relates to the technical field of signal filtering processing, in particular to a broadband high out-of-band rejection band-pass filter.
Background
Various strong interferences exist in the Cable digital television network, such as uplink strong signals of low-frequency EOC and Cable modem, interference of MOCA and high-frequency EOC, WIFI interference and the like, so that the signal quality of the Cable digital television is affected, and how to design a filter to inhibit various strong interferences and improve the signal quality is a problem which needs to be solved currently.
Disclosure of Invention
The invention aims to solve the problems that various strong interferences exist in the existing cable digital television network and the signal quality of the cable digital television is affected. The broadband band-pass filter with high out-of-band rejection has high out-of-band rejection, can resist various strong interferences in the Cable digital television signals, such as the uplink strong signals of low-frequency EOC and Cable modem, the interference of MOCA and high-frequency EOC, WIFI interference and the like, greatly improves the quality of the Cable digital television signals, has ingenious circuit design and low cost, has good application prospect, and is widely applied to Cable digital set-top box products of companies in the presence of the front.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a bandpass filter with wideband high out-of-band rejection, characterized by: comprises a third-order high-pass filter, a third-order low-pass filter, a first high-frequency low-pass filter and a second high-frequency low-pass filter, wherein the third-order high-pass filter is connected with the third-order low-pass filter through the first high-frequency low-pass filter, the third-order low-pass filter is connected with the second high-frequency low-pass filter,
the initial frequency of the third-order high-pass filter is 110MHz, and the cutoff frequency of the third-order low-pass filter is 862MHz.
The aforementioned band-pass filter with high out-of-band rejection for broadband is characterized in that: the third-order high-pass filter and the third-order low-pass filter both adopt resonance absorption structures.
The aforementioned band-pass filter with high out-of-band rejection for broadband is characterized in that: the third-order high-pass filter comprises a first capacitor C1, a second capacitor C2 and a third capacitor C3 which are connected in series, wherein the anode of the last capacitor is connected with the anode of the next capacitor, the anode of the first capacitor C1 is connected with the anode of a fourth capacitor C4, the anode of the fourth capacitor C4 is connected with the ground through a first inductor L1, the anode of the second capacitor C2 is connected with the anode of a fifth capacitor C5, the anode of the fifth capacitor C5 is connected with the ground through a second inductor L2, the anode of the third capacitor C3 is directly connected with the ground through a third inductor L3, the anode of the first capacitor C1 is used as the input end of the third-order high-pass filter, and the anode of the third capacitor C3 is used as the output end of the third-order filter to be connected with the input end of the first high-frequency low-pass filter.
The aforementioned band-pass filter with high out-of-band rejection for broadband is characterized in that: the first high-frequency low-pass filter comprises a fourth inductor L4 and a sixth capacitor C6, one end of the fourth inductor L4 is used as an input end of the first high-frequency low-pass filter to be connected with the third-order high-pass filter, the other end of the fourth inductor L4 is used as an output end of the first high-frequency low-pass filter to be connected with the input end of the third-order low-pass filter, the other end of the fourth inductor L4 is further connected with the negative electrode of the sixth capacitor C6, and the positive electrode of the sixth capacitor C6 is connected with the ground.
The aforementioned band-pass filter with high out-of-band rejection for broadband is characterized in that: the third-order low-pass filter comprises a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9 which are connected in series, wherein the negative electrode of the last capacitor is connected with the positive electrode of the next capacitor, the two electrodes of the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 are respectively connected with a fifth inductor L5, a sixth inductor L6 and a seventh inductor L7 in parallel, the positive electrodes of the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 are respectively connected with the negative electrodes of a tenth capacitor C10, an eleventh capacitor C11 and a twelfth capacitor C12, the positive electrodes of the tenth capacitor C10, the eleventh capacitor C11 and the twelfth capacitor C12 are all connected with the ground, the negative electrode of the seventh capacitor C7 is used as the input end of the third-order low-pass filter to be connected with the first high-frequency low-pass filter, and the positive electrode of the ninth capacitor C9 is used as the output end of the third-order low-pass filter to be connected with the input end of the second high-frequency low-pass filter.
