WO1998013958A1 - Module et systeme pour la transmission optique - Google Patents

Module et systeme pour la transmission optique Download PDF

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Publication number
WO1998013958A1
WO1998013958A1 PCT/JP1996/002817 JP9602817W WO9813958A1 WO 1998013958 A1 WO1998013958 A1 WO 1998013958A1 JP 9602817 W JP9602817 W JP 9602817W WO 9813958 A1 WO9813958 A1 WO 9813958A1
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WO
WIPO (PCT)
Prior art keywords
optical
signal
output
input
optical transmission
Prior art date
Application number
PCT/JP1996/002817
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English (en)
Japanese (ja)
Inventor
Hiroaki Hanawa
Makoto Haneda
Original Assignee
Hitachi, Ltd.
Hitachi Microcomputer System, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi, Ltd., Hitachi Microcomputer System, Ltd. filed Critical Hitachi, Ltd.
Priority to PCT/JP1996/002817 priority Critical patent/WO1998013958A1/fr
Publication of WO1998013958A1 publication Critical patent/WO1998013958A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers

Definitions

  • the present invention relates to an optical transmission module and an optical transmission system, and relates to a technology that is effective when applied to introduce an optical cable such as an optical fiber into a subscriber system such as a telephone or an integrated service digital network (ISDN).
  • ISDN integrated service digital network
  • optical transmission module is a module that bidirectionally converts an optical signal and an electric signal.
  • the optical transmitting side includes, for example, a laser diode and its driving circuit
  • the optical receiving side includes a photo diode and a signal extracting circuit. Is provided. Examples of documents describing the optical transmission system include “LSI Handbook”, pp. 1004 and 1005, published by OAM Co., Ltd. (December 25, 1960).
  • SONET—SDH Synchronous Optical
  • a synchronous continuous transmission system typified by a Network-Synchronous Digital Hierarchy
  • a burst transmission system typified by a PDS (Passive Double Star) system.
  • the present invention has been made in view of the above circumstances, and provides an optical transmission module and an optical transmission system capable of changing a transmission method with an electric communication system.
  • Another object of the present invention is to provide an optical transmission module that can easily change the circuit characteristics or the mode of circuit operation.
  • Another object of the present invention is to provide an optical transmission system in which a host device can intensively change a circuit characteristic or a circuit operation mode of an optical transmission module of a terminal device.
  • An optical transmission module includes an optical transmitting unit that converts an input electric signal into an optical signal and outputs the same, and an optical receiving unit that converts the input optical signal into an electric signal and outputs the same.
  • the optical transmission module may include a case where the electric signal is compatible with a synchronous transfer accompanied by a synchronous clock signal for synchronizing the electric signal with the data signal, and a case where the electric signal transmits the synchronous clock signal to the data signal.
  • Control means is provided for controlling the switching of the operations of the optical transmission unit and the optical reception unit to the synchronous transfer mode or the burst transfer mode according to the case where burst transfer without accompanying is supported.
  • the synchronous transfer mode corresponds to a synchronous continuous transmission system represented by, for example, a SONET-SDH system
  • the burst transfer mode corresponds to a burst transmission system represented by, for example, a PDS system. Things.
  • the control means includes an input / output circuit for externally inputting first control information for instructing which of the synchronous transfer mode and the burst transfer mode is to be employed, and a rewritable first control information.
  • a CPU for controlling the optical transmitting unit and the optical receiving unit in the synchronous transfer mode or the burst transfer mode based on the first control information stored in the nonvolatile storage unit. Can be configured. By a simple operation of rewriting the first control information, the transmission method with the electric signal system can be easily changed.
  • the control means may be a one-chip microcomputer in which the CPu, the input / output circuit, and the nonvolatile storage means share an internal path.
  • the microcomputer further includes host interface means coupled to the microcomputer via the input / output circuit, and the host interface means inputs the electric signal converted by the optical receiver, and By signal Based on the decoding result of the given command, the first control information and the second control information for storing the first control information in the non-volatile storage unit are stored in the micro-combination table. You can give it. With this, it becomes possible to instruct via the optical cable whether the optical transmission module selects the synchronous transfer mode or the burst transfer mode.
  • the micro-computer inputs the electric signal converted by the optical receiving unit from the input / output circuit, and based on the decoding result of a predetermined command given by the input signal, the CPU The first control information is stored in the nonvolatile memory.
  • An optical transmission system using such an optical transmission module includes a communication host device and a plurality of communication terminal devices connected to the communication host device by an optical cable, and the communication host device and the communication terminal device Includes the optical transmission modules respectively connected to the optical cables. At this time, the host device outputs the predetermined command to the optical cable. Thereby, the communication host device can intensively change the operation mode of the optical transmission module of the communication terminal device.
  • the above viewpoint focuses on the data transfer mode with the electric signal system among the circuit characteristics of the optical transmission module, and makes it possible to switch the mode.
  • the present invention has another viewpoint in which the circuit characteristics of the optical transmission module are grasped in a broad sense, and the circuit characteristics and the mode of the circuit operation can be changed.
  • the optical transmission module converts an input electric signal into an optical signal and outputs the same, an optical receiver that converts the input optical signal into an electric signal and outputs the same, A microphone port computer for controlling the operation of the light receiving unit.
  • the micro-computer overnight, each internal bus A host interface including a shared CPU, an input / output circuit, and electrically rewritable nonvolatile storage means, coupled to the micro computer via the input / output circuit;
  • the evening face means inputs the electric signal converted by the light receiving unit, and based on a result of decoding a predetermined command given by the input signal, the light transmitting unit or the light receiving unit by the CPU.
  • first control information for changing at least one control mode and second control information for storing the first control information in the non-volatile storage means to the micro computer. It is. As a result, it becomes possible to instruct via the optical cable to change the circuit characteristics or the operation mode of the circuit in the optical transmission module. Further, it is also possible to realize the function of the host interface unit in the microcomputer. That is, the microcomputer inputs the electric signal converted by the optical receiving unit from the input / output circuit, and the CPU performs the processing based on a result of decoding a predetermined command given by the input signal. First control information for changing a control mode of at least one of an optical transmitting unit and an optical receiving unit is stored in the nonvolatile storage unit.
