JPH09107338A - Interface module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the attenuation characteristic of common mode noise and to reduce crosstalk regardless of miniaturization by forming a reception section and a transmission section independently and arranging components in axial symmetry with respect to a center line. SOLUTION: A reception section and a transmission section are formed at both sides of a center line A-B in the breadthwise direction of a printed circuit board 11 separately. Then a low pass filter 2, a pulse transformer T1 and a choke transformer T3 of the reception section and a low pass filter 3, a pulse transformer T2 and a choke transformer T4 of the transmission section are arranged in axial symmetry with respect to the center line A-B. Then in the characteristic of crosstalk of the interface module 10, an attenuation of 40dB or over is provided at all times for a frequency range of 5-100MHz. Thus, crosstalk between the reception and the transmission sections is suppressed low regardless of miniaturization and thin profile. Furthermore, the attenuation characteristic of common mode noise is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interface module, and more particularly to an interface module used for transmission of digital signals in LAN (local area network), computer-to-computer communication, data terminal communication, and the like.

[0002]

2. Description of the Related Art Conventionally, an interface circuit is used when transmitting a digital signal in a LAN, communication between computers, communication between data terminals, etc., especially when low radiation noise from a transmission line is required. Is used. FIG. 5 is a circuit diagram showing a conventional interface circuit, where 1 is the whole interface circuit,
2 and 3 are low-pass filters, T1 and T2 are pulse transformers, T3 and T4 are choke transformers, 8 is a receiver, and 9
Indicates a driver. Entire interface circuit 1
Is composed of a receiving unit and a transmitting unit, the receiving unit is composed of a low-pass filter 2, a pulse transformer T1 and a choke transformer T3, and the transmitting unit is composed of a low-pass filter 3, a pulse transformer T2 and a choke transformer T4. The low-pass filter 2 removes noise (harmonic components) mixed in the transmission path. The inductors L1 and L2 are connected in series, the inductors L3 and L4 are connected in series, and one end of the inductor L1 and the inductor L3 are connected. Capacitor C between the ends
1 is connected, a capacitor C2 is connected between the connection point of the inductor L1 and the inductor L2, and the connection point of the inductor L3 and the inductor L4, and a series circuit of the capacitors C3 and C4 is formed between one end of the inductor L2 and one end of the inductor L4. Connected. The low-pass filter 3 is for removing harmonic components (normal mode noise). The inductors L5 and L6 are connected in series, the inductors L7 and L8 are connected in series, and one end of the inductor L5 and the inductor L7 are connected. A capacitor C5 is connected between one ends of the inductor L5 and the inductor L6.
A capacitor C6 is connected between the connection point of the inductor L8 and the inductor L8, and a series circuit of the capacitors C7 and C8 is connected between one end of the inductor L6 and one end of the inductor L8. The pulse transformers T1 and T2 electrically separate the input side and the output side to insulate between the input and output, and the choke transformers T3 and T4 use the common mode noise (on the two lines with respect to the ground). The noise generated by the electric potential) is removed. Note that R1 and R2 are matching resistors serving as a load of the receiving unit, and R3, R4, R5, R6, and R7 are resistors for shaping the waveform of the digital signal input to the transmitting unit. The signal at the receiver input has a waveform close to a sine wave,
After the common mode noise is removed by the choke transformer T3, it is converted by the pulse transformer T1, and the noise (harmonic component) mixed in the transmission path is removed by the low pass filter 2 and output to the receiver 8. The signal input to the transmission side is a square-wave digital signal, and this signal is input from the driver 9 to the low-pass filter 3 to remove harmonic components, and has a waveform close to a sine wave. Then, this signal is input to the choke transformer T4 via the pulse transformer T2, and common mode noise is removed.

In such an interface circuit, a plurality of inductors and capacitors forming a low-pass filter, electronic components such as a pulse transformer, a choke transformer, etc. are mounted on the same printed circuit board without distinguishing between the receiving section and the transmitting section. Are soldered together and integrated.

