JP3147520B2 - Integrated circuit for transmission line interface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line interface integrated circuit, and more particularly to a transmission line interface integrated circuit applied to a communication system including a transmission line and a plurality of communication control devices.

[0002]

2. Description of the Related Art In a home, an industrial field, or the like, mutual communication between devices is performed by, for example, a configuration as shown in FIG. That is, FIG. 4 shows a communication system in which a plurality of transmission line interface units 38a, 38b, 38c and communication control devices 39a, 39b, 39c are electrically connected on the transmission lines 1 and 1 '. is there. And FIG.
In the communication system of (1), when transmitting a communication frame from the own station to another station, the communication control devices 39a, 39b, and 39c generate a predetermined communication frame and transmit the predetermined communication frame to the transmission line interface units 38a, 38b, and 38c. After the conversion, the data is sent out onto the transmission lines 1 and 1. On the other hand, when a communication frame addressed to the own station is received from another station, the communication frames carried from the transmission lines 1 and 1 'are subjected to predetermined conversion in the transmission line interface units 38a, 38b and 38c. Communication control devices 39a, 39b, 39
c to decode the communication frame. The transmission line interface units 38a, 38b, 38c in FIG.
A conventional example of the communication control devices 39a, 39b, 39c will be described in more detail with reference to FIG.

FIG. 5 shows a transmission line interface unit 38.
A conventional example in which a, 38b, and 38c are configured by a semiconductor integrated circuit, and a part of the communication control devices 39a, 39b, and 39c are configured by a semiconductor integrated circuit. In FIG. 5, an input point of the converter 2 forming the receiver circuit 28 and an output point of the converter 3 forming the driver circuit 29 are connected to the transmission lines 1 and 1 ′ via terminals 17 and 16. ing. The output of the receiver circuit 28, that is, the output of the converter 2 is output from a terminal 33, and the input of the driver circuit 29, that is, the input of the converter 3, is input from a terminal 34. Here, the converter 2 and the converter 3 are formed on the same semiconductor integrated circuit board, and together with the terminals 16, 17, 33, 34, form a transmission line interface integrated circuit 30.

The output of the receiver circuit 28 taken out from the terminal 33 is input to the input point of the buffer 8 constituting the interface circuit 10 via the terminal 35, and the output of the buffer 8 is input to the reception processing circuit 11. On the other hand, the output of the transmission processing circuit 12 is
0 is input to the buffer 9. The output of the buffer 9 is input to the driver circuit 29 via the terminal 36 and the terminal 34 of the transmission line interface integrated circuit 30. The reception processing circuit 11 and the transmission processing circuit 12 are connected to a communication control circuit 31. These reception processing circuits 11,
The transmission processing circuit 12, the communication control circuit 31, and the interface circuit 10 together with the terminals 35 and 36 constitute a communication control integrated circuit 32.

Next, the communication control integrated circuit 3 shown in FIG.
2. A communication control device (own station) constituted by the transmission line interface integrated circuit 30 communicates with a communication control device (other station) connected in a similar configuration on the transmission lines 1 and 1 '. The operation in the case of performing is described. When the own station transmits a frame to another station, the transmission processing circuit 12 is controlled by the communication control circuit 31 to generate a communication frame for the destination station. Here, the communication frame includes, for example, synchronization information, own station address information, transmission destination station address information, a message to be transmitted, a control code, and the like, which are formed into a digital signal sequence of "1" and "0". ing. The communication frame generated by the transmission processing circuit 12 is
The digital signal is output from a terminal 36 via a buffer 9 and is input to a driver circuit 29 of the integrated circuit 30 for a transmission line interface via a terminal 34. After the above-mentioned communication frame signal to be transmitted is converted under a predetermined condition by the converter 3 constituting the driver circuit 29,
The data is transmitted on the transmission lines 1 and 1 '.

