CN102130724B - Light automatic gain control circuit used for cable TV network optical receiver - Google Patents
Light automatic gain control circuit used for cable TV network optical receiver Download PDFInfo
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- CN102130724B CN102130724B CN201010617758.1A CN201010617758A CN102130724B CN 102130724 B CN102130724 B CN 102130724B CN 201010617758 A CN201010617758 A CN 201010617758A CN 102130724 B CN102130724 B CN 102130724B
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Abstract
The invention relates to a light automatic gain control circuit used for a cable television network optical receiver, belonging to the technical field of cable televisions. The circuit comprises a detector, a biasing circuit, a first amplifying circuit, an electrical modulation attenuation circuit, a second amplifying circuit, an optical power detection circuit, a comparison circuit, a D/A (Digital to Analog) conversion circuit and an optical power indication circuit, wherein the optical detector is connected with the biasing circuit, the optical power detection circuit and an optical input signal; the first amplifying circuit is connected with the biasing circuit and the electrical modulation attenuation circuit; the second amplifying circuit is connected with the electrical modulation attenuation circuit and used for outputting a ratio frequency signal; the D/A conversion circuit is connected with the electrical modulation attenuation circuit, the optical power indication circuit and the comparison circuit; and the comparison circuit is connected with the optical power indication circuit and the optical power detection circuit. The circuit has the advantages that the circuit can guarantee that the television signal of users is normal; network transformation can be carried out on the premise of basically not considering the optical power to achieve the purpose of fibre-optical to the home; the network structure is simple; and passive transmission can be realized.
Description
Technical field
The present invention relates to a kind of light-operated automatic gain that is applied to cable television network optical receiver and control (AGC AutomaticGain Control) circuit, belong to CATV Technology field, especially the transformation of hybrid fiber coax bilateral network is a kind of based on cable TV optical transmission device.
Background technology
To the end of the year 2009, national wired broadcasting TV user reaches 1.74 hundred million families.On January 13rd, 2010, Premier Wen Jiabao's formal proposition in the Executive Meeting of the State Council of holding accelerates to advance China Telecom's net, broadcasting and television network and the Internet integration of three networks, and the clear and definite timetable of the integration of three networks.June 6 in 2010, ， China passed through integration of three networks pilot scheme, and in July 1 definite Liao12Ge experimental city and area.After the integration of three networks realizes, broadcasting and television network not only can provide TV programme, and the Internet and voice communication service can also be provided.For the Internet and communication network, also can develop better the business such as Web TV, mobile TV, share the abundant program resource of broadcasting and television network.It is basic transmission network transformation that SARFT(The State Administration of Radio and Television) requires one of hybrid fiber/ coax, HFC (HFC) bilateral network transformation, wherein has and substantially realizes Fiber-To-The-Building, and progressively Fiber to the home in realization.Along with continuous upgrading and the transformation of hfc plant, fiber optic network, with cheap price, wider coverage, transmission speed and less failure rate faster, replaces rapidly coaxial cable.In hfc plant, optical sender and optical receiver just become the key equipment in network like this, and here I just receive the light control automatic gain control circuit of cable television network optical receiver according to a ultra-low light power of the Developing of CHINA RFTCOM Co Ltd of new generation.
Summary of the invention
The object of the invention is to provide a kind of light automatic gain control circuit for cable television network optical receiver, it can guarantee that user's TV signal is normal, can under the prerequisite of substantially not considering luminous power, carry out the network rebuilding, realizes fiber entering household, the network architecture is simple, and network is realized passive transmission.
The object of the invention is to reach like this, a kind of light automatic gain control circuit for cable television network optical receiver, it is characterized in that: comprise photodetector, biasing circuit, the first amplifying circuit, electricity is adjusted attenuator circuit, the second amplifying circuit, luminous power testing circuit, comparison circuit, D/A change-over circuit and luminous power indicating circuit, optical fiber passes through flange input optical signal to photodetector, photodetector and biasing circuit, luminous power testing circuit is connected with light input signal, the first amplifying circuit and biasing circuit, electricity adjusts attenuator circuit to connect, the second amplifying circuit adjust attenuator circuit to be connected with electricity and with export radiofrequency signal, D/A change-over circuit is adjusted attenuator circuit with electricity, luminous power indicating circuit is connected with comparison circuit, comparison circuit is connected with luminous power testing circuit with luminous power indicating circuit.
