JPH11261482A - Bursted light reception circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bursted light reception circuit which automatically detects rising of a burst signal and can appropriately suppress an offset that fluctuates every burst. SOLUTION: In a burst optical reception circuit, a comparator 11 has a positive phase signal peak output signal (c) of a positive phase peak value detection circuit 10 monitor a peak value of a positive phase signal (a) of an input burst signal, detects that the next input burst signal is inputted when the peak value exceeds a specified voltage value, and transmits a comparison signal to the effect that a reset signal generation circuit 12 is made to generate a reset signal (e). In this case, the reset signal generation circuit 12 transmits the reset signal (e) to a reversed phase peak value detection circuit 6 and, when the reset signal (e) is inputted, the reversed phase peak value detection circuit 6 begins to detect the peak value of the reversed phase signal (b) in the next input burst signal. Thus, the offset every burst is automatically detected and suppressed without a control signal from outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a PDS (Passive Double Sta
r) It relates to a burst light receiving circuit applied to a system or the like.

[0002]

2. Description of the Related Art Conventionally, as a PDS system for transmitting and receiving this kind of burst optical signal, for example, a PDS system as shown in FIG. In this PDS system, burst optical signals of a plurality of subscriber stations (ONUs 1 to 3) are respectively divided into burst data BD1 by time division multiplexing.
３3 are transmitted to the station 13 in the upward direction.

In the case of this PDS system, burst data BD1 to 3 of burst optical signals received by the station 13
Must be received as optical signals having different amplitudes for each burst. Also, the optical transmitter provided in each subscriber station has a different extinction ratio (power ratio between 1 level and 0 level) due to a difference in the setting of the bias current of the light emitting diode (LD). For example, as shown in the burst data BD1 and BD2 in FIG. 5, the 0 level varies for each burst.

In general, an optical receiving circuit provided on the side of the station 13 has a direct-current (DC) coupling type configuration in many cases in order to receive a burst optical signal including such burst data BD1 to BD3. However, in the DC-coupled optical receiving circuit, the 0 level of the input burst optical signal, that is,
When the offset level fluctuates, an identification error occurs, which causes serious degradation in reception sensitivity.

Therefore, as a burst light receiving circuit applied to the optical receiving circuit on the side of the station 13 and compensating for such offset level fluctuation, for example, disclosed in Japanese Patent Application Laid-Open No. 8-256119, supplied from the outside. The peak detection circuit is reset by the received control signal, and the offset of the next burst signal is detected.

Other known techniques related to burst light reception include, for example, a burst light receiving circuit disclosed in Japanese Patent Application Laid-Open No. 8-102716 and Japanese Patent Application Laid-Open No. 8-33310.
Patent Document 64, a receiving circuit, an optical receiving circuit, an optical receiving module, and an optical wiring module set.
And a burst digital optical receiver disclosed in Japanese Patent No. 81687.

[0007]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Hei 8-2
In the case of the burst light receiving circuit disclosed in Japanese Patent No. 56119, the peak detection circuit is reset by an external control signal to detect the offset of the next burst signal. However, in an actual PDS system, reception is performed on the station side. Since each burst signal has a delay variation of about ± 2 bits, there is a problem that it is difficult to predict an accurate timing indicating the start of the burst.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and its technical problem is to automatically detect a rising edge of a burst signal and appropriately suppress an offset that varies for each burst. It is an object of the present invention to provide a burst light receiving circuit that can obtain the same.

[0009]

According to the present invention, there is provided a DC optical system which receives a burst optical signal containing burst data from the outside and converts the received burst optical signal into an electric signal and inputs it as an input burst signal.
In a coupled-type burst optical receiving circuit, a first differential amplifier that differentially amplifies an input burst signal and outputs a positive-phase signal and a negative-phase signal, and detects a peak value of the positive-phase signal to output a positive-phase signal A positive-phase peak value detection circuit that outputs a peak output signal, a negative-phase peak value detection circuit that detects a peak value of a negative-phase signal and outputs a negative-phase signal peak output signal, and a positive-phase signal peak output signal A comparator that outputs a comparison signal indicating a result of comparison with a reference voltage having a predetermined voltage value, and generates and outputs a reset signal that resets the peak value detection circuit for reverse phase when the comparison signal exceeds a predetermined voltage value. A burst light receiving circuit including a reset signal generating circuit is obtained.

