CN114421912A - Seven-order band-pass filter circuit of transponder transmission module - Google Patents
Seven-order band-pass filter circuit of transponder transmission module Download PDFInfo
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Abstract
The invention is suitable for the related field of communication, and provides a seven-order band-pass filter circuit of a transponder transmission module, wherein the filter circuit comprises a first-order branch, a second-order branch, a third-order branch, a fourth-order branch, a fifth-order branch, a sixth-order branch and a seven-order branch, and the first-order branch to the seven-order branch in the filter circuit are sequentially connected in series. Compared with the traditional filter circuit, the band-pass filter circuit provided by the invention has the advantages that the passband is 3.8 MHz-4.7 MHz, the passband bandwidth is narrower, the stopband attenuation is less than-50 dB, and the suppression degree is better. After receiving signals, the filter circuit is used for filtering out interference signals except 3.8 MHz-4.7 MHz, the narrower passband bandwidth ensures that the more interference signals are filtered, and meanwhile, the transition band is steep, so that the interference signals in the transition band can be effectively filtered, and the transponder transmission module can better demodulate FSK signals.
Description
Technical Field
The invention belongs to the field of communication correlation, and particularly relates to a seven-order band-pass filter circuit of a transponder transmission module.
Background
The transponder transmission module is one of key devices of the motor train unit vehicle-mounted device, and the vehicle-mounted transponder transmission module, the transponder antenna and the ground transponder form a point type communication system. The transponder transmission system is a safety point type information transmission system, and information is transmitted from the ground equipment to the vehicle-mounted equipment through the transponder. The transponder may transmit fixed (via a passive transponder) or variable (via an active transponder) uplink data to the in-vehicle device depending on the application requirements. When the antenna unit passes through or stops above the corresponding transponder, an information transmission channel between the transponder and the vehicle-mounted equipment is formed. The transponder transmission system consists of ground equipment and vehicle-mounted equipment, wherein the ground equipment comprises an active transponder, a passive transponder and a ground electronic unit; the vehicle-mounted device comprises an antenna unit and a transponder transmission module. The transponder transmission system has the working principle that the transponder transmission module antenna continuously sends electromagnetic energy downwards in the running process of a train, when the ground transponder passes through the ground transponder, the ground transponder receives the electromagnetic energy and sends electromagnetic signals to the transponder transmission module antenna, the signals are received and transmitted to the transponder transmission module host through the transponder antenna, and the transponder transmission module host processes information received from the transponder antenna.
The transponder transmission module is used for processing data of the ground transponder, decoding and restoring the transponder message and transmitting the transponder message to the train control vehicle-mounted computer. The transponder transmission module is also used for receiving, filtering, digitally demodulating and processing the ground transponder information and transmitting related data. The central frequency of the uplink signal of the transponder transmission module device is 4.234MHz +/-175 KHz, the frequency deviation is +/-282 KHz, and a filter circuit is needed to filter an interference signal so as to demodulate an FSK signal better, avoid the normal operation of interference equipment and form hidden danger to the operation safety of a train.
The existing filter circuit has the advantages of smooth transition band, wide passband bandwidth, low stopband rejection and large insertion loss. Interference signals cannot be effectively filtered, and adverse effects are generated on FSK signal demodulation of the transponder transmission module.
Disclosure of Invention
In order to solve the above problems, on one hand, the invention discloses a seven-order bandpass filter circuit of a transponder transmission module, wherein the filter circuit comprises a first-order branch, a second-order branch, a third-order branch, a fourth-order branch, a fifth-order branch, a sixth-order branch and a seven-order branch, and the first-order branch to the seven-order branch in the filter circuit are sequentially connected in series;
the first order branch road is used for filtering and screens out the signal of within the specified range, the second order branch road is used for increasing filter circuit's passband flatness, the third order branch road is used for increasing filter circuit's stopband rejection degree, the fourth order branch road is used for increasing the transition zone steepness, fifth order branch road, sixth order branch road and seventh order branch road are used for further increasing filter circuit's stopband rejection degree.
Further, the first-order branch circuit comprises a first-order capacitor bank and a first-order inductor bank which are mutually connected in series, the first-order capacitor bank comprises a plurality of capacitors, and the capacitors are connected in parallel; the first-order inductance group comprises a plurality of inductors which are connected in series.