The aforementioned band-pass filter with high out-of-band rejection for broadband is characterized in that: the second high-frequency low-pass filter comprises an eighth inductor L8 and a thirteenth capacitor C13, one end of the eighth inductor L8 is used as an input end of the second high-frequency low-pass filter to be connected with the third-order low-pass filter, the other end of the fourth inductor L4 is used as an output end of the second high-frequency low-pass filter, the other end of the eighth inductor L8 is also connected with a negative electrode of the thirteenth capacitor C13, and an anode of the thirteenth capacitor C13 is connected with the ground.
The aforementioned band-pass filter with high out-of-band rejection for broadband is characterized in that: the inductors in the third-order high-pass filter, the third-order low-pass filter, the first high-frequency low-pass filter and the second high-frequency low-pass filter can be hollow wire wound inductors, patch high-frequency wire wound inductors or patch high-frequency ceramic inductors.
The beneficial effects of the invention are as follows: the broadband band-pass filter with high out-of-band rejection has high out-of-band rejection, can resist various strong interferences in the Cable digital television signals, such as the interference of the uplink strong signals of the low-frequency EOC and the Cable modem, the interference of the MOCA and the high-frequency EOC, the WIFI interference and the like, greatly improves the quality of the Cable digital television signals, has ingenious circuit design and low cost, and has good application prospect.
Drawings
Fig. 1 is a schematic circuit diagram of a wideband high out-of-band rejection bandpass filter of the invention.
Detailed Description
The invention will be further described with reference to the drawings.
As shown in fig. 1, the band-pass filter with broadband high out-of-band rejection of the present invention includes a third-order high-pass filter, a third-order low-pass filter, a first high-frequency low-pass filter, and a second high-frequency low-pass filter, the third-order high-pass filter is connected with the third-order low-pass filter through the first high-frequency low-pass filter, the third-order low-pass filter is connected with the second high-frequency low-pass filter,
according to the band-pass filter, the low-frequency EOC and Cable modem uplink frequency is smaller than 65MHz, the Cable television digital signal is 110-862MHz, the MOCA and high-frequency EOC signals are more than 970MHz, the WIFI signal is near 2.4GHz, the low-frequency EOC and Cable modem uplink frequency is greatly filtered, the Cable television digital signal is 110-862MHz, the signals lower than 65MHz and the signals exceeding 970MHz are greatly filtered, the receiving of the Cable signals can be ensured to the greatest extent, the interference of out-of-band signals is avoided, the initial frequency of the third-order high-pass filter is 110MHz, the cut-off frequency of the third-order low-pass filter is 862MHz, the first high-frequency low-pass filter and the second high-frequency low-pass filter play roles in inhibiting signals at the high frequency end, the impedance matching function is achieved, and specific inductance parameters can be selected and adjusted according to actual needs.
The third-order high-pass filter and the third-order low-pass filter both adopt resonance absorption structures, the steep degree of the edge of the filter is greatly increased, and meanwhile, in order to improve the ESD performance, the third stage of the third-order high-pass filter adopts inductance direct grounding treatment.
The third-order high-pass filter comprises a first capacitor C1, a second capacitor C2 and a third capacitor C3 which are connected in series, wherein the anode of the last capacitor is connected with the anode of the next capacitor, the anode of the first capacitor C1 is connected with the anode of a fourth capacitor C4, the anode of the fourth capacitor C4 is connected with the ground through a first inductor L1, the anode of the second capacitor C2 is connected with the anode of a fifth capacitor C5, the anode of the fifth capacitor C5 is connected with the ground through a second inductor L2, the anode of the third capacitor C3 is directly connected with the ground through a third inductor L3, the anode of the first capacitor C1 is used as the input end of the third-order high-pass filter, and the anode of the third capacitor C3 is used as the output end of the third-order filter to be connected with the input end of the first high-frequency low-pass filter.
