JP4921510B2 - Burst optical receiver - Google Patents

Description

  The present invention relates to a burst optical receiver that receives burst optical signals.

  FIG. 1 is a block diagram illustrating a conventional burst optical receiver. A conventional burst light receiving apparatus receives a burst light signal and outputs a current signal I1, a light receiving element 11 that converts the current signal I1 into a voltage signal V6, and a monitor signal I2 that duplicates the current signal I1. And a control circuit 14 that adjusts the conversion gain of the conversion circuit 13 based on the monitor signal I2 using the control signal V5 (see, for example, Patent Document 1). The control circuit 14 includes an integration circuit 22 and an amplification circuit 24. The integration circuit 22 outputs an integration signal V4 obtained by integrating the monitor signal I2. The amplifier circuit 24 generates a control signal V5 from the integration signal V4. The control circuit 14 has a reset terminal 15 and performs a reset operation for resetting the control signal V5 every time the burst period of the burst optical signal L ends.

  The optical intensity of the burst optical signal L received by the burst optical receiver varies depending on the distance from each burst optical transmitter. In the conventional burst light receiving apparatus, the control circuit 14 adjusts the conversion gain of the conversion circuit 13 based on the magnitude of the monitor signal I2, that is, the light intensity of the burst light signal L. A conventional burst light receiving apparatus can suppress waveform distortion even when a burst light signal L having a high light intensity is received.

Japanese Patent No. 3329302

  FIG. 2 is a timing chart for explaining signal waveforms output from the respective components when the conventional burst optical receiver receives the burst optical signal L. FIG. (L) is a waveform of the burst optical signal L, (1) is a waveform of the current signal I1 output from the light receiving element 11, (2) is a waveform of the monitor signal I2 output from the current mirror circuit 12, and (4) is an integration circuit. 22 shows the waveform of the integration signal V4 output, and (5) shows the waveform of the control signal V5 output by the control circuit 14. When the light receiving element 11 receives the burst light signal L, it outputs a current signal I1 (FIG. 2 (1)). The current mirror circuit 12 outputs a monitor signal I2 obtained by duplicating the current signal I1 ((2) in FIG. 2). Since the response speed of the current mirror circuit 12 is slow, the monitor signal I2 is delayed with respect to the current signal I1 as shown in FIG.

  Since the integration signal 22 is input to the integration circuit 22, the integration signal V4 is also delayed (FIG. 2 (4)), and since the integration signal V4 is input to the amplification circuit 24, the control signal V5 is also delayed (FIG. 2). 2 (5)). When the burst optical signal L is low speed, the influence of the delay of the control signal V5 is small, but when the burst optical signal is high speed, the influence of the delay of the control signal V5 becomes large.

  FIG. 3 is a diagram for explaining an output response of a conventional burst light receiving apparatus when a burst optical signal having a light intensity of −26 dBm is received immediately after a burst optical signal having a light intensity of −6 dBm with a burst period of 100 μsec. (A) is a figure explaining the output response at the time of the head of a burst optical signal with light intensity -6dBm, (b) is a figure explaining the output response at the time of the burst optical signal of light intensity -26dBm. It takes 1000 nsec for a burst optical signal with a light intensity of −6 dBm and 1400 nsec for a burst optical signal with a light intensity of −26 dBm until the output is stabilized.

  Thus, the conventional burst optical receiver has a problem that it is difficult to apply to an optical transmission system that uses a high-speed burst optical signal such as 10G-EPON (IEEE 802.3av). SUMMARY OF THE INVENTION An object of the present invention is to provide a burst optical receiver that can improve the response of the conversion gain adjustment of the conversion circuit and receive a high-speed burst optical signal.

  In order to achieve the above object, the burst light receiving apparatus according to the present invention uses a differential signal obtained by differentiating the current signal from the light receiving element.

  Specifically, the burst light receiving apparatus according to the present invention includes a light receiving element that receives a burst light signal and outputs a current signal, a conversion circuit that converts the current signal of the light receiving element into a voltage signal, and the light receiving element. Current mirror circuit that outputs a monitor signal that is a duplicate of the current signal, a differential circuit that outputs a differential signal obtained by differentiating the current signal of the light receiving element, a monitor signal that is output from the current mirror circuit, and the differential circuit that is output And a control circuit for adjusting the conversion gain of the conversion circuit based on the differential signal.

  The burst light receiving apparatus adjusts the conversion gain of the conversion circuit using the monitor signal and the differential signal. When the intensity of the burst optical signal changes, that is, at the beginning of the burst section, the differential signal becomes large and a monitor signal with a slow response can be compensated. Therefore, the present invention can provide a burst optical receiver that can improve the response of the conversion gain adjustment of the conversion circuit and receive a high-speed burst optical signal.

  The control circuit of the burst light receiving device according to the present invention includes an integration circuit that integrates a monitor signal from the current mirror circuit, an addition circuit that adds an output of the integration circuit and a differential signal from the differentiation circuit, It is preferable to have. Since the differential signal is added after the integration circuit, the response can be improved.

  The present invention can provide a burst optical receiver capable of improving the response of the conversion gain adjustment of the conversion circuit and receiving a high-speed burst optical signal.

It is a block diagram explaining the conventional burst optical receiver. It is a timing chart explaining operation | movement of the conventional burst optical receiver. It is a figure explaining the output response of the conventional burst optical receiver. It is a block diagram explaining the burst optical receiver which concerns on this invention. 6 is a timing chart for explaining the operation of the burst optical receiver according to the present invention. It is a figure explaining the output response of the burst optical receiver which concerns on this invention.

