CN100346365C - Method and apparatus for compensating a photo-detector - Google Patents
Method and apparatus for compensating a photo-detector Download PDFInfo
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- CN100346365C CN100346365C CNB2003801045758A CN200380104575A CN100346365C CN 100346365 C CN100346365 C CN 100346365C CN B2003801045758 A CNB2003801045758 A CN B2003801045758A CN 200380104575 A CN200380104575 A CN 200380104575A CN 100346365 C CN100346365 C CN 100346365C
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Abstract
The method and apparatus for compensating a photo-detector allows both regulation and monitoring of the photo-detector to be performed with a common digital controller. The controller accepts input of monitored operational parameters including received signal strength and temperature. The controller provides as an output a bias control signal which regulates a positive the positive or negative side bias voltage power supply for the photo-detector. The controller maintains the bias voltage to the photo-detector at levels which optimize the gain and signal-to-noise ratios for the photo-detector thereby facilitating the decoding of the received signal over a broad range of signal strengths and temperatures. The controller includes a corresponding digital signal strength and temperature compensators the outputs of which summed with a summer to provide the bias control signal. The digital signal strength compensator also provides as an output a monitor signal a level of which corresponds to the actual signal strength received by the photo-detector after compensation for the variable gain of the photo-detector resulting from the bias voltage level. A transceiver as well as methods and means for monitoring a photo-detector are also disclosed.
Description
Background of invention
1. invention field
The field of the invention relates generally to optical-fiber network, more particularly, relates to photoreceiver.
2. description of Related Art
In communication system, adopt light beam to come transmission information more and more.The demand of communication bandwidth made long-rangely be converted to optical fiber (numeral) with the junction service junction line from copper cash and communicate by letter.The wide spectral characteristics of optical fiber is supported broadband signal with the very high data rates of the thousands of megabits of per second.
In general, light source, be that transmitter is converted to modulated beam of light to numeral or analog electrical signal, and then be delivered to photodetector, be receiver that photodetector then extracts electric signal by optical fiber from institute's receiving beam.Optical fiber can with adopt frequency division multiplexing, time division multiplex or the multiplexing different communication channel sharing of other form.The scope of the transceiver unit spread communication system of opto-electronic conversion is handled in typical optical link utilization between the optical fiber of optical fiber opposite end and Local Area Network.Optical transceiver provides the kilomegabit traffic rate by the short-haul links in long-range transoceanic cable or the urban area.
Typical transmitter is with fixed power level work.The distance range of optical link can be from several meters to hundred kilometers, thereby pay the optical signal level of wide region on photoreceiver.Photoreceiver must accurately and accurately work for institute's receiving optical signals level of wide region.Photoreceiver generally includes the photoelectric detector of positive-intrinsic-negative (PIN) type or avalanche photo diode (APD) type.Two types have different gains and signal-to-noise characteristic, and the both is with running parameter, change as bias voltage and temperature.Two kinds of photoelectric detectors all require to monitor such as parameters such as luminous power that is received and temperature, are in proper range so that guarantee received signal, thereby guarantee receiver being correctly decoded data.The adjusting of gain and signal-to-noise characteristic adopts mimic channel to handle usually, and adopts digital circuit to monitor.
What need is the new mode that is used to regulate and monitor photoelectric detector, and it has avoided the complexity and the expense of prior art method.
Summary of the invention
A kind of method and device that is used to compensate the photoelectric detector of the ingredient that can be used as photoreceiver or transducer disclosed.Compensation makes the adjusting of photoelectric detector and monitoring can adopt the ordinary numbers controller to carry out.Controller acceptance comprises the input of the monitored running parameter of received signal intensity and temperature.Controller provides bias voltage control signal as output, and it regulates the plus or minus end grid bias power supply of photoelectric detector.Controller remains on the gain of optimizing photoelectric detector and the level of signal to noise ratio (S/N ratio) to the bias voltage of photoelectric detector, thereby helps on the signal intensity of wide region and temperature decoding to received signal.Controller comprises: digital signal corresponding intensity compensation device, its export target bias voltage; And temperature compensator, the variation that its output temperature is relevant is to the compensating for variations bias voltage of photo-detector temperature.Totalizer is sued for peace to the output of signal intensity and temperature compensator, thereby the bias voltage control signal that drives grid bias power supply is provided.The digital signal strength compensator also provides monitor signal as output, and its level is corresponding by the actual optical signal intensity that photoelectric detector received after the variable gain of the photoelectric detector of bias level generation with compensation.
In alternative of the present invention, method and device that transceiver and being used to is monitored photoelectric detector also are disclosed and require its rights and interests.
Summary of drawings
From the detailed description below in conjunction with accompanying drawing, those skilled in the art will clearer these and other feature and advantage of the present invention, in the accompanying drawing:
Fig. 1 represents to intercouple to form a plurality of optical transceivers of wide area network (WAN).
Fig. 2 A is the circuit diagram of one embodiment of the present of invention, and wherein the bias compensation circuit of optical transceiver is coupling in the high-end of photodetector.
Fig. 2 B is the circuit diagram of one embodiment of the present of invention, and wherein the bias compensation circuit of optical transceiver is coupling in the low side of photodetector.
Fig. 3 A-B is the detailed circuit diagram of the alternative of the compensating circuit shown in Fig. 2 A.