Further, the first-order capacitor bank comprises an inductor C1 and an inductor C12 which are connected in parallel;
the first-order inductance group comprises an inductance L1, an inductance L11 and an inductance L12 which are connected in series;
one end of the first-order capacitor bank is connected with the input end, the other end of the first-order capacitor bank is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of an inductor L12 through an inductor L11, and the other end of the inductor L12 is connected with a second-order branch circuit.
Further, the second-order branch comprises a second-order first branch and a second-order second branch which are connected in parallel;
the second-order first branch circuit comprises a plurality of inductors and a second-order first capacitor bank, the inductors are connected with the second-order first capacitor bank in series, and one end of the second-order first capacitor bank is grounded;
the second-order second branch circuit comprises a plurality of inductors and a second-order second inductor group, the inductors are connected with the second-order second capacitor group in series, and one end of the second-order second capacitor group is grounded.
Further, the second-order first branch comprises an inductor L13, an inductor L2 and a second-order first capacitor bank which are connected in series, and the second-order first capacitor bank comprises a capacitor C11 and a capacitor C2 which are connected in parallel; two ends of the inductor L2 are respectively connected with one end of an inductor L13 and the other end of the second-order first capacitor bank;
the second-order second branch comprises an inductor L14, an inductor L3 and a second-order second capacitor bank which are connected in series, and the second-order second capacitor bank comprises a capacitor C3 and a capacitor C13 which are connected in parallel; two ends of the inductor L3 are respectively connected with one end of the inductor L14 and the other end of the second-order second capacitor bank;
the other end of the inductor L13 is connected to the other end of the inductor L14, where the other end is connected to the first-order branch and the third-order branch.
Further, the third-order branch circuit comprises a third-order capacitor bank and a third-order inductor bank which are mutually connected in series, and the third-order capacitor bank comprises a plurality of capacitors connected in parallel; the third-order inductance group comprises a plurality of inductors connected in series.
Further, the third-order capacitor bank comprises an inductor C14 and an inductor C4 which are connected in parallel; the third-order inductance group comprises an inductance L4 and an inductance L15 which are connected in series; one end of the third-order capacitor bank is connected with the second-order branch circuit, the other end of the third-order capacitor bank is connected with one end of an inductor L4, the other end of an inductor L4 is connected with one end of an inductor L15, and the other end of an inductor L15 is connected with the fourth-order branch circuit.
Further, the fourth-order branch comprises a fourth-order first branch and a fourth-order second branch which are connected in parallel;
the four-order first branch circuit comprises a plurality of inductors and a four-order first capacitor group, the inductors are connected with the four-order first capacitor group in series, and one end of the four-order first capacitor group is grounded;
the fourth-order second branch circuit comprises a plurality of inductors and a fourth-order second inductor group, the inductors are connected with the fourth-order second capacitor group in series, and one end of the fourth-order second capacitor group is grounded.
Further, the fourth-order first branch comprises an inductor L17, an inductor L6, an inductor L5 and a fourth-order first capacitor bank which are sequentially connected in series, wherein the fourth-order first capacitor bank comprises a capacitor C15 and a capacitor C5 which are connected in parallel; two ends of the inductor L5 are respectively connected with one end of an inductor L16 and the other end of the fourth-order first capacitor bank; the other end of the inductor L16 is connected with one end of an inductor L17;
the fourth-order second branch comprises an inductor L18, an inductor L6 and a fourth-order second capacitor bank which are connected in series, and the fourth-order second capacitor bank comprises a capacitor C6 and a capacitor C16 which are connected in parallel; two ends of the inductor L6 are respectively connected with one end of an inductor L18 and the other end of the fourth-order second capacitor bank;
the other end of the inductor L17 is connected to the other end of the inductor L18, and the connection point is further connected to the third-order branch and the fifth-order branch.
Furthermore, the five-order branch comprises a five-order capacitor bank and a five-order inductor bank which are mutually connected in series, and the five-order capacitor bank comprises a plurality of capacitors connected in parallel; the five-step inductance group comprises a plurality of series-connected inductors.
