CN110174592A - A kind of multistage syntype decomposes barron structure and cable characteristic test termination circuit - Google Patents

Abstract

The invention relates to a multi-stage full-mode decomposition balun structure and a cable characteristic test termination circuit constructed based on the structure. The multi-level full-mode decomposition balun structure is based on the parallel and cascaded construction of the common-differential mode decomposition unit (CDU), which can connect cables composed of multiple wire pairs, decompose and retain all its modes and output; on this basis, add The automatic gating structure can construct the cable characteristic test terminal circuit, and realize the connection between each mode output and the instrument port is selected and controlled by the digital level.

Description

A multi-level full-mode decomposition balun structure and cable characteristic test termination circuit

technical field

The invention relates to a multi-stage full-mode decomposition balun structure and a cable characteristic test termination circuit based on the structure.

Background technique

The propagation characteristics of electromagnetic waves in cables can be decomposed into different modes for characterization. The ones that have been seen in the reports are symmetrical parallel pairs or twisted pairs, which can be decomposed into two modes, namely common mode and differential mode [1] [2]; and for multi-conductor lines, the mode can also be Decomposition, the number of modes is determined by the number of conductors [2]; taking a cable bundle composed of two pairs of twisted pairs as an example, it can be decomposed into four modes [3]. When cables are connected to cables or cables are connected to other terminal structures (such as antennas, circuit boards, etc.), if the balance states on both sides are different, coupling between different modes will occur, resulting in performance degradation. At this time, it must be connected through a balanced-unbalanced conversion structure (ie, a balun structure) [4].

The traditional balun structure is mostly used for coaxial line-dipole antenna termination and circuit board differential-single-ended conversion. Its design purpose is to correctly connect the differential mode of the double-conductor structure on both sides, and at the same time suppress the common mode. to ensure that the system works properly. For cables composed of multiple pairs, only the traditional balun structure can be terminated for each pair separately, so as to preserve the differential mode signal of each pair, while suppressing and eliminating other modes will result in half of the Pattern information loss. Taking the cable composed of four pairs of twisted pairs as an example, there are eight of them in all modes, while the traditional balun can only keep four. However, in fields involving multi-conductor cable testing and multi-mode signal transmission, other mode signals are equally important and must be separated and retained, which is difficult for traditional baluns to apply.

Therefore, the present invention designs a multi-level full-mode decomposition balun structure. For a cable system composed of multiple wire pairs, it can provide simultaneous access to multiple wire ends, and decompose and retain all the transmission modes it contains. It also provides output ports respectively, and has application value in the fields of cable characteristic test and analysis, multi-mode communication, etc.

In order to realize the automatic measurement of multi-pair cables, an automatic gating structure is added on the basis of the multi-level full-mode decomposition balun structure of the present invention, and a cable characteristic test termination circuit is designed, which can realize the connection between the output ports of each mode and The CNC automatic gating function of the instrument port provides a hardware foundation for the development of an automated test system and improves test efficiency. Since there is less attention paid to the multi-mode measurement of multi-pair cables in the industry, no similar circuit design has been reported.

[1] Clayton R. Paul. Introduction to Electromagnetic Compatibility (Second Edition) [M]. Translated by Wen Yinghong et al. Beijing: People's Posts and Telecommunications Press, 2007.9: 253-278.

[2] Clayton R.Paul. Analysis of Multiconductor Transmission Lines (Second Edition) [M]. Translated by Yang Xiaoxian, Zheng Tao. Beijing: China Electric Power Press, 2013.2.

[3] J.Wang, X.Song, D.Su and B.Li. Near-Field Radiation Calculation of Irregular Wiring Twisted-Wire Pairs Based on Mode Decomposition[J].IEEE Transactions on Electromagnetic Compatibility,2017,59(2): 600-608.

[4] John D.Kraus, Ronald J.Marhefka. Antenna (Third Edition) (Volume 2) [M]. Translated by Zhang Wenxun. Beijing: Electronic Industry Press, 2018.1:248-262.