Fig. 4 A-B is the detailed circuit diagram of the alternative of the compensating circuit shown in Fig. 2 B.
Fig. 5 A is a curve map, and photoelectric detector gain in the expression photoreceiver and sensitivity are to bias voltage.
Fig. 5 B is a curve map, is illustrated in bias voltage offset in a certain photoelectric detector operating temperature range to temperature.
Fig. 5 C is a curve map, and photoelectric detector gain in the expression photoreceiver and sensitivity are the received signal intensity of milliampere to unit.
Fig. 6 is a process flow diagram flow chart, the working temperature of expression compensating circuit response change and received signal intensity and the process carried out.
The detailed description of embodiment
Fig. 1 represents to intercouple to form a plurality of optical transceivers of the light wide area network (WAN) of communicating by letter between a plurality of Local Area Network of processing.LAN 112,132 is expressed as in corporate HQ 100.LAN 162 is expressed as in company warehouse 150.LAN 182 is expressed as in factory of company 170.All LAN are by the link of high-speed light arterial grid.The length of the light section of optical-fiber network can not wait from several meters to several hundred kilometers.At each company position, corresponding LAN is provided to the electronic communication link of networking workstation, server, processing equipment etc.In order to handle the high-bandwidth communication between the LAN, optical transceiver card 110,130,160 and 180 is expressed as and is coupled to LAN 112,132,162 and 182 respectively.These optical transceiver cards are linked at together in the light mode, and form the node of handling the light arterial grid of high-speed communication between the LAN.
In the embodiment shown, each optical transceiver card comprises a pair of dual-port transceiver and router.Each transceiver card constitutes a node of optical-fiber network.These LAN of optical network links.Transceiver card is coupling in the dicyclo topology with ring section 190,192,194,196.Each transceiver is expressed as from any reception of dicyclo and sends optical modulation information.The receiving port of each transceiver and transmit port are coupled to the correspondent section of each ring.Information can be considered to transmit clockwise in a ring of dicyclo, and transmits counterclockwise in another ring.All transceivers are carried out opto-electronic conversion to receiving data, and then are analyzed to determine its destination by the router of integral body.If information is defined as being sent to the LAN that transceiver card is coupled by one of router, then router is unloaded to corresponding LAN with this information from optical-fiber network.
Light-card 110 comprises two transceivers 118,120 and router one 14.Router one 14 is by LAN interface 116 and LAN 112 couplings.Transceiver via corresponding transmission and receiving port to being coupled to the corresponding network section that forms two ring of light topologys.Fiber optic cables 126 and 124 are via ring section 196 transmission and the reception of the information between the processing circuitry card 110 and 180 respectively.Another is to transmission and the reception of fiber optic cables (not shown) via the information between the ring section 190 processing circuitry cards 110 and 130.The monitoring of transceiver 118-120 is carried out via monitoring interface 122.
Light-card 130 comprises two transceivers 138,140 and router one 34.Router one 34 is by LAN interface 136 and LAN 132 couplings.Transceiver via corresponding transmission and receiving port to being coupled to the corresponding network section that forms two ring of light topologys.The fiber optic cables (not shown) is via the transmission and the reception of the information between the ring section 192 processing circuitry cards 130 and 160.The monitoring of transceiver 138-140 is carried out via monitoring interface 142. Line cards 160 and 180 adopts ring section 194 coupled to each other.
The monitoring of the receiver section of each transceiver and adjusting adopt the ordinary numbers controller to carry out.Controller remains on the gain of optimizing photoelectric detector and the level of signal to noise ratio (S/N ratio) to the bias voltage of the photoelectric detector of receiver part, thereby helps on the signal intensity of wide region and temperature the decoding to received signal.The digital signal strength compensator also provides monitor signal as output, and its level is corresponding with the actual reception signal intensity on the receiver.The receiver monitoring is used for diagnosis or protectiveness maintenance purpose, for example determines to change the time of assembly according to monitored parameter.Assembly wears out or stage life cycle can be determined according to monitored parameter, thereby assembly was replaced before being out of order.
Fig. 2 A is the circuit diagram of one embodiment of the present of invention, and wherein optical transceiver 118 (referring to Fig. 1) has transmitter 200, receiver 220 and compensating circuit 250.Transmitter 200 comprises: one or more differential signal input 206-208 are used to come the high-speed digital data input of auto-correlation LAN; And photodiode 202, it is sent to the corresponding optical fiber 126 of forming optical network segment to the light beam 204 that adopts the high-frequency data modulation.
Receiver comprises photoelectric detector 232, and it is coupled to optical-fiber network in the light mode via optical fiber 124, so that from wherein receiving the optical modulation information carrying signal.In one embodiment of the invention, photoelectric detector comprises positive-intrinsic-negative (PIN) or avalanche photo diode (APD).PIN is with 5 volts of bias level work, and APD can be operated in the 40-60 volt.The signal intensity of institute's receiving beam can change between the 4-6 order of magnitude, shown in light beam 234 and 236.In the embodiments of the invention shown in Fig. 2 A, the negative electrode of photoelectric detector is coupled to the input end as the transimpedance amplifier 226 of the current sink work of photoelectric detector.TIA has the wide dynamic range of performance and the unusual linearity.Typical telecommunications application requirements TIA for scope from less than 0.01 μ A until the input current of 2.5mA keeps linear transimpedance characteristic.The electric data of high frequency modulated and amplification are exported in impedance matching and via the AC coupling mechanism 214 and the differential signal circuit of the remainder AC coupling of receiver circuit from TIA.In the embodiment shown, the AC coupling mechanism comprises carrier coupling capacitor 220-222, they with connect and the common impedance matching networks of forming of resistance 224,216,218 of parallel coupled.The difference output of AC coupling mechanism is through any rearmounted amplification the in the amplifier 212, and the signal after the opto-electronic conversion is exported to remainder, for example router one 14 (referring to Fig. 1) that receives path circuitry on one or more signal line 238-240 by receiver.
