JPH0744473A - Signal transmission reception circuit - Google Patents

Abstract

PURPOSE:To send/receive plural signals between a sender side circuit and a receiver side circuit in parallel with a few signal lines with almost immunity to noise effect. CONSTITUTION:Output drive circuits 4-7 in a sender side circuit 1 drive corresponding signal lines 22-25 in response to received signals A-D and a reference voltage generating circuit 3 generates a reference voltage with a predetermined voltage relation to a signal voltage from each output drive circuit to provide an output to a signal line 26. Each of voltage comparators 8-11 of a receiver side circuit 2 compares a reference voltage from a certain signal line with a signal voltage from a signal line connecting to a corresponding output drive circuit and regenerate signals E-H inputted to the corresponding output drive circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission / reception circuit, and is applied to, for example, an input / output configuration for exchanging a plurality of signals in parallel between two constituent elements used in a communication device or a computer. I will get it.

[0002]

2. Description of the Related Art As communication devices and computers operate faster,
It is also required to increase the speed of signals transmitted and received between a plurality of constituent elements, and it is widely practiced to parallelize and transmit a signal between a plurality of constituent elements. For example, even between two integrated circuits (or between two components in the integrated circuit or between two printed wiring boards), one unit signal (for example, byte or word) is transmitted by a plurality of (for example, eight) signal lines. Transfers are made in parallel.

Conventionally, a plurality of signals are paralleled from a transmission side (output side) circuit, which is partially or wholly formed by an integrated circuit, to a reception side (input side) circuit, which is partially or entirely formed by an integrated circuit. The following methods were available for sending and receiving to and from.

The first method is a TTL logic integrated circuit (for example, SN74LS244 manufactured by Texas Instruments) or ECL.
This method is often applied to logic integrated circuits (for example, MC10176 manufactured by Motorola Co.), and each signal is transmitted depending on whether the potential of one signal line is higher or lower than the reference potential of the receiving side circuit. is there. The second method is
Differential input type ECL logic integrated circuit (for example, manufactured by Motorola)
MC10116), which is a method that is often applied.
This is a method in which two signal lines are paired and each of the parallel signals is transmitted by the potential difference between the two signal lines.

[0005]

However, according to the first conventional method of transmitting and receiving a plurality of signals, since each signal is transmitted by one signal line, the noise superimposed on the signal line and the reference potential of the receiving side circuit are reduced. It has a problem that it is weak against the superimposed noise. In particular, when the signal amplitude is selected to be small in order to realize high speed, it is susceptible to noise, and there is a restriction that the transmission distance must be shortened.

On the other hand, the second method of transmitting and receiving a plurality of signals transmits each signal as the potential difference between the pair of signal lines, and therefore is strong against the noise commonly superimposed on the pair of signal lines. As a result, this is an advantageous method when the signal amplitude is reduced in order to realize high speed. However, in the second method of transmitting and receiving a plurality of signals, the number of signals transmitted and received by the signal lines is required to be twice, and the larger the number of signals, the larger the number of signal lines. As a result, the routing of the signal line tends to be complicated. In addition, the number of input / output terminals of the transmitting side circuit and the receiving side circuit is increased, and the physical size of these circuits (for example, an integrated circuit package) is increased, and the power consumption is increased due to the large number of input / output terminals. Let

The present invention has been made in consideration of the above points, and transmits and receives a plurality of signals in parallel between a transmitting side circuit and a receiving side circuit with little influence of noise and with a small number of signal lines. It is an object of the present invention to provide a signal transmitting / receiving circuit capable of performing the above.

[0008]

In order to solve such a problem, in the present invention, a signal transfer circuit for transferring a plurality of signals in parallel between a transmitting side circuit and a receiving side circuit connected by a plurality of signal lines. Was configured as follows.