Contents of the invention

The technical solution of the present invention is to overcome the deficiencies of the prior art and provide a multi-level full-mode decomposition balun structure. For a cable system composed of multiple wire pairs, it can provide simultaneous access to multiple wire ends, including All the transmission modes are decomposed and reserved and output ports are provided respectively, which has application value in the fields of cable characteristic test analysis and multi-mode communication; on this basis, an automatic gating structure is added to design a cable characteristic test termination The circuit realizes the numerical control automatic gating function of each mode output port and the instrument port, provides a hardware foundation for the development of an automated test system, and improves test efficiency.

Technical solution of the present invention:

A multi-level full-mode decomposition balun structure, consisting of N common-differential mode decomposition units CDU, a cascaded CDU structure formed by cascading, and between the cascaded CDU structures; and between the cascaded CDU structure and the CDU Parallel cascade CDU structure formed by further parallel connection; N≥2, N is a positive integer.

Each CDU has 4 pins, two of which are input pins, i.e. pin 1 and pin 2, and the other two pins are respectively differential mode output pins, i.e. pin 3 and common mode output pin Pin, that is, pin 4; the CDU includes a differential mode decomposition part and a common mode decomposition part, each of which is based on a radio frequency transformer RFT, and the differential mode decomposition part and the common mode decomposition part realize input independently Differential mode signal decomposition and common mode signal decomposition functions; for the differential mode decomposition part, the two input pins of the CDU are connected to a pair of non-inverting pins of the RFT, and the other pair of non-inverting pins of the RFT are respectively grounded and differential mode output pins pin; for the common mode decomposition part, the two input pins of the CDU are connected to a pair of inverting pins of the RFT, and the other pair of inverting pins of the RFT are interconnected and then connected to the common mode output pin.

When the N is equal to 2, a 2-level cascaded CDU structure is formed, and the 2-level cascaded CDU structure is composed of 3 CDUs, and the input pins of the two CDUs are arranged in sequence to form 4 input pins of the 2-level cascaded CDU structure. Arrange the differential mode output pins of these two CDUs in turn to form the first and second output pins of the 2-level cascaded CDU structure; connect the common mode output pins of the two CDUs to the third CDU respectively Two of the two, and then the differential mode output pin and common mode output pin of the third CDU are respectively used as the third and fourth output pins of the 2-level cascaded CDU structure; through the 2-level cascading of CDUs, the composition includes 2-level cascaded CDU structure with 4 input pins and 4 output pins.

The implementation of the multi-level cascaded CDU structure when N is greater than 2 is: through the 2-level cascading of CDUs, a 2-level cascaded CDU structure comprising 4 input pins and 4 output pins is formed, which is denoted as CDU-2; 2 CDU-2 and 1 CDU constitute a circuit structure including 8 input pins and 8 output pins, which is denoted as CDU-3; similarly, for the case where N is greater than 2, 2 CDU-N and 1 CDU Form a circuit structure including 2 ^N+1 input pins and 2 ^N+1 output pins, denoted as CDU-{N+1}; CDU-{N+ is composed of 2 CDU-N and 1 CDU 1} is connected as follows: use all input pins of the first CDU-N as the first to second ^N input pins of CDU-{N+1}, and the order remains unchanged; use the second CDU- All input pins of N are used as the 2nd ^N +1 to 2nd ^N+ 1th input pins of CDU-{N+1}, the order remains unchanged; the first 2 ^N -1 of the 1st CDU-N The output pins are used as the 1st to 2nd N -1 output pins of CDU-{N+1}, and the first 2 ^N -1 output pins of the 2nd CDU- ^N are used as CDU-{N+1} The 2nd ^N to the 2nd ^N+1 -2 output pins of the first CDU-N; connect the 2nd ^N of the first CDU-N, that is, the last output pin to the pin 1 of the CDU, and the second CDU-N The 2nd ^N and last output pin of CDU is connected to pin 2 of CDU; pin 3 and pin 4 of CDU are respectively used as 2N+1-1 and 2N+1 of CDU-{N+1} output pin.

