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
  • H04B10/66—Non-coherent receivers, e.g. using direct detection
  • H04B10/69—Electrical arrangements in the receiver
  • H04B10/693—Arrangements for optimizing the preamplifier in the receiver
• • 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
  • H04B10/66—Non-coherent receivers, e.g. using direct detection
  • H04B10/69—Electrical arrangements in the receiver
  • H04B10/693—Arrangements for optimizing the preamplifier in the receiver
  • H04B10/6931—Automatic gain control of the preamplifier
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F17/00—Amplifiers using electroluminescent element or photocell
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/04—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only
  • H03F3/08—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light
• • 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
  • H04B10/66—Non-coherent receivers, e.g. using direct detection
  • H04B10/69—Electrical arrangements in the receiver
  • H04B10/693—Arrangements for optimizing the preamplifier in the receiver
  • H04B10/6933—Offset control of the differential preamplifier
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B2210/00—Indexing scheme relating to optical transmission systems
  • H04B2210/07—Monitoring an optical transmission system using a supervisory signal
  • H04B2210/074—Monitoring an optical transmission system using a supervisory signal using a superposed, over-modulated signal

Definitions

• the present invention basically relates to the technical field of optical transmission of signals. More particularly, the present invention relates to a circuit arrangement for receiving optical signals according to the preamble of claim 1 as well as to a corresponding method according to the preamble of claim 14.
• optical or light is understood not only as the range of electromagnetic radiation visible to the eye, extending in a wavelength range from about
• the term light or light-emitting is understood as the entire electromagnetic wavelength or frequency spectrum, including the spectrum not visible to the eye, in particular the l[nfra]R[ed] range
• wavelength range up to about 2,000 nanometers or frequency range down to about 150 terahertz for example a wavelength of about 850 nanometers or a frequency of about 350 terahertz.
• a typical optical communication system (cf. Fig. 1 : typical optical link; Fig. 2: typical optical link signalling) comprises three components:
• a light-emitting element LD for example a laser diode, together with its driver DR, which converts the electrical data logic levels to optical power logic levels;
• a light guide GU for example a fibre, which carries the light
• a light-receiving element PD for example a photodetector, such as a photodiode, together with a transimpedance amplifier TA, which senses the light at the end of the light guide GU and converts the light back to an electrical signal.
• a system typically transmits two-level electrical data pattern V in -data-digitai and recovers a replica two-level electrical data pattern V ou t-data-digitai at the receiver side.
• Light (optical) power levels P-i and P 0 (cf. Fig.
• the current signal l PD generated at the light-receiving element PD has to be converted to a voltage signal.
• An integrator IN in the feedback path FP generates a control signal V int in order to subtract the average input current coming from the light-receiving element PD. This is done in order to generate the zero crossing in the input of a limiter LI.
• the limiter LI acts as a comparator which generates in its output a VHIGH (VLOW) logic level for positive (negative) voltages in its input.
• the automatic gain control block AG controls the transimpedance amplifier gain R in order to keep the amplitude V ou t-data-anaiog to a desired level (for example constant) for different l PD current levels that might occur as input to the transimpedance amplifier TA.
• a status change in the transmitter side could be transmitted to the receiver side. This could be for example a change from EIOS (Electrical Idle Ordered Set - a type of data link layer packet) state to
• EIEOS Electronic Idle Exit Ordered Set
• Another optical link could be dedicated to the new signal. However, this is very costly because extra components and extra power is required. Also in some cases, dedicating a complete extra optical link might not be an option at all.
• a third optical power level P 2 different from P-i and from P 0 is to be transmitted in order to be able to distinguish between the two signals, making a multi-level signalling necessary.
• the object of the present invention is to further develop a circuit arrangement of the above-mentioned type and a method of the above-mentioned type in such a way that a multilevel optical link can be provided.
• a circuit arrangement for receiving optical signals from at least one optical guide comprises:
• At least one light-receiving component for converting the optical signals into electrical current signals
• - at least one transimpedance amplifier being provided with the electrical current signals from the light-receiving component
• At least one automatic gain controller for controlling the gain or transimpedance of the transimpedance amplifier, in particular in order to keep the amplitude of the output of the transimpedance amplifier to a desired, for example constant, level for different levels of the electrical current signals,
• At least one limiter acting as a comparator and generating in its output a logic level for positive or negative voltages in its input
• circuit arrangement works according to the following method for receiving optical signals from at least one optical guide, comprising the steps of:
• At least one second limiter is assigned to the second transimpedance amplifier and to the automatic offset controller.
• the automatic gain controller sets the same gain or same transimpedance for both the transimpedance amplifier and the second transimpedance amplifier by sensing the amplitude of the output of the transimpedance amplifier.
• At least one peak detector circuit is provided for sensing the amplitude of the output of the transimpedance amplifier.
• the peak detector circuit is part of the automatic gain control or is shared between the automatic gain controller and the automatic offset controller.