That is, the transmission side circuit and the reception side circuit are connected by a signal line that is larger than the number of signals to be transmitted and received by one.
Then, the transmission side circuit, a plurality of output drive circuits corresponding to the number of signals for driving the corresponding signal line according to the input signal,
A reference voltage generating circuit for generating a reference voltage having a predetermined voltage relationship with the signal voltage from each output drive circuit and outputting the reference voltage to one signal line is provided. Further, the receiving side circuit is provided with a number of voltage comparators for comparing the reference voltage from one signal line with the signal voltage from the signal line connected to the corresponding output drive circuit, in a number corresponding to the number of signals. .

[0010]

In the present invention, each output drive circuit of the transmission side circuit drives the corresponding signal line in accordance with the input signal, and the reference voltage generation circuit has a predetermined voltage relationship with the signal voltage from each output drive circuit. It generates a certain reference voltage and outputs it to one signal line. In the receiving side circuit, the voltage comparator is inputted to the corresponding output drive circuit by comparing the reference voltage from one signal line with the signal voltage from the signal line connected to the corresponding output drive circuit. Signal is played back.

As a result, a plurality of signals can be transmitted / received in parallel and with a small number of signal lines with little influence of noise.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a digital signal transfer circuit will be described in detail below with reference to the drawings. Here, FIG. 1 is a block diagram showing the configuration of this embodiment.

In FIG. 1, in this embodiment, four digital signals A, B, C and D are sent to a transmitting side circuit (output side circuit) 1
Is transmitted to the receiving side circuit (input side circuit) 2, and the receiving side circuit 2
Are digital signals E (A), F (B), G
(C) and H (D).

The transmission side circuit 1 is configured to transmit each transmission digital signal A,
Output drive circuits 4, 5, respectively corresponding to B, C, D
6 and 7, and a reference voltage generation circuit 3 which gives a reference for the output voltage of these output drive circuits 4 to 7. on the other hand,
The receiving side circuit 2 has four voltage comparators 8, 9, 10, 11
Have.

The output terminal of the output drive circuit 4 is connected to one end of the signal line 22 via the output terminal 12 of the transmission side circuit 1 on which the output drive circuit 4 is mounted, and the other end of the signal line 22 is connected to the reception side. It is connected to the comparison input terminal of the voltage comparator 8 via the input terminal 17 of the circuit 2. Similarly, the output terminals of the other output drive circuits 5, 6, and 7 are connected via the corresponding output terminals 13, 14, and 15 of the transmission side circuit 1 to the corresponding signal lines 23,
The signal lines 23, 2 are connected to one end of 24, 25.
The other ends of 4 and 25 are the corresponding input terminals 1 of the receiving side circuit 2.
Via the corresponding voltage comparators 9, 10,
It is connected to 11 comparison input terminals.

As described above, the output terminal of the reference voltage generating circuit 3 is connected to the reference input terminals of the output drive circuits 4 to 7, and the signal line 26 is connected via the output terminal 16 of the transmitting side circuit 1. It is connected to one end, and the other end of the signal line 26 is connected to the reference input terminals of all the voltage comparators 8 to 11 via the input terminal 21 of the receiving side circuit 2.

As described above, in this embodiment, the transmission side circuit 1 and the reception side circuit 2 receive the transmitted digital signals A (E), B (F), C (G), and D (H). 1 from the number
Only five signal lines 22 to 26 are connected.

Next, the operation of the signal transmission / reception circuit of the embodiment having the above configuration will be described. Note that the levels of the signal lines (transmission paths) 22 to 25 will be described here as conforming to the standard level of the ECL integrated circuit.

A reference voltage of, for example, -1.3 V is applied from the reference voltage generating circuit 3 to each of the output drive circuits 4, 5, 6, and 7, and each of the output drive circuits 4, 5, 6, 7 is By using this reference voltage, when the corresponding digital signals A, B, C, D inputted are logic "1", the signals of -0.9V are outputted to the corresponding output terminals 12, 13, 14, 15. Outputs a voltage, while the corresponding digital signal A input,
When B, C and D are logic "0", the corresponding output terminal 1
A signal voltage of -1.7 V is output to 2, 13, 14, and 15. The −1.3 V reference voltage generated by the reference voltage generation circuit 3 is output to the output terminal 16.