The parallel connection mode in the parallel cascaded CDU structure is as follows: number N CDUs or cascaded CDU structures from 1 to N, and sequentially sort the input pins of the 1st to Nth CDUs or cascaded CDU structures, as The input pins of the parallel cascaded CDU structure; sequentially sort the output pins of the 1st to Nth CDUs or the cascaded CDU structure, and use them as the output pins of the parallel cascaded CDU structure.

A cable characteristic test termination circuit with a multi-level full-mode decomposition balun structure, adding an automatic gating structure on the basis of the multi-level full-mode decomposition balun structure to form a complete terminal circuit; multi-level full-mode decomposition The input end of the balun structure is used as the input end of the terminal circuit and connected to the cable to be tested; the output end of the multi-level full mode decomposition balun structure is connected to the input end of the automatic gating structure; the output end of the automatic gating structure As the output terminal of the terminal circuit, it is connected to the instrument port.

The automatic gating structure is realized based on a radio frequency single-pole multi-throw switch and its combination. Pins, multiple multiple pins to be selected and multiple control pins, which can be connected to the common pin and which pin to be selected can be determined according to the level value of the control pin; multi-level full-mode decomposition of the balun structure input pin It is directly connected to the cable under test, and the output pin is connected to the multi-channel port to be selected in the automatic gating structure; the general pin of the automatic gating structure is connected to the instrument port; The signal of each mode is obtained by structure decomposition, which is input to the automatic gating structure to be selected; then the automatic gating structure decides which channel to input to the instrument for measurement according to the control level.

The advantage of the present invention compared with prior art is:

(1) The traditional balun structure can only decompose and retain the differential mode mode of each line pair, and will lose half of the mode information; while the multi-level full mode decomposition balun structure in the present invention can decompose and retain all mode information. The principle is to form a common-differential mode decomposition unit (CDU) by adding a circuit structure for extracting common mode on the basis of the traditional transformer balun, so as to realize the simultaneous retention of common-mode and differential-mode information of a single line pair; and then through the parallel or cascaded connection of the CDU Realize its ability to access multiple wire pairs at the same time.

(2) The cable characteristic test termination circuit in the present invention can realize the functions of cable full-mode decomposition, output and automatic gating with the instrument port, which cannot be realized in the prior art. The principle is that the above-mentioned multi-level full-mode decomposition balun structure and automatic gating structure are adopted.

Description of drawings

Fig. 1 is a radio frequency transformer (RFT) structure;

Fig. 2 is a common differential mode decomposition unit (CDU) structural diagram;

Figure 3 is a 2-level cascaded CDU structure (CDU-2);

Figure 4 is a 3-level cascaded CDU structure (CDU-3);

Figure 5 is a SP8T composed of 1 SPDT and 2 SP4T cascaded;

Fig. 6 is a structural block diagram of the cable characteristic test termination circuit;

Figure 7 is a schematic diagram of a typical cable characteristic test termination circuit based on CDU-3.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The multi-stage full-mode decomposition balun structure in the present invention is a cascaded CDU structure composed of two or more common-differential mode decomposition units (CDUs) through 2-level cascading or multi-level cascading forms, or by N ( N≥2, which is a positive integer) CDU or cascaded CDU in parallel to form a parallel cascaded CDU structure.

The core device required by the multi-stage full-mode decomposition balun structure of the present invention is a radio frequency transformer (RFT). The RFT is composed of two coupled inductors. Set the two ends of one inductor to pin 1 and pin 3 respectively, and the two ends of the other inductor to be pin 2 and pin 4 respectively; pin 1 and pin 2 is the non-inverting terminal, marked with a small circle, as shown in Figure 1.