The converter 3 has a signal format conversion including a function of converting an output level of a communication frame input as a digital signal, and a drive function for transmitting the format-converted signal onto a transmission line. Perform signal processing. When a communication frame is transmitted from another station to the own station, the communication frame processed by the transmission processing operation as described above at the transmission destination is transmitted to the terminal 1.
The signal is input to the receiver circuit 28 via the channels 6 and 17. The converter 2 forming the receiver circuit 28 processes the input signal according to a characteristic substantially opposite to that of the converter 3 forming the driver circuit 29. That is, it has an inverse format conversion function including a function of converting a signal level into a condition that allows the format-converted signal to be handled as a communication frame as a digital signal at the next stage, and a buffer function for inputting a signal from a transmission path. To perform analog processing. The communication frame processed by the receiver circuit 28 is output from the terminal 33 and is input from the terminal 35 to the reception processing circuit 11 via the buffer 8 of the communication control integrated circuit 32. The reception processing circuit 11 is controlled by a communication control circuit 31, decodes a communication frame from a transmission partner by digital signal processing, and, based on the contents, various terminal devices electrically connected to the communication control integrated circuit 32 (FIG. (Not shown)) and control.

[0007] Then, by applying the communication control integrated circuit 32 and the transmission line interface integrated circuit 30 shown in FIG. 5 to a communication system as shown in FIG. 4, mutual communication is performed via a transmission line. Can do things. Further, as shown in FIG. 5, the analog signal processing section and the digital signal processing section are individually integrated into an integrated circuit under conditions suitable for each processing, thereby enabling more economical communication.

[0008]

However, when the present invention is applied to actual communication between devices, the length of a transmission line, impedance conditions, the number of connected communication control devices, and the like are various. In particular, various distortions occur in the communication signal carried on the transmission line due to the transmission line impedance condition that occurs in a distributed manner. Therefore, in the conventional example of FIG. 5, there is a possibility that the communication signal waveform distortion may affect communication.

To reduce the above-mentioned waveform distortion, FIG.
As shown in the example, the equalizer 37 may be inserted between the terminals 16 and 17 of the transmission line interface integrated circuit 30 and the transmission lines 1 and 1 'to perform waveform equalization. . With this configuration, when the own station receives a transmission signal from another station, it equalizes the waveform by the equalizer 37, thereby reducing the influence of the transmission distortion and then receiving the signal from the receiver circuit 28.
Can be entered.

However, in the conventional example shown in FIG. 6, the waveform equalization characteristic of the equalizer is uniquely determined. Therefore, the transmission distortion generated in various forms depending on the transmission line impedance condition generated as a distributed constant. Is difficult to reduce sufficiently. Further, since this equalizer is constructed independently of the above-mentioned integrated circuit for the transmission line interface, the cost is high. Furthermore, if the characteristics of the equalizer are to be changed adaptively, there is a disadvantage that the hardware for realizing this is increased and the cost is further increased.

It is an object of the present invention to provide a transmission line interface integrated circuit suitable for a communication system including a transmission line and a plurality of communication control devices.

[0012]

According to the present invention, signal waveform equalizing means for reducing transmission distortion, first converting means, second converting means, and first interface means are provided on the same semiconductor integrated circuit substrate. In the integrated circuit for transmission line interface configured as described above, the signal waveform equalizing means may include a gyro.
A signal from another station that has been conveyed on the transmission path, and then outputs the signal to the first conversion means. The first conversion means The waveform-equalized signal is output to a reception processing circuit configuring a communication control device via a second interface unit, and the second conversion unit has an output point connected to the transmission line, A signal transmitted from a transmission processing circuit included in the communication control device and transmitted to another station is received via a third interface unit and output on the transmission path. Generated by the communication control circuit according to the quality of the reception signal processed by the reception processing circuit, and generated by the pulse width modulation circuit.
Ri is configured, the control signal output via the fourth interface means, constituted by a smoothing circuit, the first input from the interface unit, the signal waveform of the output of said first interface means or the like Input to a control input point of the converting means and smoothed by the smoothing circuit.
The operation of the signal waveform equalizing means is controlled by the control signal, whereby a transmission line interface integrated circuit is obtained.

[0013]

[0014]

[0015]

In the present invention, the signal waveform equalizing means receives a communication signal from the communication control device of the own station and another station, and a necessary signal from a transmission line on which the communication control signal is electrically carried. 1 to the conversion means. The output of the first conversion means is input to the input point of the second interface means constituting the communication control device, and the output of the third interface means constituting the communication control device causes the communication control device to transmit to another station. The transmission signal to be transmitted to the second
To the transmission path via the conversion means.

