CN101984775B - CATV optical receiving module - Google Patents
CATV optical receiving module Download PDFInfo
- Publication number
- CN101984775B CN101984775B CN200880129162.8A CN200880129162A CN101984775B CN 101984775 B CN101984775 B CN 101984775B CN 200880129162 A CN200880129162 A CN 200880129162A CN 101984775 B CN101984775 B CN 101984775B
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- input
- optical
- resistance
- amplifier
- optical power
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- 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
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
- H04B10/25751—Optical arrangements for CATV or video distribution
Abstract
A CATV optical receiving module with wide dynamic range, high linearity and high sensitivity is disclosed. Said optical receiving module is used in the optical receiver of the terminal of CATV optical transmission system. Said optical receiving module comprises a photoelectric conversion unit and a preamplifier unit. The signal of said photoelectric conversion unit is output to said preamplifier unit. Said preamplifier unit is a trans-impedance amplifier, and feedback resistance unit is connected to the input and output end of the amplifier. In said optical receiving module, the feedback resistance unit has the function of voltage negative feedback, and is also the load resistance unit of photocurrent. The impedance of said feedback resistance unit is automatically increased when the input optical power is decreased, is automatically decreased when the input optical power is increased, and has certain dynamic range.
Description
Technical field
The present invention discloses a kind of Optical Receivers, particularly a kind of cable TV fibre optic transmission equipment that is used for, big dynamic, high linear, the high sensitivity CATV Optical Receivers of using in the optical receiver of cable TV signal fiber optic transmission system terminal.
Background technology
The cable TV optical receiver is at fiber optic network (being HFC) and on the horizon Fiber to the home (being FTTH) in using all is one of important component part.But existing optical receiver exists sensitivity low when weak input optical power; And when strong input optical power, problems such as linear difference.Under the market demand promoted, the research that improves the optical receiver performance did not stop.The sensitivity of optical fiber telecommunications system is weighed by the optical link carrier-to-noise ratio.The optical link carrier-to-noise ratio is mainly by three partly carrier-to-noise ratio stacks: the one, and the relative intensity noise carrier-to-noise ratio of optical sender, it and luminous power size have nothing to do; The 2nd, the quantum noise carrier-to-noise ratio that photodiode produces, input optical power reduces 1dB, and it reduces 1dB; The 3rd, preamplifier thermal noise carrier-to-noise ratio, input optical power reduces 1dB, and it reduces 2dB.The optical link carrier-to-noise ratio reduces with input optical power and quickens to reduce, and finally moves closer to preamplifier thermal noise carrier-to-noise ratio, and promptly input optical power reduces 1dB optical link carrier-to-noise ratio and reduces 2dB.As seen weak when going into to lose power, the thermal noise carrier-to-noise ratio of preamplifier is carried in the noise ratio at optical link and is played a major role.
Summary of the invention
At the above-mentioned optical receiver of mentioning of the prior art when the weak input optical power, sensitivity is low, during strong input optical power, shortcomings such as linear difference, the invention provides a kind of new cable TV Optical Receivers that is used for optical receiver, its photoelectric current load resistance with preamplifier adopts and can change its size with the power of input optical power, reducing and automatically increase with input optical power, automatically reduce with the increase of input optical power, thereby change the thermal noise carrier-to-noise ratio of preamplifier, make it reduce 1dB thermal noise carrier-to-noise ratio and reduce to be less than 2dB with input optical power.
The technical scheme that the present invention solves its technical problem employing is: a kind of cable TV Optical Receivers, comprise photoelectric conversion unit and pre-amplifier unit, the photoelectric conversion unit signal exports pre-amplifier unit to, pre-amplifier unit comprises amplifier and feedback resistance element, feedback resistance element is connected across on amplifier input terminal and the output, the increase of the photoelectric current that its described feedback resistance element resistance produces with input light and reducing automatically, the reducing and increase automatically of the photoelectric current that produces with input light.
Described cable TV Optical Receivers, its feedback resistance element is for to have triode in the cross-over connection of fixed value resistance two ends, the emitter of triode is connected with the input of fixed value resistance, the collector electrode of triode is connected with the output of fixed value resistance, and triode is connected with the output of fixed value resistance by base electrode bias resistance.
Described cable TV Optical Receivers, its photoelectric conversion unit are photodiode.