Further, the fifth-order capacitor bank comprises an inductor C7 and an inductor C17 which are connected in parallel; the five-stage inductance group comprises an inductance L7 and an inductance L19 which are connected in series; one end of the five-order capacitor bank is connected with the four-order branch circuit, the other end of the five-order capacitor bank is connected with one end of an inductor L7, the other end of an inductor L7 is connected with one end of an inductor L19, and the other end of an inductor L19 is connected with the six-order branch circuit.
Further, the sixth-order branch comprises a sixth-order first branch and a sixth-order second branch which are connected in parallel;
the six-order first branch circuit comprises a plurality of inductors and a six-order first capacitor bank, the inductors are connected with the six-order first capacitor bank in series, and one end of the six-order first capacitor bank is grounded;
the six-order second branch circuit comprises a plurality of inductors and a six-order second inductor group, the inductors are connected with the six-order second capacitor group in series, and one end of the six-order second capacitor group is grounded.
Further, the sixth-order first branch comprises an inductor L20, an inductor L8 and a sixth-order first capacitor bank which are connected in series with each other, wherein the sixth-order first capacitor bank comprises a capacitor C18 and a capacitor C8 which are connected in parallel with each other; two ends of the inductor L8 are respectively connected with one end of the inductor L20 and the other end of the sixth-order first capacitor bank;
the sixth-order second branch comprises an inductor L21, an inductor L9 and a sixth-order second capacitor bank which are connected in series, and the sixth-order second capacitor bank comprises a capacitor C9 and a capacitor C19 which are connected in parallel; two ends of the inductor L9 are respectively connected with one end of the inductor L21 and the other end of the sixth-order second capacitor bank;
the other end of the inductor L20 is connected to the other end of the inductor L21, and the fifth-order branch and the seventh-order branch are connected to the other end of the inductor L20.
Furthermore, the seven-order branch comprises a seven-order capacitor bank and a seven-order inductor bank which are mutually connected in series, and the seven-order capacitor bank comprises a plurality of capacitors connected in parallel; the seven-order inductance group comprises a plurality of inductors connected in series.
Further, the seven-order capacitor bank comprises an inductor C20 and an inductor C10 which are connected in parallel; the seven-stage inductance group comprises an inductance L10 and an inductance L22 which are connected in series; one end of the seven-order capacitor bank is connected with the six-order branch circuit, the other end of the seven-order capacitor bank is connected with one end of an inductor L10, the other end of an inductor L10 is connected with one end of an inductor L22, and the other end of an inductor L22 is connected with an output end.
Compared with the prior art, the invention has the following beneficial effects:
compared with the traditional filter circuit, the band-pass filter circuit provided by the invention has the advantages that the passband is 3.8 MHz-4.7 MHz, the passband bandwidth is narrower, the stopband attenuation is less than-50 dB, and the suppression degree is better. After receiving signals, the filter circuit is used for filtering out interference signals except 3.8 MHz-4.7 MHz, the narrower passband bandwidth ensures that the more interference signals are filtered, and meanwhile, the transition band is steep, so that the interference signals in the transition band can be effectively filtered, and the transponder transmission module can better demodulate FSK signals.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 shows a schematic diagram of a seven-order bandpass filter circuit according to an embodiment of the invention;
fig. 2 shows circuit division diagrams of respective stages of a seven-stage bandpass filter circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to solve the technical problems of the background and designs a seven-order band-pass filter circuit, which comprises a first-order branch, a second-order branch, a third-order branch, a fourth-order branch, a fifth-order branch, a sixth-order branch and a seventh-order branch, wherein the first-order branch to the seventh-order branch in the filter circuit are sequentially connected in series;
the first order branch road is used for filtering and screens out the signal of within the specified range, the second order branch road is used for increasing filter circuit's passband flatness, the third order branch road is used for increasing filter circuit's stopband rejection degree, the fourth order branch road is used for increasing the transition zone steepness, fifth order branch road, sixth order branch road and seventh order branch road are used for further increasing filter circuit's stopband rejection degree.
Compared with the original filter circuit, the band-pass filter circuit has the advantages that the passband of the band-pass filter circuit is 3.8 MHz-4.7 MHz, the passband bandwidth is narrower, the stopband attenuation is less than-50 dB, and the good suppression degree is realized. After receiving signals, the filter circuit is used for filtering out interference signals except 3.8 MHz-4.7 MHz, the narrower passband bandwidth ensures that the more interference signals are filtered, and meanwhile, the transition band is steep, so that the interference signals in the transition band can be effectively filtered, and the transponder transmission module can better demodulate FSK signals.