The signal waveform equalizing means inputs a control signal output from the communication control device through a fourth interface means constituting the communication control device from the first interface means, and An output of the first interface means is input to a control input point of the signal waveform equalizing means, and the operation of the signal waveform equalizing means is controlled by a control signal input to the control input point.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an integrated circuit for a transmission line interface according to an embodiment of the present invention, in which the same operations as those of the conventional example shown in FIGS. In FIG. 1, terminals 16,
The output point of the converter 3 constituting the driver circuit 29 is connected to the input point of the equalizer 4 via the circuit 17. The output of the equalizer 4 is connected to the input of the converter 2. The equalizer 4 and the converter 2 constitute a receiver circuit 6.
The output of the receiver circuit 6, that is, the output of the converter 2, is connected to the terminal 1
8 and is input to the buffer 8 constituting the interface circuit 10 via the terminal 21. Buffer 8
Is input to the reception processing circuit 11.

On the other hand, the output from the transmission processing circuit 12 is input to the buffer 9 constituting the interface circuit 10. The output of the buffer 9 is input to the input point of the driver circuit 29 via the terminals 22 and 19, that is, to the input point of the converter 3. The control input / output of the communication control circuit 13 is
When connected to the reception processing circuit 11 and the transmission processing circuit 12, respectively. Separately, a control output of the communication control circuit 13 is connected to an input of the interface circuit 14.
The output of the interface circuit 14 is input to the interface circuit 5 via the terminals 23 and 20, and the output of the interface circuit 5 is connected to the control input point of the equalizer 4.

Here, the receiver circuit 6, the driver circuit 2
9, the interface circuit 5 is formed on the same semiconductor integrated circuit board, and the terminals 16, 17, 18, 19, 2
0 together with the transmission line interface integrated circuit 7. The reception processing circuit 11, the transmission processing circuit 12, the communication control circuit 13, the interface circuit 10, and the interface circuit 14, together with the terminals 21, 22, and 23, constitute a communication control integrated circuit 15.

Next, the communication control integrated circuit 1 shown in FIG.
5. The communication control device (own station) configured by the transmission path interface integrated circuit 7 communicates with the communication control device (other station) connected in the same configuration on the transmission lines 1 and 1 '. The operation when performing the operation will be described. That is, when the own station transmits a communication frame to another station, the transmission processing circuit 12 is controlled by the communication control circuit 13 to generate a communication frame for the destination station. Transmission processing circuit 1
The communication frame generated at 2 is output as a digital signal from terminal 22 via buffer 9 and
9 is input to the driver circuit 29 of the transmission line interface integrated circuit 7. Then, the communication frame transmitted by the converter 3 constituting the driver circuit 29 is converted under a predetermined condition, and then transmitted onto the transmission lines 1 and 1 '.

Here, the converter 3 performs the same operation as the converter 3 shown in the conventional example in FIG. Further, when a communication frame is transmitted from another station to the own station, the communication frame processed by the transmission processing operation similar to the above at the transmission destination constitutes the receiver circuit 6 via the terminals 16 and 17. The signal is input to the equalizer 4, where the waveform of the communication frame signal carried on the transmission path is equalized. At this time, the waveform equalization characteristic of the equalizer 4 is adaptively changed according to a control signal from the communication control circuit 13. That is, the communication control circuit 1
3 generates a control signal according to the quality of a communication frame processed in the reception processing circuit 11 through the equalizer 4. The control signal is transmitted to the interface circuit 1
4. Output to the control input of the equalizer 4 via the interface circuit 5, and apply feedback so that the equalizer 4 has appropriate waveform equalization characteristics. The output of the equalizer 4 is input to the converter 2, and the output of the converter 2 is input to the buffer 8 via the terminals 18 and 21, and the output of the buffer 8 is input to the reception processing circuit 11, and Decrypts the communication frame from.

When receiving the communication frames from the transmission lines 1 and 1 'as described above, the equalizer 4 equalizes the waveforms and then performs predetermined conversion by the converter 2 to perform communication control at the next stage. The control signal from the communication control circuit 13 of the communication control integrated circuit 15 is output to the reception processing circuit 11 via the buffer 8 of the control integrated circuit 15, and the control signal of the equalizer 4 is controlled via the interface circuits 14 and 15. By giving it to the input, the waveform equalization characteristics of the equalizer 4 can be changed adaptively.