Biasing circuit of the present invention comprises inductance L 2, signal coupler Z1, capacitor C 5～C7, resistance R 3～R5,1 pin of one termination photodetector of inductance L 2, inductance L 2 another termination signal coupler Z1 inputs, one end of signal coupler Z1 output connecting resistance R4 and capacitor C 7, signal coupler Z1 mixes termination the first amplifying circuit, one end of resistance R 4 other end connecting resistance R3, R5 and capacitor C 5, one termination direct voltage+24V of resistance R 5 other ends, capacitor C 6, capacitor C 5, C6, C7, resistance R 3 other end common grounds.
The first amplifying circuit of the present invention comprises capacitor C 3, C4, C8～C10, inductance L 3, L4, resistance R 6, amplifier tube A1, the amplifier tube A1Wei OEI F226 of company wherein, the signal coupler Z1 of one termination biasing circuit of capacitor C 3 mixes end, 1 pin of capacitor C 3 another termination amplifier tube A1 and one end of capacitor C 4, 2 pin of amplifier tube A1 connect one end of capacitor C 8 and inductance L 4, one end of inductance L 4 another termination capacitor C 9 and resistance R 6, resistance R 6 another termination direct voltage+8V and capacitor C 10 one end, one end of capacitor C 8 another termination inductance L 3, another termination electricity of inductance L 3 is adjusted attenuator circuit, capacitor C 4, C9, 3 of the other end of C10 and amplifier tube A1, 4 pin common grounds.
Electricity of the present invention adjusts attenuator circuit to comprise inductance L 5, capacitor C 11～C15, C17, resistance R 7～R14, double diode D1, D2, 3 pin of one end of resistance R 9 and double diode D1 connect the first amplifying circuit, direct voltage+24V connects capacitor C 11, one end of resistance R 7, resistance R 7 other end connecting resistance R10, R11, R12 and capacitor C 14 one end, resistance R 10 another termination capacitor C 12, 1 pin of one end of resistance R 8 and double diode D1, resistance R 12 another termination capacitor C 15, 1 pin of resistance R 13 one end and double diode D2, 2 pin of double diode D1 connect 2 pin of double diode D2 and one end of inductance L 5, 3 pin connecting resistance R14 one end and the second amplifying circuit of double diode D2, inductance L 5 another termination capacitor C 13 one end, capacitor C 17 one end and A point, A point connects D/A change-over circuit, capacitor C 11-C15, the other end of C17, resistance R 8, R9, R11, R13, R14 common ground.
The second amplifying circuit of the present invention comprises capacitor C 16, C18～C21, inductance L 6, resistance R 15, amplifier tube A2, attenuator ATT1, the amplifier tube A2Wei OEI F226 of company wherein, one termination electricity of capacitor C 16 is adjusted attenuator circuit, 1 pin of capacitor C 16 another termination amplifier tube A2, 2 pin of amplifier tube A2 connect one end of capacitor C 19 and inductance L 6, the input of capacitor C 19 another termination attenuator ATT1, the output output radiofrequency signal of attenuator ATT1, another termination capacitor C 18 of inductance L 6 and resistance R 15 one end, resistance R 15 another termination direct voltage+8V, capacitor C 20HeC21 one end, capacitor C 18, C20, 3 of the other end of C21 and amplifier tube A2, 4 pin common grounds.
Luminous power testing circuit of the present invention comprises inductance L 1, resistance R 1, R2, capacitor C 1, C2, one termination photodetector 2 pin of inductance L 1, one end of inductance L 1 other end connecting resistance R1, R2, capacitor C 1, one end of resistance R 1 another termination capacitor C 2 and B point, B point connects comparison circuit, capacitor C 1, C2, resistance R 2 other end common grounds.
