JPS62180643A - Pulse transmission system - Google Patents

Abstract

PURPOSE:To prevent the change in delay time and the deterioration in noise margin due to ground potential difference between the sending side and receiving side at pulse signal transmission by generating both a signal pulse and its comparison potential at the transmission side and sending them to the reception side. CONSTITUTION:A pulse signal is sent in the order of points A, B and C through a unipolar amplifier of an ECL circuit both for transmission and reception. In the transmission, a comparison potential Vref is sent with respect to a ground in addition to the pulse signal. The sent pulse signal and the potential Vref are terminated by a resistor RT. As the resistor RT, a resistor having the same resistance as the impedance of the transmission line is used. The ECL circuit is a circuit switched depending on whether the potential of an input signal is higher or lower then the level of the signal Vref and the reference in considering the delay time is a point of time when the signal passes through the level Vref. Since the signal Vref being the reference of the delay time is sent by the same condition as the signal, the effect of ground potential difference between the transmission and reception is not given and since a common mode noise is given to the same condition between the signal and the level Vref, the effect of improving the noise margin is given.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pulse transmission system suitable for pulse transmission 10 in ECL and CML circuits.

[Background of the invention]

Conventionally, the pulse transmission of ECL and CML circuits transmitted only the pulse signal along with the graphite.6 However,
If there is a difference of 15 in the graphite potential between the transmitting and receiving sides, the signal comparison potential changes by this potential.

As shown in Figure 3, the receiving side.

The signal changes ('H' level → %L# level, 1L#.

The time to detect the bell→ant Hl level) changes. .

This is because the delay time from the sending side changes 520.

In Figure 3, the signal is transmitted in the order of point A, point B, and point 0.
The waveform at the point is the ground voltage on the sending and receiving side.

When the potential difference ΔV is 0 [v], let it be C: x [v].

becomes Cx. At this time, a time difference △tpd is generated from the bridge number change time at point B and the comparison potential difference (X (V:))'.

do. In other words, when the comparison potential is normal (ΔV=O(Vl)
.

The delay time changes by Δtpd from the delay time tpd.

That's what I did.

This is especially true when transmitting the same type of signal to four receiving points, there will be a difference in signal reception time between each receiving point.

I have to do this, and there are a lot of problems.

Also, the comparison potential changes, which causes noise in the transmission system.

Conventionally, as a countermeasure for six small songs with lower margins, three lines were transmitted: the bipolar output of the 15 transmitter and the brush l-'' as shown in Figure 4. The signal line of Hinoki was transmitted.

This is difficult to achieve when the number of signals to be transmitted increases. ' For example, regarding conventional transmission, see 1977n Fairchild Camera and Instrument Corporation E.L.D.

-Ta Pukuku 5-21 Noise 5-22 (1977'
Fairchild Camera and Instrument
rument CorporationECL DA
TA BOOK5-21 Ftg5''-22).

[Purpose of the invention]

An object of the present invention is to provide a transmission side during pulse signal transmission.

It is an object of the present invention to provide a pulse transmission system 10 that prevents changes in delay time and reduction in noise margin due to ground potential differences on the receiving side.

[Summary of the invention]

The present invention solves the problem of the conventional problem of ground potential difference.
Focusing on the fact that when the comparison potential on the receiving side changes, the cause of v5 is that the reference point when creating the signal pulse (transmitting side ground 15) and the reference point for the comparison potential (receiving side ground) are different. Make the reference potential reference on the receiving side the same as the reference on the transmitting side.

It is possible to eliminate the effects of ground potential differences by creating signals and comparing voltages with respect to the same reference potential for both transmission and reception.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Fig. 1 is a diagram corresponding to Fig. 3 showing a conventional example, and the difference is that the reference power supply Vref for signal generation is only on the transmitting side, and the receiving side uses Vref of the transmitting side. Figure 1 is described using an actual circuit.

It is.

In this embodiment, both transmission and reception are performed using homopolar 10-polarity amplifiers of ECL circuits, and pulse signals are transmitted in the order of A point, B point, and 0 point.

In addition to the pulse signal, the transmission uses the comparison potential Vref and graph.

perform the command.

The transmitted pulse signal and Vref are RTIF on the receiving side.
.

terminated by This RT uses a resistor with the same value as the impedance of the transmission line.

The ECL circuit uses a known method (input signal for vref).

It is a circuit that switches depending on whether the potential of the signal is high or low, and when considering the delay time, the criteria are 8・(), 4
.

This is the time when the signal passes through Vref.

In this embodiment, Vref', which is the reference for this delay time, is transmitted under the same conditions as the signal, so it is not affected by the ground potential difference between transmitting and receiving, and is common.

For mode noise, noise often appears on the signal and Vref under the same condition 5, so noise merge is performed.

It has the effect of responding to people's needs.

〔Effect of the invention〕

According to the present invention, the influence of the ground potential difference in the transmission system on the delay time can be ignored, and the noise margin against common mode noise can be widened.

This allows highly accurate signal transmission with a wide noise margin.

[Brief explanation of drawings]

FIG. 1 is a transmission conceptual diagram of an embodiment of the present invention, FIG. 152 is a circuit diagram of the same embodiment, FIG. 5 is a conventional transmission conceptual diagram, and FIG. 4 is a conventional bipolar transmission diagram. Ru.

Claims (1)

[Claims] 1. When performing pulse transmission, a pulse transmission method is characterized in that both a signal pulse and its comparison potential are created on the transmitting side, and both are transmitted to the receiving side.