  • An optical transmission system using such an optical transmission module includes a communication host device and a plurality of communication terminal devices connected to the communication host device by an optical cable, and the communication host device and the communication terminal device Includes the optical transmission modules respectively connected to the optical cables. At this time, the host device outputs the predetermined command and the first control information to the optical cable.
  • the communication host device can intensively change the circuit characteristics or the circuit operation mode of the optical transmission module of the communication terminal device.
  • the circuit characteristics to be changed include the drive characteristics for the laser diode.
  • the first control information includes a laser diode by the driver circuit.
  • the characteristic information is used to change the drive current to the nonvolatile memory according to the temperature and the target light output.
  • the command is an operation of writing new characteristic information to the non-volatile storage means by a micro computer. It shall be instructed in the evening.
  • the circuit characteristics can be efficiently controlled from the communication host device side. Can be changed.
  • Another circuit characteristic to be changed is the gain of the amplifier. That is, when the optical receiver includes a photodiode that receives an optical signal from an optical cable, and an amplifier that amplifies the output of the photodiode, the first control information changes the gain of the amplifier. At this time, the command instructs the microcomputer to perform an operation for writing new first control information in the nonvolatile storage means. According to this, when the line load increases or decreases due to an increase in the scale of the system or the like, the reception sensitivity of the optical transmission module affected by the load can be changed intensively from the communication host device side.
  • the first control information includes a case where the electric signal corresponds to a synchronous transfer accompanied by a synchronous clock signal for synchronizing the electric signal with the data signal, and a case where the electric signal does not accompany the synchronous clock signal to the data signal.
  • the control information is control information for controlling the switching of the operation of the optical transmission unit and the optical reception unit to the synchronous transfer mode or the burst transfer mode.
  • the command is the non-volatile storage
  • the operation for writing the new first control information into the means shall be instructed by the microcombiner.
  • the CPU can control the operation of the optical transmitting unit and the optical receiving unit to be switched to a synchronous transfer mode or a burst transfer mode based on the first control information written in the nonvolatile storage unit.
  • FIG. 1 is a block diagram of an optical transmission module according to one embodiment of the present invention
  • FIG. 2 is a block diagram of an optical transmission module according to another embodiment of the present invention
  • FIG. 4 is an explanatory diagram showing that the forward current Id required to obtain a certain light output is nonlinearly changed with temperature.
  • FIG. 5 is a circuit diagram showing a detailed example of the optical transmitter.
  • FIG. 6 is a circuit diagram showing an example of a switching control circuit of a transistor for controlling on / off of a current path of a laser diode.
  • FIG. 7 is a main flowchart of the LD drive control by the CPU
  • FIG. 8 is a flowchart showing a process when the burst transfer mode is set.
  • FIG. 9 is a flowchart showing a process when a shirt down is instructed.
  • FIG. 10 is a block diagram showing an example of a PDS system as an optical transmission system. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a block diagram of an optical transmission module according to one embodiment of the present invention.
  • the optical transmission module 1 shown in FIG. 1 includes an LD module 10, a driver circuit 11, and an input circuit 12, each of which constitutes an optical transmission unit (optical transmitter) and individually formed as a semiconductor integrated circuit. It comprises a bin photodiode 13, a preamplifier 14, a main amplifier 15, and an output circuit 16, each of which constitutes an optical receiver (optical receiver) and individually formed as a semiconductor integrated circuit.
  • the LD module 100 has a laser diode (also referred to as LD) 100 and a photodiode for monitoring (also referred to as PD) 101.
  • the optical output of the laser diode 100 is an optical output terminal 0P. Output to OUT.
  • the bin photodiode 13 receives an optical signal from an optical input terminal OPIN.
  • the input circuit 12 is connected to the data input terminal D TIN and the clock input terminal C LIN, and the output circuit 16 is connected to the data output terminal D TOUT and the clock output terminal CLOUT.
  • the input circuit 12 has an input buffer 120 composed of a D-type flip-flop and a selector 121.
  • the input buffer 12 sequentially latches the data signal from the DTIN in synchronization with the clock signal from the terminal CLIN, thereby using the clock signal supplied from the clock input terminal CLIN to the data input terminal. Shapes the overnight signal supplied from DTIN.
  • the selector 122 selects the data signal whose waveform has been shaped by the input buffer 120 or the data signal whose waveform has not been shaped, and transmits it to the subsequent stage.
  • the driver circuit 111 has an LD driver 110 and an auto power control circuit (APC) 111, and the LD driver is -110.
  • the data signal supplied via the selector 121 is a data signal. Is converted into a drive signal current necessary for the LD 100 to obtain the optical output of the target specification, and the LD 100 threshold is Generates a DC bias current to guarantee the value current and supplies it to the LD 100.
  • the DC bias current is automatically controlled based on the detection result of the current (LD light output monitor current) detected by the PD 101 so that the light output is always constant at the APC 111.
  • the optical output of the LD 100 is provided from the optical output terminal 0 POUT to a transmission line such as an optical fiber.
  • the bin photodiode 13 detects the optical signal supplied from the transmission line to the optical input terminal 0 P I and converts it into a received signal current. This signal current is converted by the preamplifier 14 into a voltage signal. The converted voltage signal is provided to the main amplifier 15. The main amplifier 15 amplifies the input voltage signal to the ECL level.
  • the output circuit 16 that receives the output of the main amplifier 15 includes a timing extraction unit 160, an identification unit 161, an output buffer 162 such as a flip-flop, and a selector 163.
  • the timing extraction unit 160 branches the input signal into two systems, delays one of them, and ANDs it with the other to generate a pulse including a clock component of, for example, 155.52 MHz.