Further, according to the present invention, in the above burst optical receiving circuit, a preamplifier for current / voltage conversion of an input burst signal and outputting a burst output signal is provided, and the first differential amplifier performs differential amplification processing. As a result, a burst light receiving circuit that differentially amplifies a burst output signal and outputs a positive-phase signal and a negative-phase signal is obtained.

Further, according to the present invention, in any of the above burst light receiving circuits, an average value detecting circuit for detecting an average value of the positive-phase signal and the negative-phase signal and outputting an average value detection signal; A burst light receiving circuit including a second differential amplifier that differentially amplifies a voltage corresponding to the voltage value difference between the detection signal and the negative-phase signal peak output signal and outputs an applied voltage signal is obtained.

In addition, according to the present invention, in the above burst light receiving circuit, the emitter side is grounded via the resistor, and the collector side is connected to the collector side based on the potential of the applied voltage signal applied to the base side. A burst light receiving circuit including a transistor for controlling an input current is obtained.

According to the present invention, in any one of the above-described burst light receiving circuits, a difference between a light receiving element for receiving a burst light signal, converting the signal into an electric signal and outputting an input burst signal, and a burst output signal is provided. A burst light receiving circuit including an identification circuit that identifies a moving value and outputs a reception output signal is obtained.

On the other hand, according to the present invention, a PDS system comprising a station equipped with the above-mentioned burst optical receiving circuit and a plurality of subscriber stations for transmitting a burst optical signal by changing the amplitude of each burst so as to be different. Is obtained.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a circuit block diagram showing a basic configuration of a burst light receiving circuit according to one embodiment of the present invention.

The burst light receiving circuit includes: a light receiving element 1 for receiving a burst light signal including burst data from outside and outputting an input burst signal converted into an electric signal;
A preamplifier 2 for current / voltage conversion of an input burst signal to output a burst output signal, an identification circuit 3 for identifying a differential value of the burst output signal and outputting a received output signal, and a differential amplification process for the input burst signal A first differential amplifier 4 for differentially amplifying a burst output signal to output a positive-phase signal a and a negative-phase signal b, and detecting an average value of the positive-phase signal a and the negative-phase signal b to detect an average value An average value detection circuit 5 for outputting the signal f, a negative phase peak value detection circuit 6 for detecting the peak value of the negative phase signal b and outputting a negative phase signal peak output signal g;
A second differential amplifier 7 for differentially amplifying a voltage corresponding to the difference between the voltage value of the average value detection signal f and the voltage value of the negative-phase signal peak output signal g and outputting an applied voltage signal h;
And a transistor 8 that controls the input current of the preamplifier 2 on the collector side based on the potential of the applied voltage signal h applied to the base side.

Also, in the case of this burst light receiving circuit, the peak value of the positive-phase signal a is detected and the positive-phase signal peak output signal c is detected.
, And a reference voltage (Vref) d having a predetermined voltage value applied to the negative-phase input terminal and a positive-phase signal peak output signal c input from the positive-phase input terminal. A comparator (comparator) 11 that outputs a comparison signal indicating a result of the comparison, and a reset signal e that resets the negative-phase peak value detection circuit 6 when the comparison signal exceeds a predetermined voltage value and goes high. A reset signal generating circuit 12 for generating and outputting.

That is, in this burst light receiving circuit,
The comparator 11 monitors the peak value of the positive-phase signal a of the input burst signal based on the positive-phase signal peak output signal c from the positive-phase peak value detection circuit 10, and when the peak value exceeds a predetermined voltage value, the next And outputs a comparison signal to the reset signal generation circuit 12 to generate a reset signal e. In such a case, the reset signal generation circuit 12 sends the reset signal e to the peak value detection circuit 6 for reverse phase, and when the reset signal e is input to the peak value detection circuit 6 for reverse phase, the reverse signal in the next input burst signal is input. The detection of the peak value of the phase signal b starts. In this way, the function of automatically detecting the offset for each burst without an external control signal, and automatically detecting and suppressing the offset level that changes for each burst causing an error in the DC-coupled circuit. Offset compensation can be performed.

As described with reference to FIG. 4, such a burst optical receiving circuit is provided in a station and has a plurality of subscribers that transmit a burst optical signal while changing the burst optical signal so that the amplitude differs for each burst. It is constructed as a PDS system in combination with a remote station.