In an embodiment of the present invention, as shown in fig. 1 and fig. 2, the first-order branch includes a first-order capacitor bank and a first-order inductor bank connected in series with each other, the first-order capacitor bank includes a plurality of capacitors, and the plurality of capacitors are connected in parallel; the first-order inductance group comprises a plurality of inductors which are connected in series.
In one case of the present embodiment, the first-order capacitor bank includes an inductor C1 and an inductor C12 connected in parallel; the first-order inductance group comprises an inductance L1, an inductance L11 and an inductance L12 which are connected in series; one end of the first-order capacitor bank is connected with the input end, the other end of the first-order capacitor bank is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of an inductor L12 through an inductor L11, and the other end of the inductor L12 is connected with a second-order branch circuit.
In the above embodiment, the components in the first-order branch are exemplarily selected, the capacitance of the capacitor C1 is 43pF, the capacitance of the capacitor C12 is 220pF, the inductance of the inductor L1 is 3.3 μ H, the inductance of the inductor L11 is 1 μ H, and the inductance of the inductor 12 is 1 μ H. The capacitors in the first-order branch are connected in parallel and the inductors are connected in series to interact, a single pass band with the central frequency point of 4.263MHz is formed, the BTM antenna receives signals, signals near 4.234MHz are filtered out approximately through the first-order branch, the stop band rejection degree is weak, and the filtering effect is poor.
In an embodiment of the present invention, as shown in fig. 1 and fig. 2, the second-order branch includes a second-order first branch and a second-order second branch connected in parallel with each other;
the second-order first branch circuit comprises a plurality of inductors and a second-order first capacitor bank, the inductors are connected with the second-order first capacitor bank in series, and one end of the second-order first capacitor bank is grounded;
the second-order second branch circuit comprises a plurality of inductors and a second-order second inductor group, the inductors are connected with the second-order second capacitor group in series, and one end of the second-order second capacitor group is grounded.
In one case of this embodiment, the second-order first branch includes an inductor L13, an inductor L2, and a second-order first capacitor bank connected in series with each other, and the second-order first capacitor bank includes a capacitor C11 and a capacitor C2 connected in parallel with each other; two ends of the inductor L2 are respectively connected with one end of an inductor L13 and the other end of the second-order first capacitor bank;
the second-order second branch comprises an inductor L14, an inductor L3 and a second-order second capacitor bank which are connected in series, and the second-order second capacitor bank comprises a capacitor C3 and a capacitor C13 which are connected in parallel; two ends of the inductor L3 are respectively connected with one end of the inductor L14 and the other end of the second-order second capacitor bank;
the other end of the inductor L13 is connected to the other end of the inductor L14, where the other end is connected to the first-order branch and the third-order branch.
In the above embodiment, the second-order branch is exemplarily patterned, the inductance of the inductor L13 is 10 μ H, the inductance of the inductor L2 is 1 μ H, the capacitance of the capacitor C11 is 100pF, the capacitance of the capacitor C2 is 75pF, the inductance of the inductor L14 is 6.8H, the inductance of the inductor L3 is 1.2 μ H, the capacitance of the capacitor C3 is 120pF, and the capacitance of the capacitor C13 is 7.5 pF. The inductor and the capacitor in the second-order branch circuit are in series-parallel interaction, so that the pass band flatness of the second-order filter circuit is increased, the transition band variation amplitude is increased, and the attenuation of correct signals can be reduced when the signals pass through the second-order branch circuit.
In an embodiment of the present invention, as shown in fig. 1 and fig. 2, the third-order branch includes a third-order capacitor bank and a third-order inductor bank connected in series with each other, and the third-order capacitor bank includes a plurality of capacitors connected in parallel; the third-order inductance group comprises a plurality of inductors connected in series.