The first high-frequency low-pass filter comprises a fourth inductor L4 and a sixth capacitor C6, one end of the fourth inductor L4 is used as an input end of the first high-frequency low-pass filter to be connected with the third-order high-pass filter, the other end of the fourth inductor L4 is used as an output end of the first high-frequency low-pass filter to be connected with the input end of the third-order low-pass filter, the other end of the fourth inductor L4 is further connected with the negative electrode of the sixth capacitor C6, and the positive electrode of the sixth capacitor C6 is connected with the ground.
The third-order low-pass filter comprises a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9 which are connected in series, wherein the negative electrode of the last capacitor is connected with the positive electrode of the next capacitor, the two electrodes of the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 are respectively connected with a fifth inductor L5, a sixth inductor L6 and a seventh inductor L7 in parallel, the positive electrodes of the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 are respectively connected with the negative electrodes of a tenth capacitor C10, an eleventh capacitor C11 and a twelfth capacitor C12, the positive electrodes of the tenth capacitor C10, the eleventh capacitor C11 and the twelfth capacitor C12 are all connected with the ground, the negative electrode of the seventh capacitor C7 is used as the input end of the third-order low-pass filter to be connected with the first high-frequency low-pass filter, and the positive electrode of the ninth capacitor C9 is used as the output end of the third-order low-pass filter to be connected with the input end of the second high-frequency low-pass filter.
The second high-frequency low-pass filter comprises an eighth inductor L8 and a thirteenth capacitor C13, one end of the eighth inductor L8 is used as an input end of the second high-frequency low-pass filter to be connected with the third-order low-pass filter, the other end of the fourth inductor L4 is used as an output end of the second high-frequency low-pass filter, the other end of the eighth inductor L8 is also connected with a negative electrode of the thirteenth capacitor C13, and an anode of the thirteenth capacitor C13 is connected with the ground.
As known, the suppression capability of the filter circuit is related to the Q value of the adopted inductor, the larger the Q value is, the smaller the insertion loss is, the larger the out-of-band suppression is, the smaller the Q value is, the insertion loss is larger, and the out-of-band suppression is poor, so that the inductors in the third-order high-pass filter, the third-order low-pass filter, the first high-frequency low-pass filter and the second high-frequency low-pass filter can adopt air core wire wound inductors, patch high-frequency wire wound inductors or patch high-frequency ceramic inductors, the most commonly used patch high-frequency wire wound inductors are taken as examples, the Q value at 100MHz is about 100 GHz at 30 and 1GHz, the insertion loss is better near the edges of the 110MHz and 862MHz filters, the insertion loss can be controlled within 1 dB, and the low frequency end below 65MHz of the out-of-band suppression exceeds 45dB and the high frequency end above 970MHz exceeds 40dB.
In summary, the band-pass filter with high out-of-band rejection in the broadband has high out-of-band rejection, can resist various strong interferences in the Cable digital television signals, such as the uplink strong signals of low-frequency EOC and Cable modem, the interference of MOCA and high-frequency EOC, WIFI interference and the like, greatly improves the quality of the Cable digital television signals, has ingenious circuit design and low cost, and has good application prospect.
