JPS6080347A - Data reception circuit - Google Patents

Abstract

PURPOSE:To regenerate a pulse equal to an initial data pulse by compressing the amplitude of a reception data at a nonlinear amplitude compression circuit to prevent a data pulse from being limited. CONSTITUTION:A data signal is received by a photodetector 6 and outputted from an AMP7. The received data F is subject to amplitude compression to have an amplitude ratio m/n by an amplitude compression circuit 12 and goes to a waveform G. A threshold value curve shown in (16)-3 is shaped from the received data G by an automatic threshold value circuit 13. The 1st threshold value identifying the vicinity of a leading point (16)-1 of the received data signal G is shaped from the curve (16)-3 and the 2nd threshold value identifying the vicinity of a falling point (16)-2 of the signal G is shaped. The 1st and 2nd threshold values identify the signal G at an identification circuit 9 to regenerate the initial data signal having a pulse width TO shown in H.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a receiving circuit such as an original data link, and the essence is data pulse regeneration by suppressing pulse width fluctuations of received data having a wide dynamic range. This invention relates to a data receiving circuit that faithfully performs data receiving.

(b) Conventional technology and problems An example of a conventional original data receiving circuit will be described below.

FIG. 1 shows an optical data receiving circuit of a conventional optical data link. In the figure, 1 is the original data transmitting device, 2 is the original data transmitting circuit, 3 is the original fiber, 3-1 is the tip of the original fiber, 4 is the optical data receiving device, 5 is the optical data receiving circuit, 6 is the light receiving element, 7 is an amplifier (hereinafter referred to as AMP), 8 is an automatic threshold circuit (hereinafter referred to as ATC), 9 is an identification circuit, and 10 is an output terminal. (A) to (E) in the truncated diagram indicate the positions of the waveforms in FIG. 2.

Figures 2 (A) to (E) are for explaining the data link receiving circuit of Figure 1! Showing the waveform of yuzu. The figure (A) shows a data signal with a pulse width TO, which is an initial data pulse. Figure (b) shows the received data signal via the transmission path, with the peak value v
The threshold value is set at 1/2 of O·VO. Figure (c)
The reproducing pulse that reproduces the waveform in Figure (B) at the point of threshold 1/2・■0, in the figure) -1 indicates the case where the amplitude of the above waveform is large, and in) -2 indicates the waveform) - 1 is the limiter waveform limited by AMP, the figure (e) is the peak value V of -2
1/2 of. The data pulse identified by the threshold value of V has a pulse width wider than the original waveform (A) by Δt.

In the source data link shown in FIG. 1, a data signal with a pulse width TO shown in FIG. 1 to the light receiving element 6, and the second
It is converted into a data signal as shown in Figure (b). The data signal passes through the AMP 7 and is generated by the ATC 8. At a threshold value of 1/2 of the wave height 0 as shown in FIG.
It is identified by the identification circuit 9 and reproduced into a data pulse having the same waveform as the initial data signal of pulse width To as shown in FIG. 2(C). Since the above data signal (b) tends to have the same rise and fall characteristics, it can be reproduced into a pulse with the initial pulse width TO by identifying it with a value that is 1/2L# of the peak value VO.

However, when the received data has a wide dynamic range and the level of the received data is high < AMP7, the data signal is saturated as shown in Figure 2)-1 during the amplification process of AMP7, and due to this saturation, the data signal is limited by AMP7. Therefore, the waveform becomes )-1 and the limiter waveform becomes )-2.

The above IJ mitter waveform)-2 is the saturation waveform)-1
Since the upper level part of the peak value of the pulse is limited, the part that indicates the phase of the falling point of the data with the initial data signal is limited, so the tendency of the characteristics of the rising and falling edges of the pulse is different. II It is not possible to reproduce the initial pulse from the Mitter waveform.

That is, for this limiter waveform, a threshold value of 1/2 of the peak value V of -2 is created by the ATC 8, and at this threshold value V 100, the identification circuit 9 identifies -2 for the limiter waveform. Then, the pulse width T 1 (=TO + △t) shown in Fig. 2 (e)
data pulses are regenerated. This data pulse (E)
The pulse width is wider by Δt than the initial data pulse.

Normally, the pulse width variation in data transmission equipment is ±lO%
Since a value of the following order is required, the receiving circuit as described above has the disadvantage that the dynamic range of the input signal level is small.