The invention has the beneficial effects as follows: principle of the invention uniqueness, can solve effectively that optical receiver is when weak input optical power in the prior art, sensitivity is low, and during strong input optical power, shortcomings such as linear difference have been improved the performance of optical receiver in the prior art greatly.
The present invention will be further described below in conjunction with the drawings and specific embodiments.
Description of drawings
Fig. 1 is equivalent circuit theory figure of the present invention.
Fig. 2 is circuit theory diagrams of the present invention.
Fig. 3 is amplitude-versus-frequency curve figure of the present invention.
Embodiment
Present embodiment is one of preferred embodiment for the present invention, and other all its principles are identical with present embodiment or approximate with basic structure, all within protection range of the present invention.
Please referring to accompanying drawing 1, accompanying drawing 1 is the equivalent circuit theory figure at inventive point of the present invention place, and photodiode is connected on the signal input part of amplifier as photoelectric conversion unit, and cross-over connection has feedback resistance element R between the signal output part of amplifier and the signal input part
f, feedback resistance element R
fAdopt automated variable resistance, the resistance of feedback resistance element Rf reduces with the increase of input optical power, reducing and increase with input optical power.In the present embodiment for more simple and clear saying something, thereby the control circuit that saves the dc bias circuit of photodiode and amplifier and change the feedback resistance size.Among the figure:
C
T: preamplifier input equivalent capacity.C
T=C
PD+ C
In, C
PDBe the junction capacitance under the photodiode work state, C
InInput capacitance for amplifier.
R
T: the amplifier in equivalent resistance.R
T=R
PD+ R
b+ R
In, R
PDBe photodiode work state junction resistance, R
bBe amplifier in biasing resistor, R
InInput resistance for amplifier.
R
f: amplifier variable feedback resistance unit.
Analyzing accompanying drawing 1 from circuit theory is voltage pure resistance negative feedback amplifier in parallel, can be described as trans-impedance amplifier or trsanscondutance amplifier again.Its effect is that faint photoelectric current is converted to the voltage available signal.The content of relevant trans-impedance amplifier please refer to Zhao Zisen and writes the relevant chapters and sections of " optical fiber communication engineering " book.Here quote related conclusions:
(2) bandwidth of trans-impedance amplifier with
Be directly proportional, with R
fC
TBe inversely proportional to.
(3) trans-impedance amplifier equals unit R at direct current tremendously low frequency section transfer function
f
(4) low-frequency gain of trans-impedance amplifier and bandwidth product equal constant.
According to the above characteristic of trans-impedance amplifier, feedback resistance element R
fWith the Optical Receivers performance following relation is arranged:
1, feedback resistance element R
fDouble action is arranged: being the feedback resistance of amplifier, is again photoelectric current
Load resistance.
2, the bandwidth of expansion trans-impedance amplifier must suitably reduce feedback resistance element R
f
3, increasing the bandwidth of trans-impedance amplifier, is to be cost to reduce gain.
4, to improve trans-impedance amplifier thermal noise carrier-to-noise ratio, feedback resistance element R
fBe the bigger the better, but increase feedback resistance element R
fThe adverse consequences that is produced more seriously is to make carrier combination three jumps clap CTB and carrier combination second order beat CSO deterioration except bandwidth narrows down.This is because in the analog signal channel of existing 550MHz bandwidth, is to produce three rank and the topmost frequency group of second order combination beat from Z1 channel (112.25MHz) to 44 channel image carrier waves of Z37 channel (456.25MHz).If increase feedback resistance element R
f, particularly when input optical power was strong, the level of Low Medium Frequency section was very high, and CTB, CSO are worsened.
5, when losing power when strong, the optical link carrier-to-noise ratio is higher, and preamplifier thermal noise carrier-to-noise ratio is a back burner to the contribution of optical link carrier-to-noise ratio, and guarantees that the high linearity of preamplifier is a main target, so suitably reduce feedback resistance element R
fBe favourable.When input optical power was more weak, preamplifier thermal noise carrier-to-noise ratio rose to main status to the contribution of optical link carrier-to-noise ratio, increased feedback resistance element R
fCan promote the optical link carrier-to-noise ratio, all with input optical power reduce reduce because of each channel output level this moment, can not produce CTB and CSO deterioration problem.
In conjunction with above-mentioned characteristic and conclusion, the present invention designs a great dynamic range, high linear, high sensitivity Optical Receivers, except that the photodiode and transistor and reasonable process of selecting function admirable, the photoelectric current load resistance is feedback resistance element R in the preamplifier
fResistance must be variable.Feedback resistance element R
fResistance reducing and automatically increase with input optical power; Otherwise reduce automatically with the increase of input optical power, and itself and input optical power usage range are adapted, suitable dynamic range is arranged.