The foregoing has outlined and described the basic principles, features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (3)
1. A bandpass filter with wideband high out-of-band rejection, characterized by: comprises a third-order high-pass filter, a third-order low-pass filter, a first high-frequency low-pass filter and a second high-frequency low-pass filter, wherein the third-order high-pass filter is connected with the third-order low-pass filter through the first high-frequency low-pass filter, the third-order low-pass filter is connected with the second high-frequency low-pass filter,
the initial frequency of the third-order high-pass filter is 110MHz, and the cut-off frequency of the third-order low-pass filter is 862MHz;
the third-order high-pass filter comprises a first capacitor C1, a second capacitor C2 and a third capacitor C3 which are connected in series, wherein the anode of the first capacitor C1 is connected with the anode of the next capacitor, the anode of the first capacitor C1 is connected with the anode of a fourth capacitor C4, the anode of the fourth capacitor C4 is connected with the ground through a first inductor L1, the anode of the second capacitor C2 is connected with the anode of a fifth capacitor C5, the anode of the fifth capacitor C5 is connected with the ground through a second inductor L2, the anode of the third capacitor C3 is directly connected with the ground through a third inductor L3, the anode of the first capacitor C1 is used as the input end of the third-order high-pass filter, and the anode of the third capacitor C3 is used as the output end of the third-order filter to be connected with the input end of the first high-frequency low-pass filter;
the first high-frequency low-pass filter comprises a fourth inductor L4 and a sixth capacitor C6, one end of the fourth inductor L4 is used as an input end of the first high-frequency low-pass filter to be connected with the third-order high-pass filter, the other end of the fourth inductor L4 is used as an output end of the first high-frequency low-pass filter to be connected with the input end of the third-order low-pass filter, the other end of the fourth inductor L4 is also connected with the negative electrode of the sixth capacitor C6, and the positive electrode of the sixth capacitor C6 is connected with the ground;
the third-order low-pass filter comprises a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9 which are connected in series, wherein the anode of the last capacitor is connected with the anode of the next capacitor, the two poles of the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 are respectively connected with a fifth inductor L5, a sixth inductor L6 and a seventh inductor L7 in parallel, the anodes of the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 are respectively connected with the anodes of a tenth capacitor C10, an eleventh capacitor C11 and a twelfth capacitor C12, the anodes of the tenth capacitor C10, the eleventh capacitor C11 and the twelfth capacitor C12 are all connected with the ground, the anode of the seventh capacitor C7 is used as the input end of the third-order low-pass filter to be connected with the first high-frequency low-pass filter, and the anode of the ninth capacitor C9 is used as the output end of the third-order low-pass filter to be connected with the input end of the second high-frequency low-pass filter;
the second high-frequency low-pass filter comprises an eighth inductor L8 and a thirteenth capacitor C13, one end of the eighth inductor L8 is used as an input end of the second high-frequency low-pass filter to be connected with the third-order low-pass filter, the other end of the fourth inductor L4 is used as an output end of the second high-frequency low-pass filter, the other end of the eighth inductor L8 is also connected with a negative electrode of the thirteenth capacitor C13, and an anode of the thirteenth capacitor C13 is connected with the ground.
2. A wideband high out-of-band rejection bandpass filter as in claim 1 wherein: the third-order high-pass filter and the third-order low-pass filter both adopt resonance absorption structures.
3. A wideband high out-of-band rejection bandpass filter as in claim 1 wherein: the inductors in the third-order high-pass filter, the third-order low-pass filter, the first high-frequency low-pass filter and the second high-frequency low-pass filter can be hollow wire wound inductors, patch high-frequency wire wound inductors or patch high-frequency ceramic inductors.
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| CN206908757U (en) * | 2017-06-27 | 2018-01-19 | 深圳Tcl新技术有限公司 | The anti-jamming circuit and digital television of digital television |
| US11627282B2 (en) * | 2019-04-03 | 2023-04-11 | Ppc Broadband, Inc. | Passive entry adapter system for a CATV network |
| CN114928344B (en) * | 2022-06-14 | 2023-06-30 | 江南大学 | Band-pass power divider module based on IPD |
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| CN201163800Y (en) * | 2008-02-01 | 2008-12-10 | 深圳市同洲电子股份有限公司 | High-frequency signal transmission apparatus and set-top box |
| CN104506155A (en) * | 2015-01-12 | 2015-04-08 | 深圳顺络电子股份有限公司 | Filter |
| CN204885381U (en) * | 2015-07-30 | 2015-12-16 | 成都九洲迪飞科技有限责任公司 | Ultra wide band LC wave filter |
| CN204991910U (en) * | 2015-09-14 | 2016-01-20 | 成都创新达微波电子有限公司 | Absorption ripples band pass filter that declines |
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