(c) Object of the Invention In order to solve the above-mentioned drawbacks, the present invention provides an original data receiving circuit that reproduces pulses equal to initial data pulses by compressing the amplitude of received data using a nonlinear amplitude compression circuit. The purpose is to

(d) Structure of the Invention In order to achieve the above-mentioned object, a received data signal is identified by a threshold value determined by an automatic threshold adjustment circuit, and an output circuit of a differential amplifier is used in the original data receiving circuit. A nonlinear amplitude compression circuit configured by inserting a diode and a resistor into the circuit, and a first threshold value that determines the rise of a data pulse output from the circuit, and a second threshold value that determines the fall of the pulse, respectively, are shaped. The present invention is characterized in that it includes an automatic threshold adjustment circuit and an identification circuit that identifies the received data signal using the first and second thresholds.

(e) Embodiments of the invention The present invention compresses received data using a non-linear amplitude compression circuit,
A data receiving circuit that identifies compressed data using the first and second thresholds, the first and second thresholds being provided near the rising and falling points of the compressed data, respectively. It is.

Hereinafter, the original data receiving circuit of the present invention will be explained based on the drawings. FIG. 3(a) is a block diagram of an embodiment of the optical data receiving circuit of the present invention. In the figure, 3 to 10 indicate the same members as in FIG. 1, 11 is an optical data receiving circuit, 12 is a nonlinear amplitude compression circuit, and 13 is an ATC.

FIG. 3(b) shows the characteristics of the threshold value shaped by ATC.

FIG. 4 shows the output characteristics of the nonlinear amplitude compression circuit (hereinafter referred to as amplitude compression circuit) 12, where characteristic A shows a nonlinear characteristic and becomes a broken line characteristic at the input signal level v1-1. There is. Characteristic B shows an assumption when this line 12 has linear characteristics.

FIGS. 5(f) to (a) show waveforms at each point in FIG. 3. FIG. 5(f) shows the received waveform, FIG. 1(g) shows the output waveform of the amplitude compression circuit 12, and FIG.

FIG. 3 will be explained using FIGS. 4 and 5.

In FIG. 3, similarly to the data signal shown in FIG. 1, a data signal having a pulse width TO shown in FIG.

This data signal becomes as shown at the source fiber 3-source fiber tip. This received data (to) is sent to the amplitude compression circuit 12
Input signals Vi-1 to Vi-4 as shown in FIG.
The amplitude is compressed to the amplitude ratio m/n in the range of
Obtain the waveform shown in (g). Here mln is the input signal V
The amplitude values of broken line A and straight line B at i-4 are shown. In the figure,
The part indicated by the dotted line is the input Campbell Vi-10 of the same circuit 12.
In the output waveform for -1, 0-2, the falling characteristic between the falling point @-2 and the point ○-2 in figure (G) is at the level of the dotted line,
The waveform changes to a broken line characteristic and is compressed into a waveform corresponding to the imaging width pressure wl characteristic of A characteristic [phase]-1 to [phase]-2 in FIG.

The compressed received data (g) is input to the ATC 13 and the identification circuit 9, respectively.

At ATC13, from the received data ■, Fig. 5 [phase] -
The threshold curve shown in 3 is shaped. From this curve O-3, the first threshold value that identifies the vicinity of the rising point [phase] -1 of the received data signal ■ is shaped, and the first threshold that identifies the vicinity of the falling point [phase] -2 of the received data signal ■ is shaped. A second threshold value is shaped.

The first of these. As for the second threshold, the identification circuit 9 identifies the received data signal (2) and reproduces the initial data signal having the data pulse shown in FIG. 5(g); pulse width TO.

Here, even if the pulse is identified by providing a threshold value at the rising point [phase] -1 of the data signal (1) and its vicinity, the same pulse as the initial pulse can be obtained.

Note that the ATC 13 is configured as follows. In a circuit for shaping a received data signal pulse to create a threshold, the received data signal pulse is input to an identification circuit and an integrating circuit, and the output of the integrating circuit is input to a level shift circuit to create a first threshold. providing means for shaping the value; providing means for inputting the first threshold value to the identification circuit to identify a rising edge of the received data signal pulse; and providing means for driving a constant current control circuit with the output of the identification circuit; Means is provided for inputting the constant current output from the constant current control circuit to the level shift circuit to shape the first threshold value into a second threshold value, and the second threshold value is input to the identification circuit. The method is characterized in that a falling edge of the input pulse is identified.

FIG. 6 is a block diagram of an embodiment of the amplitude compression circuit 12 of the present invention. In the figure, R1-R4 are resistors, Dl is a diode, and T
RI and TR2 are transistors, 18 is a constant current source, 19 is input data (see Figure 5), 20 is output data (
5 (g)), vl is the input signal, Vout is the output signal, Vcc is the power supply, Vref is the reference voltage, VB2
．． VH2 indicates voltage. FIG. 7 shows the input and output compression characteristics of the amplitude compression circuit of FIG. 6. In the figure, the characteristic VR2 at the point of input level Vj-1 shows the voltage drop of the resistor R2, and after that, the characteristic of the diode D1 is added and curved, and after Vi-2, it is due to the combined resistance of the diode D1 and the resistor R2. It's in a straight line.