First, construct the common-differential mode decomposition unit (CDU) based on RFT, and its structure is shown in Fig. 2 . The CDU has 4 pins, pin 1 and pin 2 are input pins, pin 3 is a differential mode output pin, and pin 4 is a common mode output pin. The CDU consists of a differential mode decomposition part and a common mode decomposition part, and each part is constructed based on an RFT. Connect one RFT pin 1 and pin 2 to CDU pin 1 and pin 2 respectively, RFT pin 4 to ground, and RFT pin 3 to CDU pin 3 to form a differential mode decomposition part; connect one RFT pin 3 and pin 2 are connected to CDU pin 1 and pin 2 respectively, RFT pin 1 and pin 4 are interconnected, and connected to CDU pin 4 to form a common mode decomposition part.

Furthermore, a cascaded CDU structure is constructed based on CDUs. The 2-level cascaded CDU structure is shown in Figure 3, consisting of 3 CDUs, including 4 input pins and 4 output pins, denoted as CDU-2. In order to simplify the figure, all pin numbers are omitted in the figure, and are characterized by their positions. The input pins are arranged on the left side in ascending order from top to bottom, and all output pins are arranged on the right side in ascending order from top to bottom. The construction method of the 2-level cascaded CDU structure is as follows: Firstly, two CDUs are taken, and their input pins (namely, pin 1 and pin 2) are arranged in sequence to form 4 input pins of the 2-level cascaded CDU structure; The pins 3 of each CDU are arranged in turn to form the first and second output pins of the 2-level cascaded CDU structure; connect the common mode output pins (pin 4) of the two CDUs to the pins of the third CDU respectively pin 1 and pin 2, and then use pin 3 and pin 4 of the third CDU as the third and fourth output pins of the 2-level cascaded CDU structure respectively.

Based on the CDU structure, a multi-level cascaded CDU structure can be constructed. As can be seen from the above, through the 2-level cascading of CDUs, a 2-level cascading CDU structure including 4 input pins and 4 output pins can be formed, which is denoted as CDU-2; similarly, 2 CDU-2 and 1 CDU A circuit structure containing 8 input pins and 8 output pins can be formed, which is denoted as CDU-3; by analogy, 2 CDU-i and 1 CDU can form a circuit structure containing 2i+1 input pins and 2i+1 The circuit structure of output pins is denoted as CDU-{i+1} (i is a positive integer). The connection method of CDU-{i+1} composed of 2 CDU-i and 1 CDU is: use all input pins of the first CDU-i as the 1st to 2ith pins of CDU-{i+1} Input pins, the order remains unchanged; all input pins of the 2nd CDU-i are used as input pins 2i+1 to 2i+1 of CDU-{i+1}, the order remains unchanged; The first 2i-1 output pins of the first CDU-i are used as the first to 2i-1 output pins of CDU-{i+1}, and the first 2i-1 output pins of the second CDU-i are output The pin is used as the 2ith to 2i+1-2 output pins of CDU-{i+1}; connect the 2ith (last) output pin of the 1st CDU-i to the pin 1 of CDU , the 2ith (last) output pin of the second CDU-i is connected to pin 2 of CDU; pin 3 and pin 4 of CDU are respectively used as the 2i+1th of CDU-{i+1} -1 and 2i+1 output pins. Taking CDU-3 as an example, its structure is shown in Figure 4. (The pin numbers are omitted and are characterized by their positions. The input pins are arranged on the left side in ascending order from top to bottom, and all output pins are arranged on the right side in ascending order from top to bottom.)

On the basis of the multi-level full-mode decomposition balun structure, the automatic gating structure can be added to form a complete connectable multi-pair cable, which can perform full-mode decomposition of the cable, and the output pins and instruments can be controlled by digital levels. The cable characteristic test terminal circuit design of the port connected condition. The automatic gating structure is realized based on radio frequency single-pole multi-throw switch and its combination. The specific structure is: the automatic gating structure is realized by a single radio frequency single-pole multi-throw switch and/or a combination of multiple radio frequency single-pole multi-throw switches, with one common pin, multiple multiple pins to be selected and multiple control pins, According to the level value of the control pin, it can be determined which pin to be connected to the shared pin. A typical case is shown in Figure 5. The 8-way RF single-pole multi-throw switch chip (SP8T) can be composed of a 2-way RF single-pole multi-throw switch chip (SPDT) and two 4-way RF single-pole multi-throw switch chips (SP4T). Bit0~Bit2 in the figure are control pins, the pins on the left side of the figure are 8 pins to be selected, and the pins on the right side of the figure connected to the coaxial port of the instrument are common pins.