Compensating circuit 250 is coupling in the high-end of receiver, so that regulate and monitor the receiver section of transceiver.Compensating circuit remains on the gain of optimizing photoelectric detector and the level of signal to noise ratio (S/N ratio) to the bias voltage of photoelectric detector 232, thereby helps on the signal intensity of wide region and temperature the decoding to received signal.Compensating circuit also provides the monitor signal 290 as output, and its level is corresponding with the actual reception signal intensity on the receiver.Compensating circuit comprises current sensor 276.
The complexity of current sensor can change to current mirror from series coupled resistor.Current sensor provide as output with the proportional low frequency signal of received signal intensity.In resistor embodiment, this low frequency signal is corresponding with the voltage drop at resistance two ends.In current mirror embodiment, current mirror has two branches, is called photoelectric detector branch and mirror image branching again, transmits photodetector currents " Ip " and image current " Im " by them respectively.Image current provides and the proportional low frequency signal of received signal intensity.It is the voltage source node 278 of variable DC power supply 270 in the example shown that two branches of current mirror are coupled at anode.The control branch of current mirror is via the anode coupling of circuit 280 with photoelectric detector 232.In the example shown, supply voltage is controllable between the 30-60 volt, and photoelectric detector is APD.In alternative of the present invention, can adopt the photoelectric detector of PIN type, the corresponding for example 3-5 volt that is reduced to of mains voltage level wherein.The mirror image branching 282 of current mirror provides image current Im, and its level is corresponding with institute's receiving optical signals level that photoelectric detector detects.In the embodiment shown, Im monitors by converting to the proportional voltage of electric current at monitoring node 284 places.This realizes by monitoring node is coupled to electric absorption device 286 with resistance mode.The resistor 274 that monitoring node is coupled to ground is used for carrying out this function.Monitoring node 284 is coupled to the input end of operational amplifier 268.268 of operational amplifiers offer modulus (A/D) converter 266 with the proportional amplification output of image current.The digital value corresponding with image current offers digitial controller 252 by A/D.Digitial controller also receives the corresponding digital value of the temperature with photoelectric detector 232 as input.Temperature sensor 272 detects photo-detector temperature, and corresponding signal is offered A/D converter, and A/D converter offers controller 252 to the respective digital value again.
Controller can adopt processor, microcontroller, programmable logic array (PLA), field programmable logic array (FPLA) (FPGA), special IC (ASIC) or can realize that any logic of state machine realizes.In one embodiment of the invention, controller comprises current compensator 254 and temperature compensator 256.
Current compensator receives the digital value corresponding with monitored photodetector currents as input.Current compensator comprises form and/or formula 260, is used for bias voltage target levels V
tN and monitored current level I
InRelevant, the minimum and maximum monitored current level when comprising with the bias voltage transformation between the target level about occurring.Tables/formulas is also relevant with the gain scaled value target bias, is used for being converted to the photodetector currents level of sensor institute sensing corresponding with the receiving optical signals intensity at photoelectric detector place.Current compensator also comprises storer 262, is used to store historical bias voltage target levels.Each new numeral input that the current compensator handle is corresponding with monitored current level is converted to actual current level.This conversion is determined by determine history registers, the gain scaled value that is called the target bias the storer 262 and is used for that target bias again from tables/formulas 260.Actual reception light signal strength on the photoelectric detector is divided into the current sensor level by the scaled value that will gain and determines.Current compensator is exported the signal corresponding with the actual reception light signal strength on circuit 290.
The digital value corresponding that temperature compensator 256 receives as input with monitored photo-detector temperature.Temperature compensator comprises form or formula 264, and it is relevant with monitored temperature Tp d bias voltage offset.When each of carrying out photoelectric detector newly determined, corresponding bias voltage offset adopts to be determined from the parameter of tables/formulas 264.Temperature correlation to bias voltage is offset by the difference of the reference temperature of penalty coefficient k (volt/degree centigrade) when multiply by Current Temperatures and calibrating receiver is determined.Income value is outputed to all the other inputs of totalizer 258 by temperature compensator.Totalizer is from the bias voltage of current compensator and bias voltage offset addition from temperature compensator.The gained sum is corresponding with required bias level.The signal from totalizer corresponding with required bias level offers variable DC power supply 270 as input.The output of variable DC power supply provides corresponding bias voltage to photoelectric detector 232.