  Hereinafter, the present invention will be described in detail with specific embodiments, but the present invention is not construed as being limited to the following description. In the present specification and drawings, the same reference numerals denote the same components.

  FIG. 4 is a block diagram for explaining the burst optical receiver of this embodiment. The burst light receiving device receives a burst light signal L and outputs a current signal I1, a conversion circuit 13 that converts a current signal I1 of the light receiving element 11 into a voltage signal V6, and a current of the light receiving element 11. A current mirror circuit 12 that outputs a monitor signal I2 that is a duplicate of the signal I1, a differential circuit 21 that outputs a differential signal V3 obtained by differentiating the current signal I1 of the light receiving element 11, a monitor signal I2 and a differential that the current mirror circuit 12 outputs And a control circuit 14 that adjusts the conversion gain of the conversion circuit 13 based on the differential signal V3 output from the circuit 21.

  The light receiving element 11 is, for example, a photodiode (PD). The current mirror circuit 12 outputs a monitor signal I2 obtained by copying the current signal I1. The conversion circuit 13 is a circuit that converts current into voltage, and is, for example, a transimpedance amplifier (TIA). The differentiation circuit 21 outputs a differential signal V3 obtained by differentiating the current signal I1.

  The control circuit 14 includes an integration circuit 22, an addition circuit 23, and an amplification circuit 24. The integration circuit 22 outputs an integration signal V4 obtained by integrating the monitor signal I2. The adding circuit 23 adds the differential signal V3 from the differentiating circuit 21 and the integrated signal V4 from the integrating circuit 22. The amplifier circuit 24 generates a control signal V5 from the output of the adder circuit 23.

  As described with reference to FIGS. 1 and 2, the control circuit 14 can suppress the waveform distortion of the voltage signal V6 by adjusting the conversion gain of the conversion circuit 13 with the component of the integration signal V4 in the output of the addition circuit 23. . Next, it will be described with reference to FIG. 5 that the delay of the control signal V5 can be reduced by adding the differential signal V3 to the integral signal V4.

  FIG. 5 is a timing chart for explaining signal waveforms output from the respective components when the burst optical receiver of the present embodiment receives a burst optical signal. (L) is the waveform of the burst optical signal L, (1) is the waveform of the current signal I1 output from the light receiving element 11, (2) is the waveform of the monitor signal I2 output from the current mirror circuit 12, and (3) is the differentiation circuit. 21 is a waveform of the differential signal V3 output from the control circuit 21, (4) is a waveform of the integration signal V4 output from the integration circuit 22, and (5) is a waveform of the control signal V5 output from the control circuit 14. When the light receiving element 11 receives the burst light signal L, the current signal I1 (FIG. 5 (1)) and the monitor signal I2 (FIG. 5 (2)) as described in FIG. 2 are generated. The differentiating circuit 21 differentiates the current signal I1 and outputs a differentiated signal V3 (FIG. 5 (3)). The integration circuit 22 integrates the monitor current I2 and outputs an integration signal V4 (FIG. 5 (4)).

  As described with reference to FIG. 2, the integration signal V4 is delayed compared to the current signal I1. Therefore, by adding the differential signal V3 to the integration signal V4 by the addition circuit 23, the delay of the integration signal V4 can be compensated. For this reason, the burst optical receiver of this embodiment can shorten the delay of the control signal V5 compared to the burst optical receiver of FIG. In order to adjust the conversion gain of the conversion circuit 13 using the control signal V5 as shown in FIG. 5 (5), the burst optical receiver of this embodiment follows the intensity change of the burst optical signal L and converts the conversion circuit 13. The conversion gain can be adjusted.

  FIG. 6 shows the output response of the burst light receiving apparatus of this embodiment when a burst optical signal having a light intensity of −26 dBm is received immediately after a burst optical signal having a light intensity of −6 dBm and the burst interval is 100 μsec, as in FIG. It is a figure explaining. (A) is a figure explaining the output response at the time of the head of a burst optical signal with light intensity -6dBm, (b) is a figure explaining the output response at the time of the burst optical signal of light intensity -26dBm. Until the output is stabilized, both the burst light signal with the light intensity of −6 dBm and the burst light signal with the light intensity of −26 dBm are 600 nsec, which is shorter than the stabilization time of the conventional burst light receiver.

  In addition, since the burst optical receiver of this embodiment has improved the responsiveness of the control signal V5 to the burst optical signal L, no reset operation is required. For this reason, the burst optical receiver according to the present embodiment can eliminate the need for a circuit that generates a reset signal that has been input to the control circuit 14 in the past.

11: light receiving element 12: current mirror circuit 13: conversion circuit 14: control circuit 15: reset terminal 17: output terminal 21: differentiation circuit 22: integration circuit 23: addition circuit 24: amplification circuit L: burst optical signal I1: current signal I2: Monitor signal V3: Differential signal V4: Integration signal V5: Control signal V6: Voltage signal

Claims (2)

A light receiving element that receives a burst optical signal and outputs a current signal;
A conversion circuit that converts a current signal of the light receiving element into a voltage signal;
A current mirror circuit that outputs a monitor signal obtained by duplicating the current signal of the light receiving element;
A differentiating circuit for outputting a differential signal obtained by differentiating the current signal of the light receiving element;
A control circuit for adjusting the conversion gain of the conversion circuit based on the monitor signal output by the current mirror circuit and the differential signal output by the differentiation circuit;
A burst optical receiver. The control circuit includes:
An integrating circuit for integrating the monitor signal from the current mirror circuit;
An adding circuit for adding the output of the integrating circuit and the differential signal from the differentiating circuit;
The burst optical receiver according to claim 1, wherein

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