In one case of the present embodiment, the third-order capacitor bank includes an inductor C14 and an inductor C4 connected in parallel; the third-order inductance group comprises an inductance L4 and an inductance L15 which are connected in series; one end of the third-order capacitor bank is connected with the second-order branch circuit, the other end of the third-order capacitor bank is connected with one end of an inductor L4, the other end of an inductor L4 is connected with one end of an inductor L15, and the other end of an inductor L15 is connected with the fourth-order branch circuit.
In the above embodiment, the components in the third-order branch are exemplarily selected, the capacitance of the capacitor C14 is 120pF, the capacitance of the capacitor C4 is 15pF, the inductance of the inductor L4 is 10 μ H, and the inductance of the inductor L15 is 330 nH. The capacitor parallel connection and the inductor series connection combined action in the three-order branch circuit enable the stop band suppression degree of the filter circuit to be increased, and interference signals can be effectively filtered when the signals pass through the three-order branch circuit.
In an embodiment of the present invention, as shown in fig. 1 and 2, the fourth-order branch includes a fourth-order first branch and a fourth-order second branch connected in parallel with each other;
the four-order first branch circuit comprises a plurality of inductors and a four-order first capacitor group, the inductors are connected with the four-order first capacitor group in series, and one end of the four-order first capacitor group is grounded;
the fourth-order second branch circuit comprises a plurality of inductors and a fourth-order second inductor group, the inductors are connected with the fourth-order second capacitor group in series, and one end of the fourth-order second capacitor group is grounded.
In one case of the embodiment, the fourth-order first branch comprises an inductor L17, an inductor L6, an inductor L5 and a fourth-order first capacitor bank which are sequentially connected in series, and the fourth-order first capacitor bank comprises a capacitor C15 and a capacitor C5 which are connected in parallel; two ends of the inductor L5 are respectively connected with one end of an inductor L16 and the other end of the fourth-order first capacitor bank; the other end of the inductor L16 is connected with one end of an inductor L17;
the fourth-order second branch comprises an inductor L18, an inductor L6 and a fourth-order second capacitor bank which are connected in series, and the fourth-order second capacitor bank comprises a capacitor C6 and a capacitor C16 which are connected in parallel; two ends of the inductor L6 are respectively connected with one end of an inductor L18 and the other end of the fourth-order second capacitor bank;
the other end of the inductor L17 is connected to the other end of the inductor L18, and the connection point is further connected to the third-order branch and the fifth-order branch.
In the above embodiment, the inductance of the inductor L17 is 10 μ H, the inductance of the inductor L16 is 2.2 μ H, the inductance of the inductor L5 is 2.2 μ H, the capacitance of the capacitor C15 is 120pF, the capacitance of the capacitor C5 is 8pF, the inductance of the inductor L18 is 10 μ H, the inductance of the inductor L6 is 1 μ H, the capacitance of the capacitor C6 is 91pF, and the capacitance of the capacitor C16 is 6.2 pF. The capacitors in the fourth-order branch are connected in parallel and the inductors are connected in series to jointly act, so that the stop band suppression degree of the filter circuit is increased, and interference signals can be effectively filtered when the signals pass through the fourth-order branch. Meanwhile, the fourth-order branch increases the steepness of the transition band, and better filters interference signals in the frequency range of the transition band.
In an embodiment of the present invention, as shown in fig. 1 and fig. 2, the five-step branch includes a five-step capacitor bank and a five-step inductor bank connected in series with each other, and the five-step capacitor bank includes a plurality of capacitors connected in parallel; the five-step inductance group comprises a plurality of series-connected inductors.
In one case of the present embodiment, the five-step capacitor bank includes an inductor C7 and an inductor C17 connected in parallel; the five-stage inductance group comprises an inductance L7 and an inductance L19 which are connected in series; one end of the five-order capacitor bank is connected with the four-order branch circuit, the other end of the five-order capacitor bank is connected with one end of an inductor L7, the other end of an inductor L7 is connected with one end of an inductor L19, and the other end of an inductor L19 is connected with the six-order branch circuit.
In the above embodiment, the components in the five-step branch are exemplarily selected, the capacitance of the capacitor C17 is 51pF, the capacitance of the capacitor C7 is 68pF, the inductance of the inductor L7 is 10 μ H, and the inductance of the inductor L19 is 1.8 μ H. The capacitors in the five-order branch circuit are connected in parallel with each other and then connected in series with the inductor in the circuit, so that the stop band rejection degree is increased, and interference signals in signals passing through the five-order branch circuit can be filtered more cleanly than interference signals in signals passing through the four-order branch circuit.