Fig. 2 B is the circuit diagram of one embodiment of the present of invention, and the compensating circuit 250 of optical transceiver wherein is coupling in the low side of photoreceiver 210, so that monitoring received signal intensity.Receiver comprises photoelectric detector 232, is coupled to optical-fiber network in the light mode via optical fiber 124, so that from wherein receiving the optical modulation information carrying signal.In one embodiment of the invention, photoelectric detector comprises positive-intrinsic-negative (PIN) or avalanche photo diode (APD).The signal intensity of institute's receiving beam can change between the 4-6 order of magnitude, shown in light beam 234 and 236.In the embodiments of the invention shown in Fig. 2 B, the anode of photoelectric detector is coupled to the input end as the transimpedance amplifier 226 of the current source work of photoelectric detector.TIA in scope from having wide dynamic range and unusual linearity performance up to the electric current of 2.5mA less than 0.01 μ A.The Vsource input end 230 of TIA is coupled to the variable DC power supply 270 of network component by way of compensation.The Vsink input end 228 of TIA is coupled to the voltage absorber of level less than power level.TIA offers the anode that it imports the photoelectric detector that is coupled to electric current.The electric data of high frequency modulated and amplification output to AC coupling mechanism 214 from TIA on the differential signal circuit.The output of AC coupling mechanism process in post amplifier 212 is amplified.One or more high-frequency data output 238-240 are coupled in the output of post amplifier.
Compensating circuit 250 is coupling in the low side of receiver, so that the measured received signal intensity of monitoring photoelectric detector 232.Compensating circuit comprises current sensor 276.Current sensor can be realized by various parts, comprise resistors in series and current mirror.In current mirror was realized, current mirror had two branches, is called photoelectric detector branch and mirror image branching again, transmitted photodetector currents " Ip " and image current " Im " by them respectively.Two branches of current mirror are coupled on the node 278 at negative terminal, are the voltage absorber on simulation ground in the example shown.The control branch of current mirror is via the negative electrode coupling of circuit 280 with photoelectric detector 232.The mirror image branching 282 of current mirror provides image current Im on circuit 282.The level of image current is corresponding with the receiving optical signals level that photoelectric detector is detected.In the embodiment shown, Im monitors by converting to the proportional voltage of electric current at monitoring node 284 places.This is by being coupled to monitoring node power supply, realizing as the resistor 274 of Vcc=5 volt.Monitoring node 284 is coupled to the input end of operational amplifier 268.The operational amplifier handle offers modulus (A/D) converter 266 with the proportional amplification output of image current, and it provides corresponding digital output to controller 262.Temperature sensor 272 provides another input via A/D converter to controller.Controller 262 receives the digital signal input corresponding with monitored temperature and mirror current levels, and carries out above-mentioned bias adjustment and monitoring function in electric current and temperature compensator.Total output from electric current and temperature compensator 254,256 is used for driving variable DC power supply 270 respectively.Actual current level is exported on signal line 290 by current compensator.
Fig. 3 A-B is the compensating circuit shown in Fig. 2 A, is the detailed circuit diagram of alternative of the part of its current mirror 276 in particular.Current mirror comprises a pair of back-to-back bipolar transistor 302 and 304 that is configured to current mirror.Photodetector currents Ip is flow through therein with reference to 320 in photoelectric detector (Pd) branch 330 of sensing transistor 302 definition current mirrors.Image current Im is flow through therein with reference to 322 in mirrored transistor 304 definition monitoring branches 332.The base stage of sensing and mirrored transistor is coupled to each other, and is coupled to the collector of mirrored transistor.In the high-end embodiment shown in Fig. 3 A-B, sensing and mirrored transistor comprise ' pnp ' type bipolar transistor.
Transistor 302-304 is undesirable to the performance of the current mirror of independent composition, because the image current Im that these transistorized combinations produced is restricted to the upper limit of 5 orders of magnitude for actual purpose.Even in that scope, the current mirror that sensing and mirrored transistor are formed separately is extremely nonlinear.Ip is different with the absolute size of Im on this scope, for example surpasses 75% difference; And the linear difference of the relative size on this scope, for example 10% changes.
The Ebers-Moll model of bipolar transistor provides understanding and the quantification to nonlinear source, and illustrates in following formula 1:
Formula 1:
Wherein Ic is a collector current, and Vbe is the base-emitter voltage drop, and Io is the reverse leakage current from the emitter to the base stage, and c is the base unit of electric charge, and k is a Boltzmann constant, and T is absolute temperature (unit is Kelvin).By typical doping level, minimum by the leakage current that " intrinsic " behavior of pure semiconductor produces, and second-Io can ignore, and provides the simple index number correlativity of Ic to Vbe.
The expansion for Ebers-Moll that must consider in current mirror is an early effect.Early effect is described the proportional variation with the base-emitter voltage of the bipolar transistor of the variation appearance of collector emitter voltage.Non-linear between image current and the photodetector currents produced by the difference of two transistorized collector-emitter voltage drop and the difference of following of two transistorized base-emitter voltages because of early effect.
The collector emitter voltage difference can be 40 volts in APD, and can be 4 volts in PIN realizes.Sensing transistor is subjected to 0.7 volt pressure drop usually, and mirrored transistor then is subjected to equaling in fact the pressure drop of full supply voltage.Collector current in sensing and the mirrored transistor is extremely responsive to the difference of the base-emitter voltage between two transistors.Difference in the base-emitter pressure drop between sensing and the mirrored transistor produces essence and the nonlinear difference between image current and the photodetector currents.