Realize that physical circuit schematic diagram of the present invention is please referring to accompanying drawing 2, during concrete enforcement, adopt photodiode PIN to change conversion equipment as the photoelectricity dress, convert behind the signal of telecommunication light signal to input by field effect transistor BG1, triode BG2, the amplifier that triode BG3 cooperates peripheral capacitance resistance to form, through exporting behind the amplifier amplifying signal, cross-over connection has resistance R 7 between the output of amplifier and the input, be parallel with triode BG4 with resistance R 7, in order to narrate conveniently, resistance R 7 is connected the input that an end is defined as resistance R 7 with the preamplifier input, resistance R 7 is connected the output that an end is defined as resistance R 7 with the preamplifier output, the emitter of triode BG4 is connected with the input of resistance R 7, the collector electrode of triode BG4 is connected with the output of resistance R 7, and the base stage of triode BG4 is connected with the output of resistance R 7 by base electrode bias resistance R8.Resistance R 7, triode BG4, resistance R 8 are formed feedback resistance element R
fWhen output end current was big, when promptly input optical power was big, triode BG4 shunting was also big, and that equivalent is feedback resistance element R
fReduce; Otherwise, when output end current hour, i.e. input optical power hour, triode BG4 shunting is also little, equivalence be feedback resistance element R
fIncrease.Can realize feedback resistance element R
fSize change along with the size of input optical power.
The benefit that application the present invention brings is as described below:
The Optical Receivers performance index are measured:
When measuring light receives mould, need the Optical Receivers and the big module of tele-release of suitably gain are formed an optical receiver.This test is amplified through gain Optical Receivers for the big module of PD tele-release of 27dB, output termination frequency spectrograph, and when measuring C/N, C/CTB, C/CSO, the optical receiver output connects frequency spectrograph again by channel filter.Because no equalizer and attenuator in the optical receiver passage, so measurement result is represented the Optical Receivers characteristic truly.Test condition is pressed the category-A test condition.
1, the amplitude-frequency characteristic of optical receiver.
Please referring to accompanying drawing 3, three curves are optical receiver amplitude-frequency characteristics at different received optical powers among Fig. 3.From top to bottom three curves be received optical power be respectively 0dBm ,-3dBm ,-10dBm.Cursor MKr1, cursor MKr12, cursor MKr13, cursor MKr14 represent 100,400,700 respectively, 900MHz.Input optical power remains 900MHz by strong bandwidth to weak receiver as seen from the figure.
Received optical power be 0dBm with-two curves of 3dBm are very similar, output level raises and slightly raises with frequency, promptly is when received optical power by force the time, feedback resistance element R
fResistance reduces automatically, and optical receiver is in low, the low high linearity that helps of Mid Frequency level.When input optical power is very weak be-9dBm, top relatively two lines of following that curve have obvious lifting at low, Mid Frequency, and Here it is when input optical power is very weak, feedback resistance element R
fResistance increases the effect of generation automatically.
2, the variable light current loading of preamplifier slows down the lapse rate of thermal noise carrier-to-noise ratio.
Table (one) output level of light receiver
| -7 | 96.52 | 95.95 | 97.13 | 98.95 |
| -8 | 94.96 | 94.44 | 95.62 | 97.29 |
| -9 | 93.79 | 93.22 | 94.22 | 95.42 |
| -10 | 93.30 | 91.92 | 92.34 | 92.95 |
Table (one) is the output level of input optical power optical receiver when being 0 to-10dBm.Table (two) whenever reduces 1dB for the optical receiver input optical power, and the minimizing value of output level is to be got by calculating by the data in the table ().