In an embodiment of the present invention, as shown in fig. 1 and 2, the sixth-order branch includes a sixth-order first branch and a sixth-order second branch connected in parallel with each other;
the six-order first branch circuit comprises a plurality of inductors and a six-order first capacitor bank, the inductors are connected with the six-order first capacitor bank in series, and one end of the six-order first capacitor bank is grounded;
the six-order second branch circuit comprises a plurality of inductors and a six-order second inductor group, the inductors are connected with the six-order second capacitor group in series, and one end of the six-order second capacitor group is grounded.
In one case of the embodiment, the sixth-order first branch comprises an inductor L20, an inductor L8 and a sixth-order first capacitor bank connected in series with each other, and the sixth-order first capacitor bank comprises a capacitor C18 and a capacitor C8 connected in parallel with each other; two ends of the inductor L8 are respectively connected with one end of the inductor L20 and the other end of the sixth-order first capacitor bank;
the sixth-order second branch comprises an inductor L21, an inductor L9 and a sixth-order second capacitor bank which are connected in series, and the sixth-order second capacitor bank comprises a capacitor C9 and a capacitor C19 which are connected in parallel; two ends of the inductor L9 are respectively connected with one end of the inductor L21 and the other end of the sixth-order second capacitor bank;
the other end of the inductor L20 is connected to the other end of the inductor L21, and the fifth-order branch and the seventh-order branch are connected to the other end of the inductor L20.
In the above embodiment, the components in the sixth-order branch are exemplarily selected, the inductance of the inductor L20 is 1.5 μ H, the inductance of the inductor L8 is 1.8 μ H, the capacitance of the capacitor C18 is 680pF, the capacitance of the capacitor C8 is 22pF, the inductance of the inductor L21 is 1 μ H, the inductance of the inductor L9 is 1 μ H, the capacitance of the capacitor C9 is 200pF, and the capacitance of the capacitor C19 is 220 pF. The six-order branch circuit and the five-order branch circuit have similar functions, the six-order branch circuit is added on the original basis to improve the attenuation degree of the stop band, capacitors in the six-order branch circuit are connected in parallel with each other and then connected in series with inductors in the circuit, so that the inhibition degree of the stop band is increased, and interference signals in signals passing through the six-order branch circuit can be filtered out more cleanly compared with the signals of the five-order branch circuit.
In an embodiment of the present invention, as shown in fig. 1 and fig. 2, the seven-stage branch includes a seven-stage capacitor bank and a seven-stage inductor bank connected in series, where the seven-stage capacitor bank includes a plurality of capacitors connected in parallel; the seven-order inductance group comprises a plurality of inductors connected in series.
In one case of the present embodiment, the seven-stage capacitor bank includes an inductor C20 and an inductor C10 connected in parallel; the seven-stage inductance group comprises an inductance L10 and an inductance L22 which are connected in series; one end of the seven-order capacitor bank is connected with the six-order branch circuit, the other end of the seven-order capacitor bank is connected with one end of an inductor L10, the other end of an inductor L10 is connected with one end of an inductor L22, and the other end of an inductor L22 is connected with an output end.
In the above embodiment, the components in the seven-stage branch are exemplarily selected, the capacitance of the capacitor C20 is 180pF, the capacitance of the capacitor C10 is 3pF, the inductance of the inductor L10 is 6.8 μ H, and the inductance of the inductor L22 is 820 nH. The seven-order branch can increase the stop band rejection degree, the passband can be ensured to be narrower, and the effect is more obvious when the signals pass through the seven-order branch and can filter out interference signals in a larger range. The effect is generated by the mutual effect of the capacitors in the seven-order branch circuit in parallel connection and the inductors in series connection.