In order to reduce the difference in the collector-emitter voltage drop between each of 302,304 pairs in transistor, non-linear isolation element is introduced into mirror image branching, one of them terminal is coupled to the collector of mirrored transistor 304, and another terminal is coupled to mirror nodes 284.Suitable non-linear isolation element comprises: Shi Mite or Zener diode, field effect transistor and bipolar transistor.Each of these non-linear isolation element presents non-linear voltage drop between at least two terminals with the variation level of image current.Pressure drop between at least two terminals is irrelevant with image current in fact.By reduce between sensing and the mirrored transistor the collector emitter voltage difference and thereby reduce the base-emitter voltage difference, this specific character is improved the consistance between image current and the photodetector currents.Therefore, reduced the difference of the performance that produces because of early effect in fact.
Consistance is defined as the merchant of Ip/Im.In the embodiment shown in Fig. 3 A, non-linear isolation element is a bipolar transistor 306, and emitter terminal wherein is coupled to the collector of mirrored transistor, and collector coupled is to monitoring node 284.Base stage is coupled to the collector of sensing transistor 302 via signal line 312.The consistance of this current mirror during APD realizes is shown in the lines 520 of Fig. 5.
Fig. 3 B represents an alternative of high-side current mirror 276, and wherein, another non-linear isolation element is added to the photoelectric detector branch between sensing transistor 302 and the photoelectric detector 242.Suitable non-linear isolation element comprises: Shi Mite or Zener diode and bipolar transistor.In the embodiment shown in Fig. 3 B, non-linear isolation element is a bipolar transistor 308, and emitter terminal wherein is coupled to the collector of sensing transistor, and collector coupled is to photoelectric detector 242.Base stage is coupled to the collector of sensing transistor 302.The consistance of this current mirror during APD realizes is shown in the lines 530 of Fig. 5.
In the embodiment shown in Fig. 3 A-B, the emitter of sensing and mirrored transistor is coupled to voltage source 278 via resistor 300.This resistor is suitable for the embodiments of the invention that wherein photoelectric detector comprises the APD type.Resistor 300 provides the intensity of relative institute receiving optical signals oppositely to change the function of supply voltage.Therefore, the supply voltage of current mirror reduces along with the increase of light signal strength, thereby improves the performance of APD.It is unwanted that this resistor adopts in one embodiment of the present of invention of PIN type photo-detector therein.
Fig. 4 A-B is the detailed circuit diagram of the alternative of the compensating circuit shown in Fig. 2 B, and wherein, compensating circuit 260 is coupling in the low side of receiver, so that the measured received signal intensity of monitoring photoelectric detector 242.Compensating circuit comprises current mirror 276.Current mirror shown in Fig. 4 A-B is similar to shown in Fig. 3 A-B respectively, and only transistor is that ' npn ' is ambipolar, and the sensing wherein and the emitter-coupled of mirrored transistor are to voltage absorber, and monitoring node 284 is coupled to voltage source by resistor 274.
Fig. 5 A is a curve map, represents for the typical APD type photo-detector with high-end photoelectric detector bias circuit photoelectric detector gain 500 and 502 pairs of bias voltages of sensitivity in the photoreceiver.Actual value on the various curves only provides as an example.To produce similar gain and sensitivity curve for the low side photo-detector bias circuit with different magnitudes of voltage.
The gain trace 500 of APD multiple from the multiple of M=2.5 to M=6.0 on 30 to 55 volts bias voltage scope produces.The gain scaled value is relevant the photodetector currents level by current sensor institute sensing on the receiving optical signals level 234-236 of institute on the APD and the level that is transmitted to controller at it.The gain scaled value can be greater than or less than 1.Sensitivity curve 502 expression APD present the optical signal level in the time of can accepting signal to noise ratio (S/N ratio).The sensitivity of APD presents than flat profile on two zones of different 504-506.These zones first, be in the low sensitivity region 504, APD presents-photoelectric response of 12dBm for the bias voltage between the break-through on 36 volts to 46 volts.Second of these zones, be in the high sensitivity zone 506, APD presents-photoelectric response of 18dBm for the bias voltage between the puncture on 48 volts and 51 volts.Higher or than low sensitivity region in, any increase of gain all recently is offset by reducing noise.Higher and than low sensitivity region between, between for example 46-48 volt bias level, sensitivity makes any of signal to noise ratio (S/N ratio) of photoelectric detector reduce to become inessential along with the photoelectric detector gain increases and improves.At high input signal level place, the APD bias voltage need be reduced to lower bias level V
tLower (for example 46 volts) is so that reduce the sensitivity of APD and avoid that TIA's is saturated.At the low input-signal level, the APD bias voltage need rise to higher bias level V
tUpper (for example 48 volts) so that increase the sensitivity of APD and improve signal to noise ratio (S/N ratio), thereby allows receiver being correctly decoded data.For example 46 volts low sensitivity region high-end and for example the selection of the target bias voltage level on 48 volts the low side of high sensitivity zone allow the working range of whole receiver to expand to five orders of magnitude.High and low target voltage range can rule of thumb be calculated or determine by the actual measurement to exemplary photodetector.
Fig. 5 B is the curve map with curve 510, expression for the bias voltage offset of a certain photoelectric detector operating temperature range to temperature.Calculate as first approximation, normally reverse linear is relevant with the APD bias level for temperature.When the temperature of APD increased, bias voltage must increase to keep identical gain characteristics.Represented 0.05 volt every degree centigrade variation.Skew relative reference temperature T
RefDetermine reference temperature T
RefIt is the uniform temp of being got when determining correlativity between reality and the monitored current level for photoelectric detector.