Table (two) output level of light receiver lapse rate
In the table (), input optical power is reduced to-10dBm by 0dBm, and corresponding 4ch, Z16, Z30,22ch output level reduce 16.5,17.28,17.96 respectively, 19.15dB.The output level of 4ch, Z16, Z30,22ch is identical with this machine when supposing to have a changeless optical receiver input optical power of photoelectric current load resistance to be 0dBm in addition, when input optical power reduce to-output level of four channels respectively reduces 20dB during 10dBm, as seen input optical power be all-during 10dBm, this machine output level is higher by 3.5 than another difference at 4ch, Z16, Z30,22ch, 2.72,2.04,0.85dB, this difference is also represented the difference of two optical receiver thermal noise carrier-to-noise ratios.If the fixing preamplifier noise factor of photoelectric current load resistance is 5dB, even its noise factor is reduced 2dB again, its thermal noise carrier-to-noise ratio does not have the present invention good yet.Moreover 2dB is fallen in the preamplifier noise factor will be paid very expensive.As seen will promote thermal noise carrier-to-noise ratio under the low light level, except that the preamplifier that adopts the low noise coefficient, the method that increases the photoelectric current load resistance is effective on an equal basis.
Some optical receiver adds automatic gain control between Optical Receivers and the big module of tele-release in addition, and the method and the present invention have principle not: automatic gain control only changes output level of light receiver, can not change preamplifier thermal noise carrier-to-noise ratio.
Table (two) whenever reduces 1dB for the optical receiver input optical power, and the reduction of output level is to be got by the data computation in the table ().By table (two) as seen, lose power and be 0 to-2dBm scope, input optical power whenever reduces 1dB, and output level reduces 2dB, and this is identical with the normal optical receiver; When but input optical power was-6 to-9dBm, the output level decrease was significantly less than 2dB.But input optical power reduces again, thisly slow down effect and can not keep, as table (two) input optical power be-during 10dBm, the output level lapse rate of 22ch rises to 2.47dB, this and setting feedback resistance element R
fThe resistance dynamic range is relevant.
3, three of optical receiver big indexs
The three big indexs of table (three) optical receiver
| -4 | 50.4 | 50.8 | 51.3 | 52.0 | 75.0 | 74.7 | 73.5 | 76.0 | 62.2 | 67.5 | 68.5 | 69.9 |
| -5 | 49.5 | 49.9 | 50.4 | 51.1 | 74.0 | 73.4 | 73.6 | 74.9 | 61.0 | 67.2 | 67.2 | 68.6 |
| -6 | 48.5 | 48.8 | 49.2 | 50.0 | ||||||||
| -7 | 47.4 | 47.6 | 48.0 | 49.0 | ||||||||
| -8 | 46.2 | 46.5 | 46.9 | 47.8 | ||||||||
| -9 | 45.5 | 45.5 | 45.9 | 46.6 | ||||||||
| -10 | 44.8 | 44.7 | 44.9 | 45.4 |
Table (three) is that input optical power is 0 to-optical link carrier-to-noise ratio C/N that 10dBm light is met sb. at the airport, and carrier combination three jumps are clapped than C/CTB and the beat of carrier combination second order than C/CSO three big indexs.
When input optical power is 0dBm, see Table (one) because output level of light receiver is very high, so C/CTB and C/CSO index are relatively poor, though reduce feedback resistance element R
fResistance can improve linear index, consideration is unfavorable to C/N under the low light level, moreover have only the C/CSO of 22ch to be slightly less than 60dB, input optical power is-1dBm and following linear index are all fine, so be input optical power the upper limit that 0dBm is decided to be the optical receiver dynamic range.The optical receiver dynamic range headroom is subject to linear index; The lower limit of dynamic range is subject to the sensitivity of optical receiver, if the optical link carrier-to-noise ratio must not be less than 45.5dB, so input optical power for-9dBm is exactly the lower limit of optical receiver dynamic range.
Table (four) optical link carrier-to-noise ratio lapse rate
| -3 | 0.9 | 1.0 | 0.9 | 0.8 |
| -4 | 0.9 | 0.9 | 0.9 | 0.9 |
| -5 | 0.9 | 0.9 | 0.9 | 0.9 |
| -6 | 1.0 | 1.1 | 1.2 | 1.1 |
| -7 | 1.1 | 1.2 | 1.2 | 1.0 |
| -8 | 1.2 | 1.1 | 1.1 | 1.2 |
| -9 | 0.7 | 1.0 | 1.0 | 1.2 |
| -10 | 0.7 | 0.8 | 1.0 | 1.2 |
Table (five) CGO869 Optical Receivers
Table (four) is the successively decrease lapse rate of 1dB optical link carrier-to-noise ratio of input optical power, is by table (three) data computation.Table (five) is the optical receiver optical link carrier-to-noise ratio C/N (data is from the cable TV technology, and 2005.8 woodss very reach " tentative calculation of optical link carrier-to-noise ratio index ") that the CGO869 Optical Receivers of PHILIPS Co. is formed.The preamplifier of CGO869 Optical Receivers is a gaas fet, thus noise factor less be 5.5dB, another silicon materials Optical Receivers BGO847 of the said firm noise factor is 8.0dB. more greatly
Table (three), table (four) and table (five) contrast, input optical power be 0 to-both C/N of 3dBm and Δ (C/N) very nearly the same, but entering low light level scope promptly-5 to-10dBm scope, the C/N of this Optical Receivers has remarkable advantages than the optical module of PHILIPS Co., and optical link carrier-to-noise ratio lapse rate is also obviously little.Analysis CGO869 is though used device tip, exquisite workmanship only is the slight difference on the principle.