• the amplitude of the output of the transimpedance amplifier is provided to the input of the automatic offset controller.
• the transimpedance amplifier is at least one multi-stage amplifier.
• the second transimpedance amplifier at least one multi-stage amplifier.
• a short is arranged between the output node of the first stage of the transimpedance amplifier and the output node of the first stage of the second transimpedance amplifier.
• the light-receiving component is at least one photodetector, in particular at least one photodiode.
• the optical guide is at least one fibre.
• the end of the optical guide which is not assigned to the light-receiving component, is assigned to at least one light-emitting component, which is preceded by at least one driver for converting electrical data logic levels into the optical signals.
• the present invention finally relates to the use of at least one circuit arrangement according to the type presented hereinbefore and/or of the method according to the type presented hereinbefore for the optical transmission of data signals and of status signals.
• FIG. 1 in a schematic diagram an example of a circuit arrangement according to the prior art operating according to the method of the prior art
• FIG. 2 in a comparative diagram an example of the prior art signalling of the circuit arrangement of Fig. 1 ;
• FIG. 3 in a schematic diagram a first exemplary embodiment of a circuit arrangement according to the present invention operating according to the method of the present invention
• Fig. 4 in a comparative diagram an exemplary embodiment of the signalling of the circuit arrangement of Fig. 3;
• FIG. 5 in a schematic diagram a second exemplary embodiment of a circuit arrangement according to the present invention operating according to the method of the present invention.
• a signal V in -st a tus-digitai is inputted on the transmitter side.
• V in -st a tus-digitai is a slow signal comprising short pulses widely spaced-in-time.
• the transition rate of V in -st a tus-digitai is significantly low compared to the transition rate of V in _ data _ digita
• . in-status-digitai, together with the high speed signal V in -data-digitai, modulates the transmitted optical signal as shown in the signal listing in Fig. 4 ( optical link signalling according to a preferred embodiment of the present invention).
• the optical power P 2 is chosen to be higher than P-i , such that the received currents l 2 and fulfill the relation l 2 ⁇ 2* .
• the second transimpedance amplifier TA2 can be a copy of the transimpedance amplifier TA, or the second transimpedance amplifier TA2 can be an exactly scaled version of the transimpedance amplifier TA.
• the automatic gain control block AG sets the same gain or same transimpedance R for both the transimpedance amplifier TA and the second transimpedance amplifier TA2 by sensing only the Vout-data anaiog amplitude with of a peak detector circuit, which can be part of the automatic gain control AG or can be shared between the automatic gain control AG and an automatic offset control AO.
• the automatic offset control AO sets the voltage V 0 ff Se t for the second transimpedance amplifier TA2; for example, V 0 ff Se t can be R*(l-
• the value of V 0 ff Se t is independent of l 2 , and the information about its value is extracted only from V ou t-data-anaiog-
• the peak detector circuit can be part of the automatic offset control AO or can be shared between the automatic offset control AO and the automatic gain control AG.
• V ou t- status anaiog is used as the feedback signal for the automatic offset control block AO because the V ou t- status anaiog average value is -V 0 ff Se t-
• the averaging circuit is part of the automatic offset control block AO.
• the link operation during an initial phase, only the high speed V in -data-digitai signal is transmitted.
• the Vin-status-digitai signal is kept low during this phase.
• the automatic gain control AG and the automatic offset control AO outputs settle to their final value.
• the time constant of these two loops is significantly lower than the time distance between the two consecutive pulses on the n-status-digitai signal.
• the V in -st a tus-digitai signal can be transmitted.
• the V ou t-data-digitai signal follows the V in _ dat a-digitai signal.
• V in _ status _ digita i When the V in _ status _ digita i signal is high, the optical power transmitted is always P 2 , independently of the value of the V in -data-digitai signal. As a consequence, V out -data-digitai will be high independently of the value of V in _ dat a-digitai- The V out-s tatus-digitai, as desired, goes high as well.
• a short between the output nodes of the first stage of the first transimpedance amplifier TA and of the first stage of the second transimpedance amplifier TA2 can be provided, as depicted in Fig. 5.
• the slow speed signal can be reliably transmitted by sharing the same physical optical link and using multilevel signalling.
• GND reference potential in particular earth potential or ground potential or zero potential
• transimpedance amplifier TA lin-main input of transimpedance amplifier TA
• LD light-emitting component in particular laser diode
• LI limiter in particular first limiter
• PD light-receiving component in particular photodetector, for example photodiode
• driver DR in-data digitai input, in particular data input, of driver DR
• driver DR in-status-digitai input, in particular status input, of driver DR
• 2S2 further or second stage of second transimpedance amplifier TA2

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Electromagnetism (AREA)
• Power Engineering (AREA)
• Amplifiers (AREA)
• Optical Communication System (AREA)
• Light Receiving Elements (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Control Of Amplification And Gain Control (AREA)

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Related Child Applications (1)

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Citations (6)

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• 2014
  • 2014-04-30 JP JP2016511081A patent/JP6437530B2/ja not_active Expired - Fee Related
  • 2014-04-30 WO PCT/EP2014/058937 patent/WO2014177665A1/en not_active Ceased
  • 2014-04-30 EP EP14722633.6A patent/EP2992628B1/en active Active
• 2015
  • 2015-10-29 US US14/926,862 patent/US9780886B2/en active Active

Patent Citations (6)

Non-Patent Citations (1)

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