The seven-order band-pass filter circuit of the invention enables the output signal to be basically filtered relative to the input signal except the signal in the pass band range. The steepness of the transition zone is better, and interference signals in the range of the transition zone can be effectively filtered. The filter circuit can be used for a transponder transmission module, and can filter interference components of uplink signals of the transponder transmission module, so that the transponder transmission module can better demodulate FSK signals.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (15)
1. A seven-order band-pass filter circuit of a transponder transmission module is characterized in that the filter circuit comprises a first-order branch, a second-order branch, a third-order branch, a fourth-order branch, a fifth-order branch, a sixth-order branch and a seventh-order branch, wherein the first-order branch to the seventh-order branch in the filter circuit are sequentially connected in series;
the first order branch road is used for filtering and screens out the signal of within the specified range, the second order branch road is used for increasing filter circuit's passband flatness, the third order branch road is used for increasing filter circuit's stopband rejection degree, the fourth order branch road is used for increasing the transition zone steepness, fifth order branch road, sixth order branch road and seventh order branch road are used for further increasing filter circuit's stopband rejection degree.
2. The seven-order bandpass filter circuit of claim 1 wherein the first-order branch comprises a first-order capacitor bank and a first-order inductor bank connected in series with each other, the first-order capacitor bank comprising a plurality of capacitors connected in parallel; the first-order inductance group comprises a plurality of inductors which are connected in series.
3. The transponder transmission module seventh order bandpass filter circuit of claim 2 wherein the first order capacitor bank comprises an inductor C1 and an inductor C12 connected in parallel;
the first-order inductance group comprises an inductance L1, an inductance L11 and an inductance L12 which are connected in series;
one end of the first-order capacitor bank is connected with the input end, the other end of the first-order capacitor bank is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of an inductor L12 through an inductor L11, and the other end of the inductor L12 is connected with a second-order branch circuit.
4. The seven-order bandpass filter circuit of claim 1 wherein the second-order branch comprises a second-order first branch and a second-order second branch connected in parallel with each other;
the second-order first branch circuit comprises a plurality of inductors and a second-order first capacitor bank, the inductors are connected with the second-order first capacitor bank in series, and one end of the second-order first capacitor bank is grounded;
the second-order second branch circuit comprises a plurality of inductors and a second-order second inductor group, the inductors are connected with the second-order second capacitor group in series, and one end of the second-order second capacitor group is grounded.
5. The transponder transmission module seventh order bandpass filter circuit according to claim 4, characterized in that the second order first branch comprises an inductance L13, an inductance L2 and a second order first capacitor bank connected in series with each other, the second order first capacitor bank comprising a capacitor C11 and a capacitor C2 connected in parallel with each other; two ends of the inductor L2 are respectively connected with one end of an inductor L13 and the other end of the second-order first capacitor bank;
the second-order second branch comprises an inductor L14, an inductor L3 and a second-order second capacitor bank which are connected in series, and the second-order second capacitor bank comprises a capacitor C3 and a capacitor C13 which are connected in parallel; two ends of the inductor L3 are respectively connected with one end of the inductor L14 and the other end of the second-order second capacitor bank;
the other end of the inductor L13 is connected to the other end of the inductor L14, where the other end is connected to the first-order branch and the third-order branch.
6. The seven-order bandpass filter circuit of claim 1 wherein the third-order branch comprises a third-order capacitor bank and a third-order inductor bank connected in series with each other, the third-order capacitor bank comprising a plurality of capacitors connected in parallel; the third-order inductance group comprises a plurality of inductors connected in series.
7. The transponder transmission module seven-order bandpass filter circuit of claim 6 wherein the three-order capacitor bank includes an inductor C14 and an inductor C4 connected in parallel; the third-order inductance group comprises an inductance L4 and an inductance L15 which are connected in series; one end of the third-order capacitor bank is connected with the second-order branch circuit, the other end of the third-order capacitor bank is connected with one end of an inductor L4, the other end of an inductor L4 is connected with one end of an inductor L15, and the other end of an inductor L15 is connected with the fourth-order branch circuit.
8. The transponder transmission module seventh order bandpass filter circuit of claim 1, characterized in that the fourth order branch comprises a fourth order first branch and a fourth order second branch connected in parallel with each other;
the four-order first branch circuit comprises a plurality of inductors and a four-order first capacitor group, the inductors are connected with the four-order first capacitor group in series, and one end of the four-order first capacitor group is grounded;
the fourth-order second branch circuit comprises a plurality of inductors and a fourth-order second inductor group, the inductors are connected with the fourth-order second capacitor group in series, and one end of the fourth-order second capacitor group is grounded.