The present invention falls sharply from optical receiver optical link carrier-to-noise ratio when the weak input optical power, and the reason of CTB and the hurried deterioration of CSO is set out when strong input optical power, proposition is designed to the resistance variable size with photoelectric current load in the preamplifier by constant resistance, it is reduced with input optical power and automatically increase, otherwise increase and reduce automatically with input optical power, its resistance has certain dynamic range.The Optical Receivers that has particularly solved the photoelectric current load and be the fixed resistance value type exists, when weak input optical power sensitivity low, and in this conflicting difficult problem of the linear difference of strong input optical power.
Claims (3)
1. cable TV Optical Receivers, comprise photoelectric conversion unit and pre-amplifier unit, the photoelectric conversion unit signal exports pre-amplifier unit to, pre-amplifier unit comprises amplifier and feedback resistance element, feedback resistance element is connected across on amplifier input terminal and the output, it is characterized in that: the increase of the photoelectric current that described feedback resistance element resistance produces with input light and reducing automatically, the reducing and increase automatically of the photoelectric current that produces with input light.
2. cable TV Optical Receivers according to claim 1, it is characterized in that: described feedback resistance element is for to have triode in the cross-over connection of fixed value resistance two ends, the emitter of triode is connected with the input of fixed value resistance, the collector electrode of triode is connected with the output of fixed value resistance, and triode is connected with the output of fixed value resistance by base electrode bias resistance.
3. cable TV Optical Receivers according to claim 1 and 2 is characterized in that: described photoelectric conversion unit is a photodiode.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2008/071068 WO2009140827A1 (en) | 2008-05-23 | 2008-05-23 | Catv optical receiving module with wide dynamic range, high linearity and high sensitivity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101984775A CN101984775A (en) | 2011-03-09 |
| CN101984775B true CN101984775B (en) | 2013-07-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200880129162.8A Expired - Fee Related CN101984775B (en) | 2008-05-23 | 2008-05-23 | CATV optical receiving module |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN101984775B (en) |
| WO (1) | WO2009140827A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106253990B (en) * | 2016-09-05 | 2019-07-16 | 飞昂创新科技南通有限公司 | A kind of high-speed low-power-consumption light transceiving chip |
| CN107147438A (en) * | 2016-09-19 | 2017-09-08 | 国家电网公司 | A kind of portable fiber-optic tester |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2435890Y (en) * | 2000-07-29 | 2001-06-20 | 万军 | Sensitive light receiver for cable TV |
| JP2001196877A (en) * | 2000-01-06 | 2001-07-19 | Mitsubishi Electric Corp | Preamplifier circuit |
| US6778021B2 (en) * | 2002-11-26 | 2004-08-17 | Finisar Corporation | Wide dynamic range transimpedance amplifier with a controlled low frequency cutoff at high optical power |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0230202B2 (en) * | 1981-05-27 | 1990-07-05 | Hitachi Cable | RITOKUKAHENZOFUKUKAIRO |
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2008
- 2008-05-23 CN CN200880129162.8A patent/CN101984775B/en not_active Expired - Fee Related
- 2008-05-23 WO PCT/CN2008/071068 patent/WO2009140827A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001196877A (en) * | 2000-01-06 | 2001-07-19 | Mitsubishi Electric Corp | Preamplifier circuit |
| CN2435890Y (en) * | 2000-07-29 | 2001-06-20 | 万军 | Sensitive light receiver for cable TV |
| US6778021B2 (en) * | 2002-11-26 | 2004-08-17 | Finisar Corporation | Wide dynamic range transimpedance amplifier with a controlled low frequency cutoff at high optical power |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101984775A (en) | 2011-03-09 |
| WO2009140827A1 (en) | 2009-11-26 |
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