FIG. 2 is a timing chart showing an example of a signal processing waveform of each part in the burst light receiving circuit. FIG. 2A shows a positive-phase signal a and a negative-phase signal a from the first differential amplifier 4. FIG. 4B shows a signal b of the positive-phase signal from the positive-phase peak value detection circuit 10.
FIG. 3C shows the reset signal generation circuit 12.
FIG. 6D shows the reset signal e from FIG. 5A, and FIG. 6D shows the reset signal e from the average value detection circuit 5 and the reverse phase signal peak output signal g from the reverse phase peak value detection circuit 6. e) relates to the applied voltage signal h from the second differential amplifier 7, and FIG.
And the negative-phase signal b 'and the negative-phase signal b' whose offset has been compensated.

In the case of the operation processing of the burst light receiving circuit, as shown in FIG. 2A, it is assumed that the positive-phase signal a and the negative-phase signal b output from the first differential amplifier 4 are interposed. If it is assumed that the offset level Vos exists for the 0 level V0, the positive-phase signal peak output signal c in the positive-phase peak value detection circuit 10 becomes the reference voltage d as shown in FIG. Higher. Therefore, the reset signal generating circuit 12 generates and outputs a reset signal e as shown in FIG. 2C at the moment when the positive-phase signal peak output signal c becomes higher than the reference voltage d. Incidentally, in the positive phase peak value detection circuit 10, the reference voltage d is set to a voltage value sufficient to detect the head of the burst.

Next, in this state, when a reset is applied by the reset signal e, the anti-phase peak value detection circuit 6 detects the next peak value of the anti-phase signal b, as shown in FIG.
As shown in (d), the signal is output as an inverted-phase signal peak output signal g. Therefore, when the next burst optical signal is input, the level of the next burst optical signal is 0 (that is, the reverse phase signal b).
1 level). At this time, the average value detection circuit 5 outputs the result of detecting the average value of the positive phase signal a and the negative phase signal b as an average value detection signal f, as shown in FIG. 2D.

Further, the second differential amplifier 7 differentially amplifies a voltage corresponding to the difference between the voltage values of the average value detection signal f and the negative-phase signal peak output signal g, as shown in FIG. Thus, the applied voltage signal h is transmitted and output to the base side of the transistor 8. As a result, the transistor 8 to which the applied voltage signal h is applied controls the input current of the preamplifier 2 by causing a current to flow from the light receiving element 1 toward the resistor 9 on the emitter side, and the burst output from the preamplifier 2 is controlled by this control. As a result of suppressing the offset level Vos of the signal,
As shown in FIG. 2F, the offset-compensated positive-phase signal a ′ and negative-phase signal b ′ from the first differential amplifier 4 are obtained.

FIG. 3 is a timing chart showing another example of the signal processing waveform of each part in the burst light receiving circuit. The signals in FIGS. 3A to 3F are the same as those in FIG. ing.

As a prerequisite for the operation processing of the burst light receiving circuit, when applied to a PDS system, the driving current source in the LD driving circuit of the optical transmitter on each subscriber side is turned on / off for each burst, and stable operation is measured. Therefore, a pre-bias current process in which a current starts to flow several bits before the actual burst optical signal may be performed. In such a case, the positive-phase signal a and the negative-phase signal b output from the first differential amplifier 4 are used.
Is the pre-bias component signal p as shown in FIG.
Is obtained.

Even when a burst optical signal including such a pre-bias component signal p is input, reception processing can be performed. That is, in such a case, the positive-phase signal peak output signal c in the positive-phase peak value detection circuit 10 is the signal shown in FIG.
Since the waveform is higher than the reference voltage d as a waveform influenced by the presence of the pre-bias component signal p as shown in FIG. 2B, the reset signal generating circuit 12 outputs the positive-phase signal peak output similarly to the case described with reference to FIG. The reset signal e may be generated and output as shown in FIG. 3C at the moment when the signal c becomes higher than the reference voltage d. When reset by the reset signal e, the negative-phase peak value detection circuit 6 outputs a negative-phase signal peak output signal g that detects one level of the negative-phase signal b. The subsequent operation is the same as that described with reference to FIG.

[0028]

As described above, according to the burst light receiving circuit of the present invention, as a first effect, a function of automatically detecting and suppressing the rise of the burst light signal is provided. There is no need to receive a control signal notifying the start of the burst optical signal from the outside, and there is an advantage that the offset can be simplified and accurately suppressed with a simple configuration.
Further, as a second effect, since the offset compensation is constituted by one transistor, it is possible to simultaneously compensate not only a direct current (DC) offset but also an offset fluctuating for each burst, thereby improving the basic performance. The advantage is that it is improved. Further, as a third effect, since the offset is compensated for each burst, it is possible to receive burst signals from optical transmitters of subscriber stations having different extinction ratios when applied to a PDS system. Therefore, there is an advantage that the basic performance of the PDS system can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a basic configuration of a burst light receiving circuit according to one embodiment of the present invention.