The overall structure of the cable characteristic test terminal circuit design is shown in Figure 5. The cable under test is connected to the input pin of the multi-level full-mode decomposition balun structure, and the output pin of the multi-level full-mode decomposition balun structure is connected to the multi-channel candidate port of the automatic gating structure; the general pin of the automatic gating structure is connected to the instrument port. Its functional flow is as follows: the transmission signal of the line to be tested is decomposed by the multi-level full-mode decomposition balun structure to obtain the signal of each mode, and input to the automatic gating structure to be selected; then the automatic gating structure decides which channel to use according to the control level Enter the instrument to measure.

The following uses a typical CDU-3-based 4 twisted-pair cable characteristic test termination circuit as a case for illustration. The circuit is shown in Figure 7. J1 in the figure is an 8-bit terminal, connected to 4 twisted pairs. U1-U14 form a balun structure, and its configuration is a 3-level cascade of CDUs. The device model is ETC1-1-13 radio frequency transformer of M/A-COM Company. U15-U17 form an automatic gating structure, and its configuration is SP8T composed of 1 SPDT and 2 SP4T cascaded; among them, U16 is SPDT, and the model selection is ADG918 of Analog Devices; U15 and U17 are SP4T, and the model selection is ADG904 of Analog Devices . J3 is the digital logic that controls the strobe path (2 pins are enabled, 5, 8, and 11 are control bits, and the remaining pins are connected to VCC and GND to provide logic values 1 and 0). J2 is a power socket, external 3.3V DC power supply.

Although the specific implementation methods of the present invention have been described above, those skilled in the art should understand that these are only examples, and various changes or modifications can be made to these embodiments without departing from the principle and realization of the present invention. Therefore, the protection scope of the present invention is defined by the appended claims.

Claims (7)

1. a kind of multistage syntype decomposes barron structure, it is characterised in that: by N number of differential mode decomposition unit CDU altogether, by cascading shape It is further in parallel being constituted and cascade CDU structure between the cascade CDU structure and cascade CDU structure that formula is constituted；N≥ 2, N be positive integer.

2. multistage syntype according to claim 1 decomposes barron structure, it is characterised in that: each CDU has 4 Pin, two of them are input pin, i.e. pin 1 and pin 2, and another two pin is respectively differential mode output pin, i.e. 3 He of pin Common mode output pin, i.e. pin 4；Part is decomposed including differential mode inside CDU and common mode decomposes part, differential mode decomposition part and common mode It decomposes part and is respectively based on a radio-frequency transformer RFT building, differential mode decomposition part and common mode decomposition part are independently realized defeated Enter to hold difference mode signal to decompose and common-mode signal decomposition function；Part decomposed for differential mode, two input pins of CDU and RFT's A pair is connected with phase pin, and another pair of RFT is grounded respectively with phase pin and differential mode output pin；Part is decomposed for common mode, Two input pins of CDU and a pair of of reverse phase pin of RFT connect, and another pair reverse phase pin interconnection of RFT is followed by common mode output Pin.

3. multistage syntype according to claim 1 decomposes barron structure, it is characterised in that: the N constitutes 2 when being equal to 2 Grade cascade CDU structure, 2 grades of cascade CDU structures are made of 3 CDU, and the input pin of two CDU is arranged successively composition 2 4 input pins of grade cascade CDU structure；The differential mode output pin of the two CDU is arranged successively 2 grades of cascade CDU knots of composition 1st and the 2nd output pin of structure；The common mode output pin of the two CDU is connect two of the 3rd CDU respectively, then by The differential mode output pin and common mode output pin of 3 CDU cascade the 3rd and the 4th output pin of CDU structure respectively as 2 grades；It is logical 2 grades of cascades for crossing CDU, constitute 2 grades of cascade CDU structures comprising 4 input pins and 4 output pins.