Fig. 5 C is the curve map with curve 520, and photoelectric detector gain in the expression photoreceiver and sensitivity are the received signal intensity of milliampere to unit.From the monitored current level of 0.0001ma to 0.2ma, the bias voltage 522 of anode biasing APD is V
tUpper (for example 48 volts).From the monitored current level of 0.3ma to 10ma, the bias voltage 528 of anode biasing APD is V
tLower (for example 46 volts).Between 0.2ma-0.3ma, bias level will be determined according to the bias voltage historical record.The digital historical record of bias voltage is used for digital form hysteresis being offered transformation between height and the low target bias voltage regions.Lagging behind adopts the ongoing transformation part of the positive and negative 524-526 of target bias voltage curve 520 to represent with graphics mode respectively.
Fig. 6 is a process flow diagram flow chart, the working temperature of expression compensating circuit response change and received signal intensity and the process carried out.After initialization 600, control goes to procedure 602, therein, and bias voltage target levels V
tN and monitored current level I
InRelevant form and/or function and gain scaled value are loaded into (referring to Fig. 2 A-B reference 260) in the electric current correlator.These tables/functions comprise the minimum and maximum monitored current level when occurring between height and the low target changing.Subsequently, in process 604, bias voltage offset and monitored temperature T
PdRelevant form and/or function are loaded into (referring to Fig. 2 A-B reference 264) in the temperature correlation device.Then, at process 606-608, bias voltage and bias voltage history register are set to low bias voltage target V respectively
tLower.Control goes to procedure 610 then.
Next group process 610-616 determines actual reception optical signal level 234-236.At process 610-612, monitored current level I
InAnd current bias voltage target levels is determined respectively.Then in process 614, bias voltage target is relevant with value in table/function 260 (referring to Fig. 2 A-B), so that determine the current gain scaled value.In process 616, the actual received light signal strength is by determining the sensor light photodetector current level that is delivered to current compensator 254 divided by the gain scaled value in the relevant tables/functions 260 subsequently.Output merchant on signal line 290.(referring to Fig. 2 A-B)
Next group process 618-628 handles the compensation to the bias voltage target of different received current level.According to the bias voltage target historical record in the storer 262 and from the monitored current level of current sensor 276 (referring to Fig. 2 A-B), whether suitably determine for the conversion of bias voltage target.In decision process 618, set for previous bias voltage and to be in height or low level is determined.Be in low level if previous bias voltage is set, then control forwards decision process 624 to.Be in high level if previous bias voltage is set, then control forwards decision process 620 to.
For low bias level, whether surpass the minimum value of being stored in the process 602 in decision process 624 for monitored current level and determine.If like this, then in process 622, target bias remains on low level, afterwards the renewal of carrying out the bias voltage historical record in process 628.Perhaps, in decision process 624, if monitored electric current less than minimum value, is then controlled and gone to procedure 626, therein, bias voltage target is reset and is high-voltage level, thereby improves the sensitivity of receiver.Upgrade the bias voltage historical record in process 628 subsequently.
For high bias level, whether surpass the maximal value of being stored in the process 602 in decision process 620 for monitored current level and determine.If like this, then in process 622, target bias is reset and is low level, thereby reduces the sensitivity of device.Upgrade the bias voltage historical record in process 628 subsequently.Perhaps, in decision process 620, if monitored electric current less than maximal value, is then controlled and gone to procedure 626, therein, bias voltage target remains high-voltage level, upgrades the bias voltage historical record subsequently in process 628.
The effect of process 618-628 is, when the photodetector currents level surpasses maximum photodetector currents level, the output of current compensator is transformed into the low target bias voltage from high target bias, and drop to when being lower than minimum current level when the photodetector currents level, be transformed into high target bias from the low target bias voltage, thereby between photodetector currents level and target bias voltage level, present hysteresis.
Next group process 632-636 handles the compensation to the bias voltage target of different temperature grade.In process 632, determine the temperature of photoelectric detector.In process 634, adopt the parameter of uploading in process 604 that monitored temperature is determined required bias voltage offset then.To the skew of the temperature correlation of bias voltage, for example+/-the # volt determines by the difference that penalty coefficient k (volt/degree centigrade) be multiply by the reference temperature of Current Temperatures and calibrating receiver.Income value is used for being adjusted at the bias voltage target levels of determining among the process 618-628 in process 636.Then, control turns back to process 610 via splicing frame 638, is used for next round electric current and temperature compensation.
Provide the above description of the preferred embodiments of the present invention to be used for explanation and description.Not to be intended to contain various aspects of the present invention or the present invention is limited to disclosed exact form.Obviously, many modifications and changes are that those skilled in the art is perfectly clear.Scope of the present invention is intended to be defined by following claim and equivalent thereof.
Claims (21)
1. device that is used to compensate photoelectric detector, described device comprises:
Sensor is configured to be coupled to described photoelectric detector so that its relevant temperature and current level to be provided;
Controller is coupled to described sensor, is used for relevant with bias voltage offset and relevant current level and target bias from described sensor photo-detector temperature; And
Variable power supply is coupling between described controller and the described photoelectric detector, makes response for the input from described controller corresponding with described target bias and described bias voltage offset, and provides corresponding bias voltage to described photoelectric detector.