FIG. 2 is a timing chart showing an example of a signal processing waveform of each unit in the burst light receiving circuit shown in FIG. 1, wherein (a) relates to a positive-phase signal and a negative-phase signal from a first differential amplifier; (B) relates to a positive-phase signal peak output signal from a positive-phase peak value detection circuit, (c) relates to a reset signal from a reset signal generation circuit,
(D) relates to the average value detection signal from the average value detection circuit and the negative phase signal peak output signal from the negative phase peak value detection circuit, and (e) relates to the applied voltage signal from the second differential amplifier. , (F) relate to the offset-compensated positive-phase signal and negative-phase signal from the first differential amplifier.

3A and 3B are timing charts showing other examples of signal processing waveforms at various parts in the burst light receiving circuit shown in FIG. 1, wherein FIG. 3A relates to a positive phase signal and a negative phase signal from a first differential amplifier. , (B) relates to the positive phase signal peak output signal from the positive phase peak value detection circuit, (c) relates to the reset signal from the reset signal generation circuit,
(D) relates to the average value detection signal from the average value detection circuit and the negative phase signal peak output signal from the negative phase peak value detection circuit, and (e) relates to the applied voltage signal from the second differential amplifier. , (F) relate to the offset-compensated positive-phase signal and negative-phase signal from the first differential amplifier.

FIG. 4 is a block diagram showing a schematic configuration of a conventional PDS system for transmitting and receiving a burst optical signal.

FIG. 5 is a diagram schematically illustrating a state of a level change of each burst of a burst optical signal (burst data) transmitted by an optical transmitter of each subscriber station provided in the PDS system illustrated in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light receiving element 2 preamplifier 3 identification circuit 4, 7 differential amplifier 5 average value detection circuit 6 negative phase peak value detection circuit 8 transistor 9 resistor 10 positive phase peak value detection circuit 11 comparator (comparator) 12 reset signal generation Circuit 13 Office

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/04 10/06

Claims (6)

[Claims] 1. A DC-coupled burst optical receiving circuit for receiving a burst optical signal including burst data from the outside and converting the burst signal into an electric signal and inputting it as an input burst signal, differentially amplifies the input burst signal. A first differential amplifier that outputs a positive-phase signal and a negative-phase signal, a positive-phase peak value detection circuit that detects a peak value of the positive-phase signal and outputs a positive-phase signal peak output signal, A negative-phase peak value detection circuit that detects a peak value of the phase signal and outputs a negative-phase signal peak output signal, and a comparison signal indicating a result of comparing the positive-phase signal peak output signal with a reference voltage having a predetermined voltage value And a reset signal generation circuit for generating and outputting a reset signal for resetting the negative phase peak value detection circuit when the comparison signal exceeds a predetermined voltage value. A burst light receiving circuit characterized by the above-mentioned. 2. The burst optical receiving circuit according to claim 1, further comprising a preamplifier for converting the input burst signal into a current and a voltage to output a burst output signal, wherein the first differential amplifier is configured to perform the differential amplification. A burst light receiving circuit for differentially amplifying the burst output signal and outputting the positive-phase signal and the negative-phase signal as processing. 3. The burst light receiving circuit according to claim 1, wherein an average value detection circuit that detects an average value of the positive-phase signal and the negative-phase signal and outputs an average value detection signal.
And a second differential amplifier that differentially amplifies a voltage corresponding to a difference between the voltage value of the average value detection signal and the voltage value of the negative phase signal peak output signal and outputs an applied voltage signal. Optical receiving circuit. 4. The burst light receiving circuit according to claim 3, wherein the emitter side is grounded via a resistor, and
A burst light receiving circuit comprising: a transistor that controls an input current of the preamplifier by a collector based on a potential of the applied voltage signal applied to a base. 5. The light receiving element according to claim 1, wherein the light receiving element receives the burst light signal, converts the received signal into an electric signal, and outputs the input burst signal. An identification circuit for identifying a differential value of the burst output signal and outputting a received output signal. 6. A station comprising the burst optical receiving circuit according to claim 5, and a plurality of subscriber stations for transmitting the burst optical signal while varying the burst optical signal so as to have different amplitudes. PDS system.