[0004]

In recent years, an interface module integrating such an interface circuit has a thickness of 2.5 m in order to be incorporated in a PC card mounted in a PCMCIA slot of a portable computer.
It is desired to make the thickness within m and to reduce the occupied area. However, in the conventional interface module, the individual components that make up the interface circuit were mounted on the printed circuit board without distinguishing between the receiving section and the transmitting section, so the circuit layout was complicated and miniaturization was difficult. It was If the arrangement interval of the individual components that make up the interface circuit is simply reduced to reduce the size, the frequency used in the interface circuit will be several MHz to several tens of M.
Since it is as high as Hz, there are problems that crosstalk occurs and the attenuation characteristic of common mode noise deteriorates. It is an object of the present invention to provide an interface module which can reduce the occurrence of crosstalk and improve the attenuation characteristics of common mode noise even if the shape is reduced in size and thickness.

[0005]

An interface module according to the present invention comprises a receiving section and a transmitting section each of which includes a low-pass filter, a pulse transformer, a choke transformer, or a low-pass filter and a pulse transformer. The receiving part and the transmitting part are independently formed on both sides of the center line in the width direction on one side of the substrate, and the low pass filter, the pulse transformer and the choke transformer forming the receiving part and the transmitting part are centered on the center line. They are arranged in line symmetry. And
The low-pass filter of the receiving unit and the transmitting unit is a balanced low-pass filter in which a plurality of inductors are formed on a bobbin having a plurality of flanges and a plurality of winding grooves separated by a collar, and a plurality of inductors and a plurality of capacitors are connected to each other. It is what Further, the interface module of the present invention includes a receiving unit and a transmitting unit each having a low-pass filter including a plurality of inductors and a plurality of capacitors, a pulse transformer, a choke transformer, or a low-pass filter including a plurality of inductors and a plurality of capacitors. And a pulse transformer, the receiving section and the transmitting section are independently formed on both sides of the center line in the width direction on one side of the board of the interface module, and the low-pass filter of each of the receiving section and the transmitting section has a plurality of inductors. Is formed on a bobbin having a plurality of collars and a plurality of winding grooves separated by the collar, and is mainly a bobbin, a pulse transformer, and a choke transformer in which a plurality of inductors of respective low-pass filters forming a receiving section and a transmitting section are formed. They are arranged symmetrically about a line. Further, in the interface module of the present invention, the receiving unit and the transmitting unit are configured by a low-pass filter, a pulse transformer, a choke transformer, or a low-pass filter, and a pulse transformer, respectively, and the width direction of one side of the substrate of the interface module is The receiver and transmitter are formed independently on both sides of the center line,
Each of the low-pass filters of the receiver and the transmitter has a plurality of inductors connected in series, and a pair of inductors connected in series to a bobbin having a plurality of collars and a plurality of winding grooves separated by the collars. Is formed symmetrically with one of the plurality of series-connected inductors, and a pair of the plurality of series-connected inductors are connected with a plurality of capacitors to form a low-pass filter for each of the low-pass filter and the low-pass filter. The bobbin, the pulse transformer, and the choke transformer are arranged in line symmetry about the center line.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The receiving section and the transmitting section of an interface module are separately formed on one side of a printed circuit board on both sides of a center line AB in the width direction of the printed circuit board.
Then, the low-pass filter, the pulse transformer, and the choke transformer that configure the receiving unit, and the low-pass filter, the pulse transformer, and the choke transformer that configure the transmitting unit are arranged in line symmetry about the center line AB, and receive the signal. The bobbin, the pulse transformer, and the choke transformer of the low-pass filter forming the unit and the bobbin, the pulse transformer, and the choke transformer of the low-pass filter forming the transmitting unit are also arranged in line symmetry about the center line AB. Therefore, the receiving portion and the transmitting portion of the interface circuit can be formed on only one surface of the printed circuit board, and the circuits of the receiving portion and the transmitting portion do not intersect on the printed circuit board as in the conventional case. In addition, the low-pass filter forming the receiving unit and the low-pass filter forming the transmitting unit each include a pair of inductors connected in series to a bobbin having a plurality of collars and a plurality of winding grooves separated by the collar. It is formed symmetrically with one of the plurality of inductors connected in series. Therefore, the inductors forming the low-pass filters of the receiving unit and the transmitting unit can be integrated, and they are not separately arranged on the printed circuit board and take up space unlike the conventional case.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an interface module of the present invention will be described below with reference to FIGS. FIG. 1 is a top view showing the arrangement of components on a printed circuit board in an embodiment of an interface module of the present invention, and FIG. 2 is a connection diagram of a plurality of inductors and a plurality of capacitors of a low pass filter in the interface module of the present invention. 1 and 2, 10 is an interface module, 11 is a printed circuit board, 12 and 13 are bobbins, and A-
Line B is the center line. In this embodiment, the circuit shown in FIG. 5 is mounted, and the same parts as those in FIG. 5 are designated by the same reference numerals. The interface module 10
The low-pass filter 2, the pulse transformer T1, and the choke transformer T3 that form the receiving unit, and the low-pass filter 3, the pulse transformer T2, and the choke transformer T4 that form the transmitting unit are mounted and integrated on only one side of the printed circuit board 11. The receiving portion and the transmitting portion are provided on one side of the printed circuit board 11 with a center line AB in the width direction of the printed circuit board 11.
And the low pass filter 2, the pulse transformer T1, the choke transformer T3, and the low pass filter 3, the pulse transformer T2, and the choke transformer T4 are arranged in line symmetry about the center line AB. To be done.