FIG. 2 shows a second embodiment of the integrated circuit for transmission line interface according to the present invention. FIG. 2 shows an embodiment in which the interface circuit 5 of the transmission line interface integrated circuit 7 in the embodiment of the present invention shown in FIG. 1 is realized by smoothing means, and the interface circuit 14 of the communication control integrated circuit 15 is pulse width modulated (hereinafter abbreviated as PWM). ) Means. In FIG. 2, the control output of the communication control circuit 13 is input to a PWM circuit 25, pulse width modulated, and then input to a smoothing circuit 26 via terminals 23 and 20.
After smoothing the control signal that has become the PWM signal, the control signal is applied to the control input of the equalizer 4. Incidentally, in FIG.
Is a smoothing capacitor in the smoothing circuit 26.

FIG. 3 shows a third embodiment of the present invention. FIG.
FIG. 5 shows an example in which the equalizer 4 in the second embodiment of the transmission line interface integrated circuit of the present invention shown in FIG. In FIG. 3, the waveform equalization characteristic formed by the gyrator circuit 40 is changed by a smoothed control signal provided from the smoothing circuit 26. The gyrator circuit 40 can be realized by a transistor, a resistor, a capacitor, and the like. Further, since an inductance element such as a coil is not used, this is a more advantageous means for forming on an integrated circuit.

As described above, as an interface function between the transmission line and the communication control integrated circuit processed by digital signal processing, a driver circuit for transmitting a communication frame onto the transmission line and a communication frame from the transmission line are input. An equalizer that performs waveform equalization, a converter that has a conversion function that converts the output from the equalizer to a condition that can be treated as a communication frame as a digital signal in the next stage, and a communication control integrated circuit. The interface circuit that inputs the control signal of the above and converts it into the control signal for the equalizer is configured on the same semiconductor integrated circuit board.
When a communication frame is received from a transmission path, adaptive waveform equalization for transmission distortion generated during transportation can be realized at low cost.

[0026]

As described above, according to the integrated circuit for a transmission line interface of the present invention, when receiving a communication frame from a transmission line, adaptive waveform equalization for transmission distortion generated during the transfer is achieved. It is possible to provide an integrated circuit for a transmission line interface which can be realized at low cost and is suitable for a communication system including a transmission line and a plurality of communication control devices.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a transmission line interface integrated circuit according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of a transmission line interface integrated circuit according to the present invention.

FIG. 3 is a block diagram showing a third embodiment of a transmission line interface integrated circuit according to the present invention.

FIG. 4 is a block diagram illustrating an example of a communication system.

FIG. 5 is a block diagram showing an example of a conventional transmission line interface integrated circuit.

FIG. 6 is a block diagram showing another conventional example.

[Explanation of symbols]

 1,1 'transmission path 2,3 converter 4,37 equalizer 5,10,14 interface circuit 6,28,41 receiver circuit 7,30 transmission path interface integrated circuit 8,9 buffer 11 reception processing circuit 12 transmission Processing circuit 13, 31 Communication control circuit 15, 32 Communication control integrated circuit 16 to 24, 33 to 36 Terminal 25 PWM circuit 26 Smoothing circuit 27 Capacitor 29 Driver circuit 38a to 38c Transmission path interface unit 39a to 39c Communication control device 40 Gyrator circuit

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 3/00-3/44

Claims (1)

(57) [Claims] An integrated circuit for a transmission line interface in which a signal waveform equalizing means for reducing transmission distortion, a first converting means, a second converting means, and a first interface means are formed on the same semiconductor integrated circuit board. In the above, the signal waveform equalizing means is constituted by a gyrator circuit , and after performing a waveform equalization of a signal from another station carried on the transmission path , outputs the signal to the first converting means. The first converting means outputs the waveform-equalized signal to a reception processing circuit constituting a communication control device via a second interface means, and the second converting means An output point is connected to the transmission path and receives, via a third interface means, a signal output from a transmission processing circuit constituting the communication control device and transmitted to another station, and It is output on a transmission path, and is generated according to the quality of a received signal processed by the reception processing circuit from a communication control circuit constituting the communication control device,
The control signal output via the fourth interface means , which is constituted by the pulse width modulation circuit, is sent to the smoothing circuit.
And inputting an output of the first interface means to a control input point of the signal waveform equalizing means, wherein the smoothing circuit comprises:
Wherein the operation of the signal waveform equalizing means is controlled by the control signal smoothed by the control circuit.