9. The seven-order bandpass filter circuit of claim 8 wherein the fourth-order first branch comprises an inductor L17, an inductor L6, an inductor L5, and a fourth-order first capacitor bank connected in series in that order, the fourth-order first capacitor bank comprising a capacitor C15 and a capacitor C5 connected in parallel with each other; two ends of the inductor L5 are respectively connected with one end of an inductor L16 and the other end of the fourth-order first capacitor bank; the other end of the inductor L16 is connected with one end of an inductor L17;
the fourth-order second branch comprises an inductor L18, an inductor L6 and a fourth-order second capacitor bank which are connected in series, and the fourth-order second capacitor bank comprises a capacitor C6 and a capacitor C16 which are connected in parallel; two ends of the inductor L6 are respectively connected with one end of an inductor L18 and the other end of the fourth-order second capacitor bank;
the other end of the inductor L17 is connected to the other end of the inductor L18, and the connection point is further connected to the third-order branch and the fifth-order branch.
10. The seven-order bandpass filter circuit of claim 1 wherein the five-order branch comprises a five-order capacitor bank and a five-order inductor bank connected in series with each other, the five-order capacitor bank comprising a plurality of capacitors connected in parallel; the five-step inductance group comprises a plurality of series-connected inductors.
11. The transponder transmission module seventh order bandpass filter circuit of claim 10 wherein the fifth order capacitor bank comprises an inductor C7 and an inductor C17 connected in parallel; the five-stage inductance group comprises an inductance L7 and an inductance L19 which are connected in series; one end of the five-order capacitor bank is connected with the four-order branch circuit, the other end of the five-order capacitor bank is connected with one end of an inductor L7, the other end of an inductor L7 is connected with one end of an inductor L19, and the other end of an inductor L19 is connected with the six-order branch circuit.
12. The transponder transmission module seventh-order bandpass filter circuit according to claim 1, characterized in that the sixth-order branch comprises a sixth-order first branch and a sixth-order second branch connected in parallel with each other;
the six-order first branch circuit comprises a plurality of inductors and a six-order first capacitor bank, the inductors are connected with the six-order first capacitor bank in series, and one end of the six-order first capacitor bank is grounded;
the six-order second branch circuit comprises a plurality of inductors and a six-order second inductor group, the inductors are connected with the six-order second capacitor group in series, and one end of the six-order second capacitor group is grounded.
13. The transponder transmission module seventh-order bandpass filter circuit according to claim 12, characterized in that the sixth-order first branch comprises an inductance L20, an inductance L8 and a sixth-order first capacitor bank connected in series with each other, the sixth-order first capacitor bank comprising a capacitor C18 and a capacitor C8 connected in parallel with each other; two ends of the inductor L8 are respectively connected with one end of the inductor L20 and the other end of the sixth-order first capacitor bank;
the sixth-order second branch comprises an inductor L21, an inductor L9 and a sixth-order second capacitor bank which are connected in series, and the sixth-order second capacitor bank comprises a capacitor C9 and a capacitor C19 which are connected in parallel; two ends of the inductor L9 are respectively connected with one end of the inductor L21 and the other end of the sixth-order second capacitor bank;
the other end of the inductor L20 is connected to the other end of the inductor L21, and the fifth-order branch and the seventh-order branch are connected to the other end of the inductor L20.
14. The transponder transmission module seven-order bandpass filter circuit of any one of claims 1-13 wherein the seven-order branch comprises a seven-order capacitor bank and a seven-order inductor bank connected in series with each other, the seven-order capacitor bank comprising a plurality of capacitors connected in parallel; the seven-order inductance group comprises a plurality of inductors connected in series.
15. The transponder transmission module seventh order bandpass filter circuit of claim 14 wherein the seventh order capacitor bank comprises an inductor C20 and an inductor C10 connected in parallel; the seven-stage inductance group comprises an inductance L10 and an inductance L22 which are connected in series; one end of the seven-order capacitor bank is connected with the six-order branch circuit, the other end of the seven-order capacitor bank is connected with one end of an inductor L10, the other end of an inductor L10 is connected with one end of an inductor L22, and the other end of an inductor L22 is connected with an output end.
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| CN114421912B (en) | 2022-07-05 |
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