The low-pass filter 2 of the receiving section includes inductors L1, L2, L3, L4 and capacitors C1, C2, C.
3 and C4, the inductors L1, L2, L3 and L4 are formed on the bobbin 12. The bobbin 12 includes six flanges, five winding grooves divided into the flanges, a metal plate terminal having a barbed portion and a surface connecting portion provided on the flange, and the inductor L1 is formed in the first winding groove. The inductor L2 is formed in the adjacent second winding groove, and the inductor L2 is formed in the fourth winding groove.
4 is formed, and the inductor L3 is formed in the adjacent fifth winding groove.
Is formed. And inductor L1 and inductor L
2 are connected in series, and inductor L3 and inductor L4
Are connected in series to form a pair. Therefore, this pair of inductors L1 and L2 and inductors L3 and L4
The inductor L1 and the inductor L3 are formed at symmetrical positions, and the inductor L2 and the inductor L4 are formed at symmetrical positions with the third winding groove interposed therebetween. In addition, the low-pass filter 3 of the transmitter includes inductors L5, L6, L7,
L8 and capacitors C5, C6, C7 and C8 are provided, and inductors L5, L6, L7 and L8 are formed on the bobbin 13. The bobbin 13 is provided with six flanges, five winding grooves divided into the flanges, and metal plate terminals having a barb portion and a surface connection portion provided on the collar. Inductors L5, L6, L7,
L8 is formed in a position where the inductor L5 and the inductor L7 are symmetrical with each other with the third winding groove of the bobbin 13 interposed therebetween.
The inductor L6 and the inductor L8 are formed at symmetrical positions. The inductor L5 and the inductor L6 are connected in series, and the inductor L7 and the inductor L8 are connected in series to form a pair. The pulse transformer T1 and the choke transformer T3 are provided with the toroidal cores 14 and 1, respectively.
The pulse transformer T1 is formed by winding a winding wire around
Choke transformer T3 using part of the winding forming
Is formed. The pulse transformer T2 and the choke transformer T4 are also formed by winding the windings around the toroidal cores 16 and 17, respectively. The choke transformer T4 is formed by using a part of the winding forming the pulse transformer T2. And bobbin 12, pulse transformer T1, choke transformer T3, bobbin 13, pulse transformer T
2. The choke transformer T4 is mounted on one surface of the printed circuit board 11 at a position symmetrical about the center line AB. In addition, 18A is an input terminal section of the receiving section of the interface module, 18B is an output terminal section of the receiving section, 1
8C is a ground terminal section of the receiving section, 19A is an input terminal section of the transmitting section of the interface module, 19B is an output terminal section of the transmitting section, and 19C is a ground terminal section of the transmitting section, each formed on the printed circuit board 11 by a wiring pattern. To be done.