  • the identification unit 161 sufficiently amplifies the input signal from the main amplifier 15 and shapes the upper and lower parts of the waveform into a sliced signal.
  • the output buffer 162 performs waveform shaping (suppression of pulse width distortion) on the sliced signal by using the peak signal.
  • the selector 163 selects the output of the discrimination section 16 1 or the output of the output buffer 162, and outputs a data signal from the data output terminal DTOUT.
  • the clock signal generated by the timing extractor 160 is supplied to a clock output terminal CLOUT.
  • the optical transmission module 1 shown in FIG. 1 includes a microcombiner 17.
  • This micro combination 17 is not particularly limited, but C PU (Central Processing Unit) 17 0, RAM (Random Access Memory) 17 1, ROM (Read Only Memory) 1 72, Flash memory 1 ⁇ ⁇ 3 which is an example of nonvolatile memory device that can be electrically erased and written , And an input / output circuit (I / O) 174, etc., which are coupled to the internal bus 175.
  • C PU Central Processing Unit
  • RAM Random Access Memory
  • ROM Read Only Memory
  • Flash memory 1 ⁇ ⁇ 3 which is an example of nonvolatile memory device that can be electrically erased and written
  • I / O input / output circuit
  • the ROM 172 is a mask ROM having an operation program of the CPU 170 and a constant data memory
  • the RAM 171 is a work area of the CPU 170 and a flash memory 173 Holds the operation program and control data of the CPU 170 in a rewritable manner.
  • the microcomputer 17 is a circuit that controls the entire optical transmission module 1. The details of the control contents will be described later, but typically have the following control contents. The first is control of switching the data transfer mode between the DT IN and DT OUT side electrical signal systems. The second is switching control of the gain of the preamplifier 14. Third is the drive current control of the LD 100 by the LD driver 110.
  • the third control content uses a data table created based on the temperature characteristics of the LD 100, and controls the LD 100 according to the light output and temperature required by the LD 100.
  • the microcomputer 17 is a data processing device that controls the semiconductor device according to the characteristic information of the semiconductor device measured in advance. Will be realized.
  • the data output terminal D OUT is connected to an input terminal of a system decoder 18 as a host-side interface means.
  • the output terminal of the system decoder 18 is connected to the input / output circuit 174.
  • the system decoder 18 decodes a command contained in the data signal supplied via the optical input terminal OPIN, and supplies control information to the human output circuits 1-4 according to the decoding result.
  • the rewriting of the flash memory 173 is performed based on the control information.
  • the system decoder 1 8 sets the specific operation mode described above in the micro-computer 17 when rewriting the flash memory 173, and then sets a strobe signal or flash memory command to directly control the flash memory 173. And outputs the write data and write address.
  • the write data and the write address may be automatically generated by the system decoder 18 in accordance with a command given to the system decoder 18, or the data supplied via the optical input terminal OPIN may be used. Alternatively, it may be provided to the flash memory 173.
  • the system decoder 18 can control the microcontroller by an interrupt or the like. Pew evening 17 can be instructed to rewrite flash memory 1-3.
  • the system decoder 18 can give the write data and write address at that time to the microcomputer 17. Alternatively, the write address can be fixedly designated by the rewrite control program.
  • the write data is given from the system decoder 18.
  • the system decoder 18 is unnecessary as shown in FIG. In that case, however, the microcomputer 17 will use the CPU 17 as the flash memory according to the rewrite control program stored in the ROM 172. 173 must be able to control rewriting.
  • the input / output circuit 174 is also connected to the input terminal of the LD driver 110, whereby the microcomputer 17 can send required information from the optical output terminal OPOUT.
  • the optical transmission module 1 can rewrite the flash memory 173 in accordance with the command supplied via the optical input terminal 0 PIN, and the CPU 170 uses the rewritten control information to generate the data signal terminal DT Switching of data transfer mode between IN and DTOUT side electrical signal system, switching of gain of preamplifier 14, download of new data table for controlling LD 100 drive current by LD driver 110 Etc. are enabled.
  • the electric signals exchanged with the optical transmission module are a data signal and a cou- pling signal.
  • the data transfer rate at this time ranges, for example, from several mega to several gigabits per second.
  • the synchronization signal synchronous clock signal
  • the only electrical signals exchanged with the optical transmission module are data signals.
  • the data transfer rate at this time is, for example, several tens to several hundreds of megabits per second.
  • the synchronization method in the case where the synchronization signal is not provided separately from the overnight signal is not particularly related to the function of the optical transmission module itself, but is a known start-stop synchronization or frame synchronization.
  • frame synchronization is used.
  • burst transfer Such a case where a synchronization signal (synchronous clock signal) is not provided separately from the overnight signal is called burst transfer.
  • the micro-computer 17 controls the operation of the optical transmission unit and the optical reception unit in a synchronous transfer mode according to whether the optical transmission module 1 is compatible with synchronous transfer and whether the optical transmission module 1 is compatible with burst transfer. Or, switch to burst transfer mode and control.
  • the output of 0 is selected, and the output of the output buffer 162 is selected as the output of the selector 163.
  • the waveform is shaped by being sequentially latched in the input buffer 120 in synchronization with the synchronous clock signal.
  • the output data signal is output together with the synchronous clock signal with its pulse width distortion suppressed by the synchronous clock signal.
  • the data signal supplied from the data input terminal DTIN is directly selected as the output of the selector 121, and the data output from the discriminator as the output of the selector 163.
  • the signal is selected as is.
  • the clock terminals CLIN and CLOUT are practically not used.
  • Whether to use the synchronous transfer mode or the burst transfer mode is determined by the specifications of the circuit coupled to the electric signal system of the optical transmission module 1 or the system using the optical transmission module.
  • the selection control of the selectors 12 1 and 16 3 is performed by the control signals S 1 and S 2 output from the input / output circuit 17 4 of the micro-computer 1.
  • the control data (transfer mode control data) for that purpose is stored in a predetermined control data area of the flash memory 173, for example.
  • the default value of the transfer mode control is not particularly limited, but is set to a value for selecting the synchronous transfer mode.