2. device as claimed in claim 1 is characterized in that, described controller also comprises:
Temperature compensator is coupled to described sensor, and relevant with corresponding bias voltage offset from the described photo-detector temperature of described sensor, described bias voltage offset compensates described bias voltage at the variation of the described photo-detector temperature of described sensor institute sensing.
3. device as claimed in claim 1 is characterized in that, described controller also comprises:
Current compensator is coupled to described sensor, and is relevant with corresponding target bias the described photodetector currents level from described sensor.
4. device as claimed in claim 1 is characterized in that, described controller also comprises:
Temperature compensator is coupled to described sensor, and relevant with corresponding bias voltage offset from the described photo-detector temperature of described sensor, described bias voltage offset compensates described bias voltage at the variation of the described photo-detector temperature of described sensor institute sensing;
Current compensator is coupled to described sensor, and is relevant with corresponding target bias the described photodetector currents level from described sensor; And
Totalizer, its output terminal is coupled to described variable power supply, its input end is coupled to described temperature and current compensator, and described totalizer is described bias voltage offset and described target bias addition, and described output terminal provide corresponding with described bias voltage and.
5. device as claimed in claim 1 is characterized in that, described controller also comprises:
Storer is used for storing at least previous target bias;
Tables/formulas, relevant high target bias with maximum photodetector currents level, and relevant the low target bias voltage with minimum light photodetector current level; And
Current compensator, be coupled to described storer and described tables/formulas, and described current compensator is stored in described storer and the described at least previous corresponding value of target bias, and between described high target bias and low target bias voltage, change next target bias, thereby realize in the conversion between target bias lagging behind according to the described photodetector currents level of described value of storing in the described storer and described sensor institute sensing.
6. device as claimed in claim 1 is characterized in that, described controller also comprises:
Storer is used for storing at least previous target bias;
Tables/formulas, relevant target bias with related gain scaled value, be used for being converted to the photodetector currents level of described sensor institute sensing corresponding with the receiving optical signals intensity on the described photoelectric detector; And
Current compensator, be coupled to described storer and described tables/formulas, and described current compensator is stored in described storer and the described at least previous corresponding value of target bias, and by relevant the described value of storing in the storer and determine to determine the actual current level of described photoelectric detector as the described photodetector currents level of described sensor institute sensing described receiving optical signals intensity divided by the merchant of described corresponding gain scaled value with corresponding gain scaled value in the described tables/formulas.
7. optical transceiver comprises:
Transmitter is used for the electricity input is converted to light output; And
Receiver comprises:
-photoelectric detector is used for the light input is converted to analog electrical output;
-sensor is coupled to described photoelectric detector so that its relevant temperature and current level to be provided;
-controller is coupled to described sensor, is used for relevant with bias voltage offset and relevant current level and target bias from described sensor photo-detector temperature; And
-variable power supply is coupling between described controller and the described photoelectric detector, makes response for the input from described controller corresponding with described target bias and described bias voltage offset, and provides corresponding bias voltage to described photoelectric detector.
8. optical transceiver as claimed in claim 7 is characterized in that, described controller also comprises:
Temperature compensator is coupled to described sensor, and relevant with corresponding bias voltage offset from the described photo-detector temperature of described sensor, described bias voltage offset compensates described bias voltage at the variation of the described photo-detector temperature of described sensor institute sensing.
9. optical transceiver as claimed in claim 7 is characterized in that, described controller also comprises:
Current compensator is coupled to described sensor, and is relevant with corresponding target bias the described photodetector currents level from described sensor.
10. optical transceiver as claimed in claim 7 is characterized in that, described controller also comprises:
Temperature compensator is coupled to described sensor, and relevant with corresponding bias voltage offset from the described photo-detector temperature of described sensor, described bias voltage offset compensates described bias voltage at the variation of the described photo-detector temperature of described sensor institute sensing;
Current compensator is coupled to described sensor, and is relevant with corresponding target bias the described photodetector currents level from described sensor; And
Totalizer, its output terminal is coupled to described variable power supply, its input end is coupled to described temperature and current compensator, and described totalizer is described bias voltage offset and described target bias addition, and described output terminal provide corresponding with described bias voltage and.
11. optical transceiver as claimed in claim 7 is characterized in that, described controller also comprises:
Storer is used for storing at least previous target bias;
Tables/formulas, relevant high target bias with maximum photodetector currents level, and relevant the low target bias voltage with minimum light photodetector current level; And
Current compensator, be coupled to described storer and described tables/formulas, and described current compensator is stored in described storer and the described at least previous corresponding value of target bias, and between described high target bias and low target bias voltage, change next target bias, thereby realize in the conversion between target bias lagging behind according to the described photodetector currents level of described value of storing in the described storer and described sensor institute sensing.
12. optical transceiver as claimed in claim 7 is characterized in that, described controller also comprises:
Storer is used for storing at least previous target bias;
Tables/formulas, relevant target bias with related gain scaled value, be used for being converted to the photodetector currents level of described sensor institute sensing corresponding with the receiving optical signals intensity on the described photoelectric detector; And
Current compensator, be coupled to described storer and described tables/formulas, and described current compensator is stored in described storer and the described at least previous corresponding value of target bias, and by relevant the described value of storing in the storer and determine to determine the actual current level of described photoelectric detector as the described photodetector currents level of described sensor institute sensing described receiving optical signals intensity divided by the merchant of described corresponding gain scaled value with corresponding gain scaled value in the described tables/formulas.