The bobbin 12 and the bobbin 1 thus mounted.
In 3, the surface connection portion of each metal plate terminal is connected to the wiring pattern formed on the printed board 11. And
As shown in FIG. 2, a capacitor C1 is provided between one end of the inductor L1 and one end of the inductor L3 via a wiring pattern.
Is connected, a capacitor C2 is connected between the connection point of the inductor L1 and the inductor L2, and the connection point of the inductor L3 and the inductor L4, and a series circuit of the capacitors C3 and C4 is connected between one end of the inductor L2 and one end of the inductor L4. As a result, a low pass filter is formed. Also, one end of the inductor L5 and the inductor L5 are connected via the wiring pattern.
A capacitor C5 is connected between one ends of
A capacitor C6 is connected between a connection point of the inductor 5 and the inductor L6 and a connection point of the inductor L7 and the inductor L8, and a series circuit of the capacitors C7 and C8 is connected between one end of the inductor L6 and one end of the inductor L8. The connection point between the capacitors C3 and C4 and the connection point between the capacitors C7 and C8 are grounded via the ground terminal portion 18C of the receiver and the ground terminal portion 19C of the transmitter, respectively.

Such an interface module 10
The crosstalk characteristic of is as shown in FIG. The horizontal axis represents frequency and the vertical axis represents the amount of attenuation.
This crosstalk characteristic (a) always has an attenuation amount of 40 dB or more, whereas the conventional crosstalk characteristic (b) has an attenuation amount of less than 40 dB at 5 MHz to 100 MHz. The crosstalk between the receiving unit and the transmitting unit is suppressed to a low level by improving it compared with the conventional one.

The common mode noise attenuation characteristic of such an interface module 10 is shown in FIG.
It looks like. The horizontal axis represents frequency and the vertical axis represents the amount of attenuation. This interface module 10
Is a pair of inductors L1 and L2 and inductor L
3, L4 and inductors L5, L6 and inductor L7,
L8 is symmetrically connected by capacitors C1, C2, C3, C4 and capacitors C5, C6, C7, C8, respectively, so that the low-pass filter 2 of the receiving unit and the low-pass filter 3 of the transmitting unit have good balance. Therefore, the common mode noise attenuation characteristic (C) is 5MHz to the common mode noise attenuation characteristic (D) of the conventional one.
While it has an attenuation amount of less than 60 dB at 100 MHz, it always has an attenuation amount of 60 dB or more, which is a significant improvement over the attenuation characteristics of the conventional one.

Although the embodiment of the interface module of the present invention has been described above, the present invention is not limited to this embodiment. For example, metal plate terminals may be attached to the input terminal section, output terminal section, and ground terminal section of the receiving section and the input terminal section, output terminal section, and ground terminal section of the transmitting section.
The interface module may be entirely sealed with resin. The pulse transformer and choke transformer are
They may be separately formed and connected via a wiring pattern or the like. Moreover, the choke transformers of the receiving unit and the transmitting unit can be omitted. Furthermore, the resistors R1, R2, R3, R4,
R5, R6, and R7 may be mounted on a printed circuit board. In the present embodiment, the low-pass filters of the receiving unit and the transmitting unit have two inductors connected in series on the bobbin, but two or more inductors connected in series on the bobbin are two. It goes without saying that the present invention can be applied to the one formed.

[0013]

As described above, in the interface module of the present invention, the receiving section and the transmitting section are each constituted by a low-pass filter, a pulse transformer and a choke transformer, and the center of one side of the board of the interface module in the width direction is centered. Since the receiving unit and the transmitting unit are independently formed on both sides of the line, and the low-pass filter, the pulse transformer, and the choke transformer forming the receiving unit and the transmitting unit are arranged in line symmetry about the center line, Even if the shape is made smaller and thinner, the occurrence of crosstalk can be suppressed and the common mode noise attenuation characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a top view showing the arrangement of components on a printed circuit board in an embodiment of an interface module of the present invention.

FIG. 2 is a connection diagram of a plurality of inductors and a plurality of capacitors of a low pass filter in the interface module of the present invention.

FIG. 3 is a characteristic comparison diagram of crosstalk.

FIG. 4 is a comparison diagram of common mode noise attenuation characteristics.