  • the setting of the default value is not particularly limited, but is performed in the manufacturing process of the optical transmission module.
  • the microcomputer 17 performs one of the initialization operations as follows. Transfer of the control data storage area of the flash memory 173 The mode control data is read out, transferred to a predetermined port of the input / output circuit 174, and the selectors 121, Supply control signals S 1 and S 2 to 16 3.
  • the system decoder 18 decodes the command.
  • the system decoder 18 gives an operation mode setting signal to the microcomputer 17 to make the flash memory 1773 seem to be a flash memory M, and then to the flash 17 It provides an address signal, strobe signal and write data for rewriting the transfer mode control data of the memory.
  • the command includes, in addition to predetermined code information for instructing rewriting of the transfer mode control data, for example, whether to set the transfer mode to the synchronous transfer mode or the burst transfer mode. Is added.
  • a write data is generated according to the additional information.
  • the write address can be generated by the system decoder 18 according to the predetermined code information. The write address may be supplied later through the optical input terminal 0 PIN.
  • the command decoder 18 Is the first command to switch the synchronous transfer mode to the burst transfer mode, or the burst transfer mode is switched to the synchronous transfer mode.
  • an interrupt request corresponding to the result of the decoding is given to the MAC port combination 17.
  • the microcomputer 17 branches the CPU 170 to a process corresponding to the interrupt request, whereby the transfer mode control data is rewritten according to the ROM rewrite control program.
  • Whether the transfer mode control data is rewritten to the burst transfer mode or the synchronous transfer mode is determined by assigning the interrupt request itself to each transfer mode, or after the interrupt request. At the same time, control information for instructing the transfer mode to be rewritten may be given as a parameter.
  • the transfer control data is rewritten by the CPU 170 in accordance with the rewrite control program of the ROM 172.
  • the operation is instructed by a method in which the CPU 170 decodes the interrupt request described above or the command supplied from the optical input terminal OPIN, and branches the internal processing to rewrite the transfer control data. Can be.
  • the length of an optical fiber connecting a center device including the optical transmission module and a number of network terminating devices is not necessarily constant.
  • the signal reception sensitivity of the optical transmission module is expected to decrease later. To cope with this, the gain of the preamplifier 14 is switchable.
  • the circuit configuration of the preamplifier is not shown in FIG. 1 and FIG. 2, for example, an inverting or non-inverting amplifying circuit using a known operational amplifier can be used. In that case, the gain of the amplifier is inverted from the output of the operational amplifier. It can be determined by the ratio of the feedback impedance to the input terminal and the input impedance to the non-inverting input terminal.
  • the preamplifier 14 is configured to be able to switch the feedback impedance or the input impedance to a plurality of stages by a switch arranged in a ladder resistance network. That is, the gain of the preamplifier 14 can be switched in a plurality of stages.
  • the microcomputer 17 outputs to the preamplifier 14 a plurality of bits of a control signal S3 for switching and controlling the gain of the preamplifier 14.
  • the control signal S 3 is output from the input / output circuits 1-4 of the microcomputer 17.
  • the control data (gain control data) for generating the control signal S3 is stored in a predetermined control data area of the flash memory 173, for example.
  • the default value of the gain control data is not particularly limited, but is determined when the center device including the optical transmission module or the network termination device is hidden.
  • the setting of the default value is not particularly limited, but is performed in the manufacturing process of the optical transmission module or in the installation work.
  • the microcomputer 17 starts the initialization operation.
  • the gain control data in the predetermined control data storage area of the flash memories 1 to 3 is read out, transferred to a predetermined port of the input / output circuit 1.4, and is read from the port.
  • the system decoder 18 decodes the command.
  • the system decoder 18 can be used to make the microcomputer 17 look and be identical to the flash memory 173.
  • the operation mode setting signal is given to the microcomputer 17 and then an address signal, a strobe signal and a write data for rewriting the gain control data of the flash memory are given.
  • an address signal, a strobe signal and a write data for rewriting the gain control data of the flash memory are given.
  • the predetermined code information for instructing rewriting of the gain control data for example, information indicating a gain setting level is added to the command.
  • Write data is generated according to this additional information.
  • the write address can be generated by the system decoder 18 according to the predetermined code information. The write address may be supplied later via the optical input terminal PIN.
  • the command decoder 18 decodes the gain change command and the decoding result
  • An interrupt request corresponding to the above is given to the macro combination 17.
  • the microcomputer 17 branches the CPU 170 into a process corresponding to the interrupt request, whereby the gain control data is rewritten according to the ROM rewrite control program.
  • the value of the gain control data can be determined by assigning the interrupt request itself according to the gain setting level, or specifying the gain control data to be rewritten after or simultaneously with the interrupt request. Control information to be given may be given as parameters. In the case of the configuration shown in FIG.
  • the rewriting of the gain control data is performed by the CPU 170 in accordance with the rewriting control program of the ROM 172.
  • the operation is instructed by the CPU 170 decoding the interrupt request or the command supplied from the optical input terminal OPIN, and branching the internal processing to rewriting the gain control data. be able to.
  • the LD 100 has a double heterojunction, and when a forward current flows through it, when the current exceeds a certain current value, the laser starts laser oscillation and emits laser light. This current at the start of laser oscillation is called a threshold current I th.
  • the magnitude of the forward current Id to be passed through the laser diode is determined according to the required light output. This forward current Id can be roughly expressed as Ith + Imod.
  • I mod is referred to as modulation current, and the optical output of LD 10 is obtained by passing the modulation current out of the required forward current to the LD or by cutting off the modulation current (called modulation current on / off control). Can be turned on / off.
  • the LD 100 has a temperature dependency on a light output with respect to a forward current. Therefore, in order to correct the base voltage of the current source transistor arranged in the drive current path of LD 100 according to the temperature, the temperature dependence of the band gap of the transistor or diode is added to the bias circuit of the current source transistor. Can be adopted.
