JPS5875947A - Response delay correcting device for optical communication - Google Patents

Abstract

PURPOSE:To correct response delay by connecting plural trigger circuits which have different response speeds to a photodetector, and synthesizing outputs of those trigger circuits. CONSTITUTION:When an optical pulse wave is inputted to a phototransistor 10, the phototransistor 10 turns on and off in response to the input pulses to vary and apply the terminal voltage across a resistance 11 to trigger circuits 2 and 4. The trigger circuits 2 and 4 detect and output the leading and trailing edges of the input signal, but capacitors 12 and 16 differ in capacity; the 1st trigger circuit 2 allows a signal of relatively low frequency to pass and to be amplified by an inverter 13, and the 2nd trigger circuit 4 allows a signal of relatively high frequency to pass and to be amplified by an inverter 17. The output of both trigger circuits 2 and 4 are synthesized and applied to a Schmitt trigger circuit 3 for waveform shaping, thus obtaining nearly the same waveform as the input signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a response delay correction device used in optical communication, which is capable of correcting a light receiving element having a slow response speed so that it can be used up to a relatively high frequency.

In optical communication, a light wave modulated into pulses is converted into an electrical signal by a light receiving element, and various data, video signals, etc. can be communicated using this electrical signal. The frequency that can be communicated with this optical communication (the speed that the 9L light receiving element can convert)
The millimeter was decided, and there was a limit naturally.

FIG. 1 shows a conventional configuration, in which the light receiving element 1 has 1 to
A trigger circuit 2 is connected to the trigger circuit 2, and a Schmitt trigger circuit 3 is connected to the trigger circuit 2, and the outputs of the trigger circuits 1 to 3 are shaped into the output waveform of the light receiving element. In this conventional configuration, waveforms at various parts when a relatively high frequency optical pulse wave is input to the light receiving element 1 are shown in FIG. Due to the response delay of 1, the falling edge is completely 0.
Since it does not fall to the level,
The waveform at output point B (at the output point B) cannot be inverted, and the
It is no longer possible to output a pulse wave with the same frequency as the optical pulse wave input to the . This results in a malfunction in which the high level state is maintained while the signal is being input.

In view of the drawbacks of the above, the present invention connects a plurality of trigger circuits to the light receiving element and combines the outputs of each trigger circuit to emphasize the rising and falling parts of the signal from the light receiving element. An object of the present invention is to provide a response delay correction device for optical communications which can be used up to a high frequency range by correcting response delays.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of this embodiment. Another second trigger circuit 4 is connected in parallel to the trigger circuit 2, and the response frequency of this second trigger circuit 4 is The first trigger circuit 2 is set as high as 7. Figure 3 is the second
This shows the specific electric circuit in the figure, where the light receiving element 1
The photo transistor 10 and the resistor 11 are connected in series, one end of the resistor 11 is grounded, and a positive potential is connected to the resistor of the first transistor 10.

The emitter of the phototransistor 10 has the first and second
Trigger circuits 2 and 4 are connected, and both 1 and 2 trigger circuits are connected.
゜4 both have the same configuration and both have a capacitor of 12.1G
, an inverter 13.17, and a resistor 14.18 are connected in series, and a resistor 1! is connected across the inverter 13.17. i, 1
9 are connected in parallel. The constants of each member constituting the first and second trigger circuits 2.4 are 0.2 μF for capacitor 12, 200 pF for capacitor 16,
The resistor 14 is 22Ω, the resistor 18 is 101Ω, and the resistor 15.
19 are each 1 MO, and the second trigger circuit 4 has a characteristic that it is easier to pass a higher frequency than the first trigger circuit 2. Resistance 14. '18 is 1-Riga circuit 2
, 4, an inverter 20 is connected to both resistors 14 and 18, a resistor 21 is connected in parallel to the inverter 20, and a resistor 22 is connected to the output side of the inverter 20. . The resistor 22 is the Schmidt 1~
The Schmitts 1 trigger circuit 3 consists of an inverter 23, 24 and a resistor 25. The inverters 23, 24 are connected in series, and the resistor 25 is connected to the input side of the inverter 23 and the output side of the inverter 24. connected in parallel. The output of this inverter 24 is a waveform-shaped output.

Next, the operation of this embodiment will be explained.

When an optical pulse wave enters F A1 to transistor 10, F A1 to transistor 10 turn A in response to the pulse.

turns on, changes the terminal voltage of resistor 11, and trigger circuit 2
．． Skip inputting to 4. The trigger circuits 2 and 4 T detect and output the rising and falling edges of the input signal, respectively, but since the capacitors 12 and 16 have different capacities, the first
In the trigger circuit 2, relatively low frequency signals are passed through and amplified by the inverter 13, and in the second trigger circuit 4, relatively high frequency signals are amplified by the inverter 17 while being passed through. The outputs of both trigger circuits 2 and 4 are combined, amplified by an inverter 20, and input to the Schmitt trigger circuit 3 via a resistor 22. The Schmitt 1 to trigger circuits 3 shape the waveform of the input signal, and output the phototransistor. A pulse signal that is almost the same as the optical pulse wave input to 10 is output.

Here, the waveform at the output point C of the second trigger circuit 4 is changed to the output point of the inverter 20 by d1, and the waveform at the output point E of the trigger circuit 3 is e.
When each waveform is shown in FIG. 5, the output waveform C of the trigger circuit 4 changes sharply at the rising and falling edges of the input signal, and the output of the second trigger circuit 5 and the first] ~D that combines the outputs of Riga circuit 2
The waveform d at point is close to the signal input to the phototransistor 10, and the Schmidts 1-trigger circuit 3 can shape this waveform and output an accurate pulse wave as shown in waveform e.

Since the present invention is configured as described above, by emphasizing the rising edge and falling edge of the signal waveform from the light receiving element using a plurality of 1-trigger circuits, the delay of the light receiving element having a slow response speed can be corrected. The apparent response speed can be increased and it can be used up to a high frequency range.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of conventional optical communication.
The figure is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a specific electric circuit diagram of the same as above, FIG. 4 is a waveform diagram showing waveforms of various parts in the conventional configuration, and FIG. In the example (
FIG. 1... Light receiving element, 2.4... Trigger circuit, 3...
C: L mitsu trigger circuit. 6-

Claims (1)

[Claims] Consisting of a light-receiving element that converts an optical signal into an electrical signal, a plurality of 1-trigger circuits connected to the light-receiving element, and a trigger circuit that inputs the output signal of each trigger circuit, The response speed of each trigger circuit is set to be relatively high or relatively slow, and the signal that synthesizes the outputs of each trigger circuit is
:Response delay correction circuit for optical communication, characterized by driving a Rishmi 1-1-Riga circuit.