FIG. 5 is a circuit diagram showing a conventional interface circuit.

[Explanation of symbols]

 2 Low-pass filter 3 Low-pass filter 10 Interface module 11 Printed circuit board 12 Bobbin 13 Bobbin

Claims (7)

[Claims] 1. An interface module comprising a low-pass filter, a pulse transformer, and a choke transformer as the receiving unit and the transmitting unit, respectively, and the receiving unit on both sides of the center line in the width direction of the interface module. And the transmission unit are formed independently, and the low-pass filter, the pulse transformer, and the choke transformer that form the reception unit and the transmission unit are arranged in line symmetry about the center line. Interface module. 2. An interface module comprising a receiving section and a transmitting section each comprising a low-pass filter and a pulse transformer, which are integrated with each other, and the receiving section and the transmitting section are provided on both sides of the center line in the width direction of the interface module. An interface module, characterized in that the low-pass filters and the pulse transformer, which are formed independently of each other and constitute a receiving section and a transmitting section, are arranged in line symmetry about a center line. 3. The low-pass filter of the receiving section and the transmitting section, wherein each of the plurality of inductors is formed on a bobbin having a plurality of collars and a plurality of winding grooves separated by the collars, and the plurality of inductors and the plurality of capacitors. 3. The interface module according to claim 1, wherein the interface module is a balanced low-pass filter. 4. The receiving unit and the transmitting unit are configured by a low-pass filter including a plurality of inductors and a plurality of capacitors, a pulse transformer, and a choke transformer, respectively.
In the integrated interface module, the receiving unit and the transmitting unit are independently formed on both sides of the center line in the width direction of the interface module, and the low-pass filter of each of the receiving unit and the transmitting unit has a plurality of inductors. , A bobbin formed on a bobbin having a plurality of winding grooves separated by the tsuba, and a plurality of inductors of each of the low-pass filters forming a receiving section and a transmitting section, a pulse transformer, and a choke transformer are mainly formed. An interface module characterized by being arranged in line symmetry about a line. 5. An interface module in which a receiving section and a transmitting section each include a low-pass filter including a plurality of inductors and a plurality of capacitors, and a pulse transformer, and the center line in the width direction of the interface module is integrated in the interface module. A receiving unit and a transmitting unit are independently formed on both sides of each of the low-pass filters of the receiving unit and the transmitting unit, and a plurality of inductors are provided on a bobbin having a plurality of flanges and a plurality of winding grooves separated by the collars. An interface module in which a bobbin and a pulse transformer, which are formed and in which a plurality of inductors of the respective low-pass filters forming the receiving unit and the transmitting unit are formed, are arranged in line symmetry about a center line. 6. An interface module comprising a low-pass filter, a pulse transformer, and a choke transformer as the receiving unit and the transmitting unit, respectively, and the receiving unit on both sides of the center line in the width direction of the interface module. And a transmitter are independently formed, and each of the low-pass filters of the receiver and the transmitter has a plurality of inductors connected in series, and a bobbin having a plurality of collars and a plurality of winding grooves separated by the collars. A pair of the plurality of series-connected inductors are respectively formed symmetrically with one series-connected plurality of inductors, and the pair of series-connected inductors are connected by a plurality of capacitors. , A bobbin, a pulse transformer, and a choke transformer of each of the low-pass filters constituting the receiving unit and the transmitting unit have a center line as an axis An interface module characterized by being arranged in line symmetry. 7. An interface module in which the receiving section and the transmitting section are each constituted by a low-pass filter and a pulse transformer, and these are integrated, the receiving section and the transmitting section are provided on both sides of the center line in the width direction of the interface module. The low pass filter of each of the receiving section and the transmitting section is independently formed, and a plurality of inductors are connected in series to a bobbin having a plurality of collars and a plurality of winding grooves separated by the collars. The plurality of inductors connected in series are formed symmetrically with one of the plurality of inductors connected in series, and the pair of inductors connected in series are connected to each other by a plurality of capacitors. The bobbin and the pulse transformer of each of the low-pass filters forming the transmitter are arranged in line symmetry about the center line. Interface module.