  • the temperature characteristics of LD100 differ greatly depending on the temperature as illustrated in FIG.
  • the characteristics of the threshold current and the modulation current differ depending on the temperature. That is, the forward current of the LD 100 required for obtaining a predetermined light output differs depending on the temperature, and at this time, the threshold current included in the forward current also differs independently according to the temperature. You. Therefore, the modulation current, which is the difference between the forward current and the threshold current, also changes in accordance with the temperature. In FIG.
  • the threshold currents I th (i), I th (j), I th (k) and the modulation currents I mod (i), I mod (j), and I mod (k) are the values of the exemplified temperatures T (i), ⁇ (j), and ⁇ (k). They are greatly different in each. Therefore, the forward current I d required to obtain a certain light output is changed non-linearly with respect to temperature, as illustrated in FIG. Similarly, the threshold current and the modulation current are also nonlinearly changed.
  • the current characteristic of the base bias circuit with respect to temperature utilizing the temperature dependence of the band gap of a transistor or a diode is only changed linearly. Due to this difference, a base bias circuit that utilizes the temperature dependence of the band gap of a transistor or a diode cannot accurately compensate for the LD drive current with respect to temperature changes.
  • the actual light emission output of the LD 100 is monitored by a photo diode (PD) 101, and the current corresponding to the monitored light emission output is monitored. It is possible to determine by comparison whether the voltage is lower or higher than the reference potential V ref corresponding to the required light emission output, and if it is lower, control can be performed to increase the bias current flowing to the LD.
  • PD photo diode
  • the current controlled on / off by the transistor that flows current to the LD 100 to control the optical output of the LD 100 on / off does not conform to the temperature characteristics of the LD at that time.
  • the forward current required to obtain the required light emission output for the LD at the temperature T (j) is I d (j), and the drive that can be supplied by the LD drive circuit at this time
  • the difference current is Power control adds to the bias current of the LD.
  • This difference current is not subject to on / off control as a modulation current.
  • the current value when the modulation current is turned off is larger than the threshold current, causing extinction failure, or the current value when the modulation current is turned off is smaller than the threshold current. Inconveniences such as light emission delay due to reduction in size occur.
  • the modulation current that can flow in the current source transistor is I1 (I1 ⁇ Imod (k)) due to the temperature characteristics of this transistor and the like. If so, a bias current I 2 (I 2> I th (k)) flows in the bias range in order to obtain the light emission output P m. Then, when the modulation current I 1 is made zero to turn off the LD, the bias current flowing through the LD exceeds the threshold current I th (k) of the LD at the temperature T (k) at that time. This does not completely extinguish the LD.
  • I1 I1 ⁇ Imod (k)
  • the modulated current that can flow through the current source transistor in the atmosphere of the temperature T (i) is I 3 (I 3> I th (i)) due to the temperature characteristics of the transistor and the like. Then, in order to obtain the optical output Pm, a bias current 14 (I4 ⁇ Ith (i)) flows in the bias transistor.
  • the modulation current I 3 is made zero to turn off the LD
  • the bias current flowing through the LD becomes the threshold current I th (i) of the LD at the temperature T (i) at that time. Therefore, the next time the LD is turned on, the LD must first wait for a delay time until the modulation current flowing through the LD exceeds its threshold voltage I th (i). Is emitted.
  • the optical transmission module 1 of the present embodiment drives the LD 100 in consideration of the difference between the temperature characteristics of the laser diode 100 and the temperature characteristics of the LD driver 110 in order to prevent such a light emission delay and extinction failure. Can control the current I am trying to. First, the contents will be described.
  • FIG. 5 shows a detailed example of the optical transmission.
  • the LD dryno 110 is connected to a transistor T r2 which determines a bias current flowing through the LD 100 and a transistor Tr r 2 which determines a modulation current for controlling on / off of the LD 100.
  • the transistors Tr 3 and Tr 4 are switching transistors for controlling on / off of the modulation current.
  • the transistors Tr 3 and Tr 4 are connected in parallel, the common emitter is connected to the collector of the transistor Tr 2, and the emitter of the transistor Tr 2 is connected to the negative terminal via a resistor R 2. ' ⁇ ! It is coupled to a source voltage V e e (eg, one-5.2 V). A cathode of the LD 100 is coupled to the collector of the transistor Tr 3, and the anode of the LD 100 and the collector of the transistor Tr 4 are connected to the other power supply voltage V such as a ground potential. Commonly connected to cc (for example, 0V).
  • a switching control circuit 114 for the transistors Tr 3 and Tr 4 includes a series circuit of transistors Tr 5 and Tr 6, a transistor Tr 7 and a transistor Tr 7.
  • the series circuit of r8 is arranged between the pair of power supply voltages Vcc and Vee.
  • the transistors Tr 5 to Tr 8 are npn-type bipolar transistors.
  • the bases of the transistors Tr6 and Tr8 are biased at a predetermined voltage and function as load resistors for the transistors Tr5 and Tr7.
  • the series circuit of the transistors Tr 5 and Tr 6 and the series circuit of the transistors Tr 7 and Tr 8 each constitute an emitter follower circuit, and the emitter of the transistor Tr 5 At the pace of the transistor Tr3, the emitter of the transistor Tr7 is coupled to the base of the transistor Tr4.
  • the bases of the transistors Tr5 and Tr7 are supplied with the differential output of the differential output amplifier AMP, and when the inputs are inverted, the states of the base potentials of the transistors Tr3 and Tr4 are inverted. It has become so.
  • the output of the selector 121 is supplied to the amplifier AMP.
  • the transistor Tr 3 When the base potential of the transistor Tr 3 is set to a high level, the transistor Tr 3 is shifted to a saturation state, and when the base of the transistor Tr 4 is set to a high level, the transistor Tr 4 is shifted to a saturation state. .
  • the transition of the transistors Tr3 and ⁇ r4 to the saturation state is performed complementarily, and the transistors Tr3 and Tr4 are switched in a complementary manner.