Output terminals 12, 13, 1 of the transmission side circuit 1
The voltages of 4 and 15 (voltages corresponding to transmission / reception signals) are respectively transmitted through the signal lines 22, 23, 24, 25 and the input terminals 17, 18, 19, 20 of the receiving side circuit 2 to the voltage comparators 8, It is applied to the comparison input terminals of 9, 10, and 11. On the other hand, the voltage of the output terminal 16 of the transmission side circuit 1 (reference voltage)
Is applied to the reference input terminals of all the voltage comparators 8, 9, 10, 11 via the signal line 26 and the input terminal 21 of the receiving side circuit 2 in order.

In each of the voltage comparators 8, 9, 10 and 11, for example, the voltage applied to the comparison input terminal (the voltage corresponding to the transfer signal: -0.9V or -1.7V) is applied to the reference input terminal. Output voltage (reference voltage: -1.3V), the logic "1" digital signals E, F, G, and H are output as received digital signals, and the voltage applied to the comparison input terminal is the reference input terminal. When the voltage is smaller than the voltage applied to, the digital signals E, F, G, and H of logic "0" are output as reception digital signals.

For example, when a digital signal A of logic "1" is input to the output drive circuit 4 of the transmission side circuit 1, a signal voltage of -0.9V is output to the output terminal 12, and this voltage is output to the signal line. 22 and the input terminal 17 of the receiving side circuit 2 are applied to the comparison input terminal of the voltage comparator 8 and are compared with the reference voltage −1.3 V transmitted from the transmitting side circuit 1, and from the voltage comparator 8. A digital signal E having the same logic "1" as the digital signal A is output.

During this transmission, the signal lines 22 and 2
Even if noise is mixed in 6, noise is mixed in the signal lines 22 and 26 substantially in the same manner, and the potential difference between the signal lines 22 and 26 is substantially the same as the case where noise is mixed in. is there. Therefore, the voltage comparator 8 outputs the digital signal E having the same logic as that when noise is not mixed.

As described above, the receiving side circuit 2 corresponds to the plurality of digital signals A, B, C and D of the transmitting side circuit 1.
In, the digital signals E, F, G and H are reproduced.

Therefore, according to the above-described embodiment, the reference voltage (reference signal) is transmitted from the transmission side circuit 1 to the reception side circuit 2 in addition to the original transmission / reception signals A to D. The original transmission / reception signal can be transmitted without being affected by noise (including the ground potential difference between the transmission side and the reception side), and malfunctions of the circuit portion using the reception digital signals E to H can be prevented in advance. be able to.

By the way, in the first conventional method of transmitting and receiving a plurality of signals, the noise mixed in the signal line and the ground potential difference between the transmitting side circuit and the receiving side circuit could not be canceled. According to this, the noise mixed in the signal line can be canceled by the voltage comparison, and the ground potential difference between the transmission side circuit and the reception side circuit does not become a problem due to the transmission of the reference voltage.

Further, according to the above embodiment, the above effect (improvement of transmission quality) is obtained with a small number of signal lines.
The second conventional multi-signal transmission / reception method also has the effect of improving the transmission quality. However, although eight signal lines are required for transmitting / receiving, for example, four signals in the second conventional plural signal transmitting / receiving method, this embodiment requires only five signal lines as described above. As a result, it is possible to easily route the signal line, reduce the number of input / output terminals of the transmitting side circuit and the receiving side circuit, simplify the circuit structure, and reduce the power consumption.

Although the number of signals to be transmitted and received is four in the above embodiment, the present invention can be applied to any number of signals such as eight and sixteen. Further, the present invention can be similarly applied to the case where the signal level is not only ECL but also another digital signal level such as TTL.

Further, although the case where the signal to be transmitted and received is a digital signal has been shown in the above embodiment, the technical idea of the present invention can be applied to an analog signal. In this case, an amplifier having a linear input / output characteristic is applied as the output drive circuit (4 to 7), and a differential amplifier (in the claims, this is used instead of the voltage comparator (8 to 11)). The differential amplifier is also called a voltage comparator).