13. optical transceiver as claimed in claim 7 is characterized in that, described photoelectric detector also comprises at least one in the following: avalanche photodide photoelectric detector and positive-intrinsic-negative photoelectric detector.
14. a method that is used to compensate photoelectric detector comprises:
The temperature of the described photoelectric detector of sensing and current level;
Relevant with bias voltage offset and relevant photo-detector temperature the current level of sensing in described sense operation and target bias; And
In response to described associative operation, change the bias voltage of giving described photoelectric detector.
15. method as claimed in claim 14 is characterized in that, described associative operation also comprises:
Relevant with corresponding bias voltage offset the described photo-detector temperature of sensing in described sense operation, described bias voltage offset compensates described bias voltage at the variation of described photo-detector temperature;
Relevant the described photodetector currents level of sensing in described sense operation with corresponding target bias; And
Described bias voltage offset and described target bias addition, and to described change operation provide corresponding and.
16. method as claimed in claim 14 is characterized in that, described associative operation also comprises:
At least store previous target bias;
Relevant high target bias with maximum photodetector currents level, and relevant the low target bias voltage with minimum light photodetector current level; And
According to the described previous target bias of in described storage operation, storing and in described sense operation the described photodetector currents level of sensing between described high target bias and low target bias voltage, change next target bias, thereby realize to lag behind in the conversion between target bias.
17. method as claimed in claim 14 is characterized in that, described associative operation also comprises:
At least store previous target bias;
Relevant target bias with related gain scaled value, be used for being converted to the photodetector currents level of described sense operation institute sensing corresponding with the receiving optical signals intensity on the described photoelectric detector; And
Determine as the described photodetector currents level of institute's sensing in described sense operation divided by described receiving optical signals intensity from the merchant of the corresponding gain scaled value of described second associative operation.
18. a device that is used to compensate photoelectric detector comprises:
Be used for the temperature of the described photoelectric detector of sensing and the device of current level;
Be used for relevant with bias voltage offset and the current level of described sensing apparatus institute sensing and the relevant device of target bias photo-detector temperature; And
Be used for changing device to the bias level of described photoelectric detector in response to described relevant apparatus.
19. device as claimed in claim 18 is characterized in that, the described device that is used to be correlated with also comprises:
Be used for the described photo-detector temperature of described sensing apparatus institute sensing and the corresponding relevant device of bias voltage offset, described bias voltage offset compensates described bias voltage at the variation of described photo-detector temperature;
Be used for the described photodetector currents level of described sensing apparatus institute sensing and the corresponding relevant device of target bias; And
Be used for described bias voltage offset and described target bias mutually adduction to described modifier provide corresponding and device.
20. device as claimed in claim 18 is characterized in that, the described device that is used to be correlated with also comprises:
Be used for storing at least the device of previous target bias;
Be used for relevant with maximum photodetector currents level and the relevant device of low target bias voltage and minimum light photodetector current level high target bias; And
Thereby be used for the described photodetector currents level of the described previous target bias of storing and described sensing apparatus institute sensing, the conversion of the next target bias of conversion between target bias realizes the device that lags behind between described high target bias and low target bias voltage according to described memory storage.
21. device as claimed in claim 18 is characterized in that, the described device that is used to be correlated with also comprises:
Be used for storing at least the device of previous target bias;
Be used for target bias relevant with related gain scaled value in case the photodetector currents level of described sensing apparatus institute sensing be converted to described photoelectric detector on the corresponding device of receiving optical signals intensity; And
Be used for determining as the described photodetector currents level of described sensing apparatus institute sensing divided by device from the merchant's of the described corresponding gain scaled value of described second associative operation described receiving optical signals intensity.
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| Application Number | Priority Date | Filing Date | Title |
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| US41616202P | 2002-10-04 | 2002-10-04 | |
| US60/416,162 | 2002-10-04 | ||
| US10/285,264 | 2002-10-30 |
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| CN100446050C (en) * | 2006-07-07 | 2008-12-24 | 中国科学院长春光学精密机械与物理研究所 | An encoder processing circuit for time-sharing photoelectric signal acquisition |
| CN101800605B (en) * | 2010-03-04 | 2014-04-09 | 中兴通讯股份有限公司 | Optical receiver, control device thereof and control method thereof |
| JP5673843B2 (en) | 2011-09-22 | 2015-02-18 | 日本電気株式会社 | Optical power monitoring device, method and program |
| US9157797B2 (en) * | 2013-03-14 | 2015-10-13 | Maxim Integrated Products, Inc. | Avalanche photo diode detector control systems and method |
| CN103259591B (en) * | 2013-04-24 | 2016-02-10 | 深圳市极致兴通科技有限公司 | GPON OLT module RSSI quick sampling circuit |
| CN104596642A (en) * | 2015-01-23 | 2015-05-06 | 北京奥普维尔科技有限公司 | APD (Amplitude Probability Distribution) bias temperature compensation system based on MAX1932 |
| CN108964773B (en) * | 2018-06-06 | 2020-04-21 | 青岛海信宽带多媒体技术有限公司 | Optical module temperature compensation method and device |
| JP7096446B2 (en) * | 2019-02-14 | 2022-07-05 | シグニファイ ホールディング ビー ヴィ | Context correction for wireless signal strength sensing for temperature compensation |
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