  • the modulation current is supplied to the LD 100 in a pulse form via the transistor Tr2.
  • the transistor Tr1 has its collector coupled to the collector of the transistor Tr3, and its emitter coupled to the power supply voltage Vee via a resistor R1.
  • This transistor Tr 1 supplies a bias current to the LD 100 according to the base voltage applied to it.
  • the PD 101 is connected in series with the resistor R3, and is arranged in a reverse connection state between the pair of power supply voltages Vcc and Vee.
  • the PD 101 supplies a current according to the light output output from the LD 100.
  • an input / output circuit 174 of the micro-computer 17 is a digital / analog conversion circuit (D / A) 176 for converting a digital signal into an analog signal, and a digital / digital converter for converting the analog signal to a digital signal.
  • the analog conversion circuit (A / D) 177 and the other input / output circuit 178 are shown separately.
  • the D / A 176 has two D / A conversion channels DAC1 and DAC2, and the A / D 177 has four A / D conversion channels ADC1 to ADC4.
  • Each of the D / A conversion channels DAC 1 and DAC 2 has a unique register accessed by the CPU 170, and performs D / A conversion on the value of the corresponding register to obtain transistors T rl and T Outputs r2 base spice voltage.
  • the D / A conversion channels DAC 1 and DAC 2 convert an 8-bit digital signal into an analog signal at 256 gradations.
  • the modulation current to be passed to the transistor Tr 3 in accordance with the ON / OFF control of the optical output is determined by the control data set by the CPU 170 in the D / A conversion channel DAC 2. That is, it is determined by the conductance control of the transistor Tr2.
  • the conductance control of the transistor Tr 2 is called modulation current control.
  • the bias current to be supplied to the LD 100 is determined by the control data set in the D / A conversion channel DAC 1 by the CPU 170. That is, it is determined by the conductance control of the transistor Trl.
  • the conductance control of the transistor Tr1 is referred to as the LD bias current control.
  • the CPU 170 individually and arbitrarily controls the modulation current and the bias current that can be supplied to the LD 100 in accordance with the digital data set in the D / A conversion channels D AC 1 and DAC 2. Can be. Therefore, the CPU 170 sets the D / A conversion channels D AC1 and D AC 2 to the data that conforms to the temperature characteristics of the LD 100, etc., for the operating conditions (operating atmosphere conditions) of the optical transmission module 1. In other words, the data corresponding to the threshold current of LD 100 at the operating temperature at that time is set to D / A conversion channel DAC 1 and the required optical output is set at that temperature.
  • the LD 100 can be driven to emit light without extinction error or emission delay. Becomes possible.
  • the A / D conversion channels ADC 1 to ADC 4 are sequentially connected to the transistor Tr 1 emitter voltage, the transistor Tr 2 emitter voltage, the PD 101 anode voltage, and the temperature.
  • Each of the registers has a unique register assigned to the input of the detection output voltage of the sensor 112 and holding the A / D conversion result for the assigned input voltage in an accessible manner by the CPU 170.
  • the A / D conversion channels ADC1 to ADC4 have a conversion accuracy of 10 bits.
  • the CPU 170 converts the bias current flowing through the transistor Tr1, the current flowing through the transistor Tr2, the current flowing through the PD 201, and the output of the temperature sensor 1 ° into an A / D converter as necessary. It can be monitored via circuit 177.
  • the output of the monitor PD101 is also made available for automatic power control. That is, the actual light emission output of the LD 100 is monitored by the PD 101, and whether or not the current corresponding to the monitored light emission output is smaller or larger than the reference potential Vref corresponding to the required light emission output is determined by the comparator 113. Then, according to the determination result, the bias current flowing to the LD 100 via the transistor Tr 1 is increased or decreased.
  • Reference numeral 115 denotes an APC control circuit for forming a reference potential Vref.
  • the actual emission output of the LD 100 is monitored by the PD 101, and the average value of the current corresponding to the monitored emission output and the average value Initialize the reference potential Vref based on the average value (mark rate) of the amplifier AMP input signal.
  • the auto power control is supplementary to the bias current control based on the output of the D / A 176.
  • bias current control is performed based on the output of the D / A 176
  • feedback control by the above-described auto power control is performed repeatedly, assuming that a required light emission output cannot be obtained. .
  • feed power control by auto power control is required. It is desirable to keep the control amount of the system (the amount of increase or decrease of the bias current) relatively small.
  • the CPU 170 monitors the output current of the PD 101 via the A / D 177, compares the actual light output of the LD 100 with the target light output of the LD 100, and sets the actual light output to the target light output. For example, it is possible to detect a state that is lower than a predetermined value.
  • the CPU 1710 monitors the bias current actually flowing to the transistor Tr 1 via the A / D 177, and compares the monitored current value with the bias current to be passed to the transistor Trl via the D / A 176. Then, an abnormality in the bias current can be detected based on the difference.
  • the CPU 170 monitors the modulation current actually flowing to the transistor Tr 2 via the A / D 177, and monitors the monitored current and the modulation current to be supplied to the transistor Tr 2 via the D / A 176. And an abnormality in the modulation current can be detected based on the difference.
  • the LD drive control data for the modulation current control and the bias current control for driving the LD 100 is based on the data to be set in D AC 1 and D AC 2 to obtain the target light output.
  • the table structure is provided in a predetermined area of the flash memory 173 of the microcomputer.
  • the microcombiner 170 obtains the ambient temperature in which the optical transmission module 1 is placed from the temperature sensor 112 via the A / D conversion channel ADC 4 when driving the LD 100.
  • the emission output to be output by the optical transmission module 1 has a property that is physically determined according to the communication environment in which it is placed. For example, the operation program of the CPU 170 or an external instruction Alternatively, the CPU 170 is notified by a signal from a circuit such as a dip switch. This allows the CPU 170 to adjust the required light output and the detected ambient temperature.
  • FIG. 7 shows a main flow chart of the drive control of the LD 100 by the CPU 173.