Further, in the above embodiment, the relationship between the transmitting side circuit 1 and the receiving side circuit 2 and the integrated circuit was not mentioned, but the signal transmitting / receiving circuit is realized by various relationships as follows. May be.

(1) Reference voltage generation circuit 3 and output drive circuit 4
7 and the partial components of the voltage comparators 8 to 11 may be realized by individual integrated circuit chips. In such cases,
The transmitter circuit 1 and the receiver circuit 2 correspond to (a part of) a printed wiring board, for example. (2) The entire transmitting side circuit 1 and the entire receiving side circuit 2 may each be configured by an integrated circuit chip. (3) The transmitting side circuit 1 may be provided in the output section of the integrated circuit chip, and the receiving side circuit 2 may be provided in the input section of another integrated circuit chip.

In the cases (2) and (3) of using the integrated circuit,
In the transmission side circuit 1, it is not always necessary to apply the reference voltage from the reference voltage generation circuit 3 to the output drive circuits 4, 5, 6, and 7, and it is possible to utilize the fact that the element constants on the integrated circuit are uniform, It is easy to maintain the accuracy of the relationship between the 16 reference voltages (reference signals) and the output voltages of the output terminals 12, 13, 14, and 15.

In order to realize an integrated circuit, it is desirable that the number of input / output terminals is small, but the present invention can meet such a requirement.

Although the present invention has been made in consideration of a device for parallelizing and transmitting a signal between constituent elements such as a communication device and a computer, the present invention parallelizes a plurality of unrelated signals. It can also be applied to what is given and received.

FIG. 1 shows the simplest configuration, and the present invention is not limited to this. For example, in the above embodiment, one receiving side circuit 2 is shown, but the signal lines 22 to 26 are branched to transmit a signal from one transmitting side circuit 1 to a plurality of receiving side circuits 2. The present invention can be applied to the case. Further, one transmission side circuit 1 and one reception side circuit 2 may be provided with a plurality of sets of output drive circuits and voltage comparators having different reference voltages. In this case, the reference voltage is also transmitted by that number. Need to do. In this case, it is equivalent to having a plurality of configurations shown in FIG. 1, and the features are also shown in FIG.

[0036]

As described above, according to the present invention, in the transmission side circuit, each output drive circuit drives the corresponding signal line according to the input signal, and the reference voltage generation circuit causes each output drive circuit to operate. Generates a reference voltage having a predetermined voltage relationship with the signal voltage from and outputs to one signal line, and in the receiving side circuit, each voltage comparator has a reference voltage from one signal line,
Since the signal input to the corresponding output drive circuit is reproduced by comparing it with the signal voltage from the signal line connected to the corresponding output drive circuit, multiple signals are hardly affected by noise. It is possible to transmit and receive between the transmitting side circuit and the receiving side circuit in parallel with a small number of signal lines.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

[Explanation of symbols]

1 ... Transmission side circuit, 2 ... Reception side circuit, 3 ... Reference voltage generation circuit, 4-7 ... Output drive circuit, 8-11 ... Voltage comparator, 2
2 to 26 ... Signal lines.

Claims (1)

[Claims] 1. A signal transfer circuit for transferring a plurality of signals in parallel between a transmission side circuit and a reception side circuit connected by a plurality of signal lines, wherein the transmission side circuit and the reception side circuit are exchanged. The number of signals is one more than the number of signals to be connected, and a plurality of output drive circuits corresponding to the number of signals that drive the signal lines according to input signals are connected to the transmission side circuit, A reference voltage generating circuit for generating a reference voltage having a predetermined voltage relationship with a signal voltage and outputting the reference voltage to one of the signal lines is provided, and the reference voltage from one of the signal lines is provided in the reception side circuit, 2. A signal transfer circuit, characterized in that a number of voltage comparators for comparing a signal voltage from the signal line connected to the corresponding output drive circuit are provided in a number corresponding to the number of signals.