The characteristic VR3 is due to the voltage drop across the resistor R3.

The operation of FIG. 6 will be described using the characteristics of FIG. 7. In FIG. 6, input data Vi is input to the base of transistor TRI, and if reference voltage Vref is set to a required value, input data Vt is output to the collector of transistor TRI as Vout. In this case, when the input data level is in the range of Vi-1, the diode D
1 is not conducting, the characteristic of VB2 in Figure 7 becomes linear, and when the input level exceeds Vi-1, the diode D
1 operates, its characteristics exhibit a curve as shown in the figure, and thereafter become a straight line. Vout is Vout=VR2+VR3
made by.

Next, the output data characteristic Vout is calculated from the following equation.

Vout = VB2-+VR3 - current in D1, Ic is collector current of transistor TRO, Vref is reference voltage and bias voltage of transistor TRI, q is charge °, k is Boltzmann constant, T is saturation current of diode Dl, IO is Indicates the constant current of a constant power supply.

FIG. 8 shows another embodiment of the present invention. In the figure, the same numbers and symbols as in FIG. 6 indicate the same members. R5゜R6 is resistance, D
2 indicates a diode.

Figure 9 shows the person and output characteristics of Figure 8. FIG. 8 will be explained using FIG. 9.

In FIG. 8, diodes DI are connected in parallel.

Diode D2 connected in parallel with resistor R2. A resistor R3 is connected in series and connected in series to the collector of the transistor TRI. At input data signal voltage Vi-1, diode D1
is turned on, the output characteristic becomes the first broken line characteristic at point A shown in FIG. 9, and then the input data signal voltage Vi-2
Diode D2 turns ON at , and the output characteristics become the second broken line characteristic at point -1'OB shown at point B in Figure 9. In this way, the output characteristics change depending on the number of diodes. A break point f can be created at

Due to these multiple broken line characteristics, the compression characteristics of the amplitude compression circuit can be relaxed, so the increase in pulse width with respect to the threshold value can be suppressed to a small value, and the pulse width TO of the reproduced data pulse can be changed to the pulse width of the initial data pulse. This has the advantage that the width can be more closely approximated than when using only one diode.

(f) Effects of the Invention According to the present invention, in the data receiving circuit, by using a non-linear amplitude compression circuit for the pulse waveform of received data having a wide dynamic range, it is possible to prevent the data pulse from being limited by a limiter. The output data of the amplitude compression circuit is identified and reproduced using the first threshold value at the rising point and the second threshold value at the falling point of the output data pulse of the non-linear amplitude compression circuit to determine the pulse width. It has the advantage of being able to suppress fluctuations to a minute level and reproducing faithful data pulses.

[Brief explanation of the drawing]

FIG. 1 shows a conventional original data link receiving circuit, FIG. 2 shows various waveforms shown in FIG. 1, FIG. 3 shows an overview of the present invention, and FIG.
The figure shows the amplitude compression characteristics, Figure 5 shows the waveform at each point in Figure 3, and Figure 6 shows the waveform at each point in Figure 3.
7 is an operating characteristic diagram of FIG. 6, FIG. 8 is another amplitude compression iol path of the present invention, FIG. 9 is a tip of the operating characteristic diagram of FIG. Original data receiving device, 5 is an optical data receiving circuit, 6 is a light receiving element, 7 is an amplifier, 8 is A
TC19 is an identification circuit, 10 is an output terminal, 11 is an optical data receiving circuit, 12 is an amplitude compression circuit, 13 is ATC1■-1
, 4)-2 is the output waveform for input level V i -1, ■-1, [phase]-2 is the characteristic range of the broken line, o-1 of the waveform (G) is the rising point, o- of the waveform (G) 2 is falling, o-
1 is the rising point of the waveform (to), O-2 is the falling point of the waveform (to), 18 is a constant current source, 19 is an input signal, and 20 is an output signal. 1 (intestine\J-) L 0 (Figure 6) Figure 7 Figure VLIVi-I Vi Figure B Figure 9

Claims (1)

[Claims] In a data receiving circuit in which a received data signal is identified by a threshold value shaped by an automatic threshold adjustment circuit, a diode and a resistor are inserted in the output circuit of a differential amplifier to which the received data signal is input. a first threshold value for identifying a rising edge of a pulse of the received data signal output from the non-linear amplitude compression circuit; and a second threshold value for identifying a falling edge of the received data signal pulse. and an identification circuit that identifies the received data signal using first and second threshold values output from the automatic threshold adjustment circuit.