  • the CPU 173 initializes the LD transmission module 1 (ST 1), and then determines whether or not a shirt down instruction has been issued (ST 2).
  • Shutdown refers to forcibly stopping the drive of the LD 100 due to an abnormal operation of the optical transmission module or the like.
  • shutdown is the highest priority interrupt processing on the hardware, and after power-on reset, it is the function that is executed with the highest priority under any circumstances.
  • the determination of the burst transfer mode or the synchronous transfer mode is made based on the transfer mode control data (ST3).
  • the selection state of the selectors 121 and 163 differs depending on which transfer mode is selected.
  • the drive control flow of the LD 100 by the CPU 170 is also changed according to the burst transfer mode or the synchronous transfer mode.
  • the CPU 170 measures the temperature of the optical transmission module 1 by the temperature sensor 112 (ST 4), and obtains a modulation current and a bias current necessary to obtain a required optical output under the temperature.
  • the optical output and the modulation current are monitored via the A / D conversion channel 177 (ST6).
  • the light output When the value is reduced by half with respect to the standard value, an alarm for shutting off the light output is generated (ST 7).
  • an alarm for abnormal modulation current is generated (ST 8).
  • the temperature of the optical transmission module 1 is periodically measured by the temperature sensor 112 using an unillustrated image included in the microcomputer 17 and the like, and the bias current and the bias current corresponding to the temperature are measured. Only when they differ, the LD drive control data for obtaining the modulation current and the bias current is newly set in the D / A conversion channels DAC1 and DAC2 (ST9).
  • FIG. 8 shows a control flow chart of the burst mode by the CPU 170.
  • the 170 measures the temperature of the optical transmission module 1 by the temperature sensor 112 (ST 10), and obtains a modulation current and a bias current required to obtain a required optical output under the temperature. Set one night from flash memory to D / A conversion channels DAC1 and DAC2, and drive LD100 (ST11). After that, in the burst transfer mode, auto power control is not performed. Instead, it is determined whether or not the monitor current has exceeded a predetermined overcurrent b (ST12), and if not, the above process is repeated at predetermined intervals. If it exceeds, the same judgment is performed again (ST13). If the same result is still obtained, the overcurrent b of the criterion is reduced (ST14), and the CPU 170 detects the temperature by the temperature sensor 112.
  • the temperature of the optical transmission module 1 is measured (ST15), and the LD drive control data for obtaining the modulation current and bias current necessary to obtain the required optical output at that temperature from the flash memory to the D / A conversion channel Set DAC 1 and DAC 2 (ST 16) and drive LD 100. This process is repeated until the monitor current becomes smaller than the overcurrent. Once the monitor current is made smaller than the overcurrent, the Based on the overcurrent generated (ST1), the process returns to W and temperature detection (ST10), and the above process is repeated.
  • FIG. 9 shows an example of the shutdown processing (NMI function).
  • the modulation current and the bias current are set to 0 (ST20).
  • it is determined via the PD 100 whether the light output has decreased (ST 21), and thereafter, whether the monitor current has fallen below the predetermined value (ST 21).
  • a shutdown alarm is displayed (ST23).
  • the optical output does not decrease or if the monitor current becomes abnormal at a predetermined value, it is considered that some abnormality has occurred, and the process returns to the process (2) (ST24).
  • the system decoder 18 decodes the command.
  • the system decoder 18 gives an operation mode setting signal to the microcomputer 17 to make the microcomputer 17 appear apparently the same as the flash memory 173, and thereafter, Gives address signal, strobe signal and write data for replacing LD drive control data of flash memory.
  • the LD drive control data to be written and the write address are later supplied via the optical input terminal 0 PIN.
  • the rewrite control program for the flash memory If it is stored in the OM 172 and the CPU 170 is enabled to execute the rewrite control program by an interrupt or the like, the command decoder 18 decodes the LD drive control data rewrite command, and the decoding result An interrupt request corresponding to the above is given to the macro combination 17.
  • the microcontroller 17 branches the CPU 170 to a process corresponding to the interrupt request, whereby the LD drive control data is rewritten according to the ROM rewrite control program.
  • LD drive control data is supplied from pin 0 PIN.
  • the rewriting of the LD drive control data is performed by the CPU 170 in accordance with the rewriting control program of the ROM 172.
  • the operation can be instructed by a method in which the CPU 170 decodes the interrupt request described above or the command supplied from the optical input terminal OP IN and branches the internal processing to rewrite the LD drive control data. .
  • FIG. 10 shows an example of a PDS system as an optical transmission system to which the optical transmission module 1 is applied.
  • NT network terminating device
  • LT is a terminal side circuit (line network).
  • the optical transmission modules 1 are disposed in the network terminating device NT and the sensor side circuit LT, respectively, and the respective optical transmission modules 1 are connected by an optical fiber 10PF.
  • Optical fiber In the middle of the OP F, a star power blur SCP consisting of passive elements is placed, and the optical fiber 10 PF is branched into many directions.
  • the center side circuit LT is connected to the exchange EX via an interface circuit IF.
  • the SLT is an intra-office device consisting of a plurality of transmitter-side circuits LT and an interface circuit IF.
  • the exchange EX is not particularly limited, but is connected to a transit network.
  • the in-station device SLT, the exchange layer EX, and the control circuit CNT constitute a host device HST such as a sensor.
  • the control circuit CNT controls the exchange EX and the office equipment SLT.
  • the control circuit CNT can send control information to a line constituted by the optical fiber OPF via the interface circuit IF and the exchange EX.
  • Such control information includes a command for switching the data transfer mode in the optical transmission module 1 and control information accompanying the command, a command for switching the gain of the preamplifier 14 and control information accompanying the same, and LD drive control. It is data and its rewrite command.
  • the information exchanged via the ⁇ line has information on the destination in the preamble. Even when the command is sent, destination information is added to the transmission information, and any one or more terminal devices can be designated. As a result, the host device HST can intensively change the operation mode ⁇ operation mode of the optical transmission module 1 included in the terminal device NT.