4. multistage syntype according to claim 1 decomposes barron structure, it is characterised in that: the N is greater than multistage when 2 Cascade CDU structural implementations are as follows: by 2 grades of cascades of CDU, constitute 2 grades of cascades comprising 4 input pins and 4 output pins CDU structure, is denoted as CDU-2；2 CDU-2 and 1 CDU constitute the circuit structure comprising 8 input pins and 8 output pins, It is denoted as CDU-3；Similarly, the case where being greater than 2 for N, it includes 2 that 2 CDU-N and 1 CDU, which constitute one,^N+1A input pin and 2^{N +1}The circuit structure of a output pin is denoted as CDU- { N+1 }；The connection type of CDU- { N+1 } is made of 2 CDU-N and 1 CDU Are as follows: using all input pins of the 1st CDU-N as the 1st to the 2nd of CDU- { N+1 } the^NA input pin, sequentially remains unchanged； Using all input pins of the 2nd CDU-N as the 2nd of CDU- { N+1 } the^N+ 1 to the 2nd^N+1A input pin, sequence are kept not Become；By before the 1st CDU-N 2^N- 1 output pin as CDU- { N+1 } the 1st to the 2nd^N- 1 output pin, by the 2nd Preceding the 2 of CDU-N^N- 1 output pin as CDU- { N+1 } the 2nd^NTo the 2nd^N+1- 2 output pins；By the of the 1st CDU-N 2^NIt is a, i.e., the last one output pin access CDU pin 1, the 2nd of the 2nd CDU-N the^NA the last one i.e. output pin access The pin 2 of CDU；Using the pin 3 of CDU and pin 4 as the 2N+1-1 and 2N+1 output pin of CDU- { N+1 }.

5. multistage syntype according to claim 1 decomposes barron structure, it is characterised in that: described and cascade CDU structure In parallel way are as follows: N number of CDU or cascade CDU structure are numbered 1 to N, successively by the 1st to n-th CDU or cascade CDU The input pin of structure is ranked up, as and cascade the input pin of CDU structure；Successively by the 1st to n-th CDU or cascade The output pin of CDU structure is ranked up, as and cascade the output pin of CDU structure.

6. it is a kind of based on claim 1-5 it is one of any described in multistage syntype decompose the cable characteristic test end of barron structure Connect circuit, it is characterised in that: increase automatic gating structure on the basis of the multistage syntype decomposes barron structure, constituted Whole terminating circuit；Multistage syntype decomposes input terminal of the input terminal of barron structure as the terminating circuit, with cable to be measured Connection；The output end that multistage syntype decomposes barron structure is connected with the input terminal of automatic gating structure；Automatic gating structure Output end of the output end as the terminating circuit, connect with instrument port.

7. cable characteristic test termination circuit according to claim 6, it is characterised in that: the automatic gating structure is based on Radio frequency single pole multiple throw and combinations thereof realizes, specific structure are as follows: automatic gating structure by single radio frequency single pole multiple throw and Or the combination of multiple radio frequency single pole multiple throws is realized, there is 1 common pin, multiple multichannels pin to be selected and multiple controls to draw Foot can determine common pin is connect with which pin to be selected according to the level value of control pin；Multistage syntype decomposes balun Structure input pin is directly connect with tested cable, and output pin is connected with the multichannel port to be selected of automatic gating structure；Automatically The common pin of gating structure is connected with instrument port；Signal, which is transmitted, to survey line decomposes barron structure through multistage syntype To the signal of each pattern, it is to be selected to be input to automatic gating structure；Then it determines to incite somebody to action according to control level by gating structure automatically Which input instrument measures.