  • an optical transmission system is applied to a telephone, an ISDN, or the like, the system covers a wide range, and the use environment differs depending on the region.
  • the transmission method in the optical transmission module 1 is changed, the reception sensitivity of the optical signal is adjusted by increasing or decreasing the line load, etc. Being able to change the operation mode of the circuit is excellent in that the maintenance of the PDS system can be simplified.
  • the transfer mode switching control means is changed to a circuit for generating the control signals S1, S2 by hardware such as a dip switch. Can be.
  • a method of instructing the switching of the transfer mode which transfer mode is set may be programmed according to the state of a predetermined port of the micro combination.
  • the automatic control is not limited to a configuration using the f3 ⁇ 4d comparator 113 and the APC control circuit 115 from the viewpoint of reducing the number of parts.
  • the data is taken into the microphone opening via the AZD 177 via the AZD 177, and is stored in the flash memory 173, as described later.
  • the data to be set may be compared with LD drive control data having a table structure provided for each ambient temperature, and may be gradually adjusted.
  • the transmission mode is not limited to SONET-SDH or PDS.
  • An optical fiber is laid radially from the single-side device and the central-side device that make each network terminator correspond to the center-side circuit one-to-one, and a remote multiplexing device is installed ahead of the optical fiber.
  • it may be an active doubles in which a transmission medium is wired.
  • it is not necessary to make the auto power control different between the synchronous transfer mode, the bus and the transfer mode.
  • the optical transmission system of the present invention is not limited to telephones and ISDNs, but is naturally applicable to LANs (Local Area Networks) and the like. Industrial applicability
  • the present invention can be widely applied to an optical transmission module that converts an optical signal and an electric signal in optical transmission, and also applied to an optical transmission system such as a PDS in which an optical fiber is introduced into a telephone or ISDN subscriber system. can do.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)

Abstract

L'invention concerne un module de transmission optique (11) comprenant une section émettrice de lumière (10, 11, 12) qui produit des signaux électriques d'entrée après la conversion des signaux électriques en signaux optiques, une section réceptrice de lumière (13, 14 et 15) qui produit des signaux optiques d'entrée après la conversion des signaux optiques en signaux électriques, et un moyen de commande (17) qui commande les sections émettrice et réceptrice de lumière par la sélection d'un mode de transfert synchrone ou d'un mode de transfert par rafales des sections selon que les signaux électriques sont transférés de manière synchronisée conjointement avec des signaux de données et des signaux d'horloge synchrones ou que les signaux électriques sont transférés par rafales à l'exception du signal d'horloge synchrone. Le moyen de commande (17) reçoit de la section réceptrice de lumière de commande, l'information spécifiant le mode de transfert, le mode de transfert synchrone ou le mode de transfert par rafales, et maintient l'information de commande dans une mémoire EEPROM programmable effaçable électriquement (173). Une unité centrale (170) commande les sections émettrice et réceptrice de lumière en mode de transfert synchrone ou par rafales, en fonction de l'information de commande. Ainsi, le mode de transmission d'un système de transmission optique à un système à signaux électriques peut être modifié facilement par une opération simple telle que la réécriture de l'information de commande.
PCT/JP1996/002817 1996-09-27 1996-09-27 Module et systeme pour la transmission optique WO1998013958A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP1996/002817 WO1998013958A1 (fr) 1996-09-27 1996-09-27 Module et systeme pour la transmission optique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP1996/002817 WO1998013958A1 (fr) 1996-09-27 1996-09-27 Module et systeme pour la transmission optique

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WO1998013958A1 true WO1998013958A1 (fr) 1998-04-02

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WO (1) WO1998013958A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005535271A (ja) * 2002-08-02 2005-11-17 フィニサー コーポレイション プログラム可能な信号パラメータを備えた送受信器
JP2006279246A (ja) * 2005-03-28 2006-10-12 Fujitsu Ltd 光伝送装置およびその制御方法
JP2009200585A (ja) * 2008-02-19 2009-09-03 Nec Corp 光送受信装置、その通信方法、及び通信システム
CN101075851B (zh) * 2007-06-22 2010-09-29 华为技术有限公司 光模块传输模式判断方法及装置
US7894723B2 (en) 2007-02-28 2011-02-22 Mitsubishi Electric Corporation Optical transmission control circuit
CN107454703A (zh) * 2016-05-30 2017-12-08 宇瞻科技股份有限公司 发光装置及其控制方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0210942A (ja) * 1988-06-28 1990-01-16 Toshiba Corp ループ式通信方式
JPH03297244A (ja) * 1990-04-16 1991-12-27 Matsushita Electric Ind Co Ltd ループネットワークシステム

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0210942A (ja) * 1988-06-28 1990-01-16 Toshiba Corp ループ式通信方式
JPH03297244A (ja) * 1990-04-16 1991-12-27 Matsushita Electric Ind Co Ltd ループネットワークシステム

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005535271A (ja) * 2002-08-02 2005-11-17 フィニサー コーポレイション プログラム可能な信号パラメータを備えた送受信器
JP4712557B2 (ja) * 2002-08-02 2011-06-29 フィニサー コーポレイション プログラム可能な信号パラメータを備えた送受信器
JP2006279246A (ja) * 2005-03-28 2006-10-12 Fujitsu Ltd 光伝送装置およびその制御方法
US7894723B2 (en) 2007-02-28 2011-02-22 Mitsubishi Electric Corporation Optical transmission control circuit
CN101075851B (zh) * 2007-06-22 2010-09-29 华为技术有限公司 光模块传输模式判断方法及装置
JP2009200585A (ja) * 2008-02-19 2009-09-03 Nec Corp 光送受信装置、その通信方法、及び通信システム
US8290372B2 (en) 2008-02-19 2012-10-16 Nec Corporation Optical transceiver, its communication method, and communication system
CN107454703A (zh) * 2016-05-30 2017-12-08 宇瞻科技股份有限公司 发光装置及其控制方法

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