Comparison circuit of the present invention comprises capacitor C 26, C27, resistance R 47～R57, amplifier LM1～LM3, capacitor C 27 one end, 2 of amplifier LM1, 6 pin, 2 of LM2, 6, 9, 13 pin, 2 of LM3, 6, 9, the B point of 13 pin connects luminous power testing circuit, the 3 pin connecting resistance R47 of amplifier LM1, R48 one end, 12 pin and resistance R 49 one end of resistance R 48 another termination amplifier LM2, 10 pin and resistance R 50 one end of resistance R 49 another termination amplifier LM2, 12 pin and resistance R 51 one end of resistance R 50 another termination amplifier LM3, 10 pin and resistance R 52 one end of resistance R 51 another termination amplifier LM3, resistance R 52 another termination direct voltage+24V and capacitor C 26 one end, 8 pin of amplifier LM1, 4 pin of LM2, 4 pin of LM3 meet direct voltage+24V, 5 pin and resistance R 53 one end of resistance R 47 another termination amplifier LM1, 3 pin and resistance R 54 one end of resistance R 53 another termination amplifier LM2, 5 pin and resistance R 55 one end of resistance R 54 another termination amplifier LM2, 3 pin and resistance R 56 one end of resistance R 55 another termination amplifier LM3, 5 pin and resistance R 57 one end of resistance R 56 another termination amplifier LM3, 4 pin of amplifier LM1, 11 pin of LM2, the 11 pin ground connection of LM3, capacitor C 27 other end ground connection, 1 pin of amplifier LM1 connects the positive pole of diode D8 and the positive pole of light-emitting diode D18, 7 pin of amplifier LM1 connect the positive pole of diode D13 and the positive pole of light-emitting diode D23, 1 pin of amplifier LM2 connects the positive pole of diode D12 and the positive pole of light-emitting diode D22, 7 pin of amplifier LM2 connect the positive pole of diode D11 and the positive pole of light-emitting diode D21, 8 pin of amplifier LM2 connect the positive pole of diode D6 and the positive pole of light-emitting diode D16, 14 pin of amplifier LM2 connect the positive pole of diode D7 and the positive pole of light-emitting diode D17, 1 pin of amplifier LM3 connects the positive pole of diode D10 and the positive pole of light-emitting diode D20, 7 pin of amplifier LM3 connect the positive pole of diode D9 and the positive pole of light-emitting diode D19, 8 pin of amplifier LM3 connect the positive pole of diode D4 and the positive pole of light-emitting diode D14, the positive pole of the 14 pin diode D5 of amplifier LM3 connects the positive pole with light-emitting diode D15, positive pole by diode D4-D13 is connected with D/A change-over circuit, positive pole by light-emitting diode D14-D23 is connected with luminous power indicating circuit, capacitor C 26, the other end of C27, the other end common ground of resistance R 57.
D/A change-over circuit of the present invention comprises capacitor C 22, C23, resistance R 16～R36, voltage-stabiliser tube D3, diode D4～D13, the positive pole of diode D4～D13 is connected with luminous power indicating circuit with comparison circuit, the negative pole of diode D4～D13 is connecting resistance R27～R36 one end respectively, the other end of resistance R 27～R36 is connecting resistance R17～R26 one end respectively, resistance R 17～R26 other end, resistance R 16 one end, capacitor C 22 one end, the negative pole of voltage-stabiliser tube D3 connects A point, A point connects the A point that electricity is adjusted attenuator circuit, resistance R 16 another termination capacitor C 23 one end, capacitor C 22, the anodal common ground of the C23 other end and voltage-stabiliser tube D3.
Luminous power indicating circuit of the present invention comprises capacitor C 24, C25, resistance R 37～R46, light-emitting diode D14～D23, the positive pole of light-emitting diode D14～D23 is connected with D/A change-over circuit with comparison circuit, the negative pole of light-emitting diode D14～D23 is connecting resistance R37～R46 one end respectively, another termination direct voltage+8V of resistance R 37～R46 and capacitor C 24,C25 one end, capacitor C 24, C25 other end ground connection.
The present invention has used high sensitivity photodetector, when input optical power is during at-5dBm, can guarantee that user's TV signal is normal.Input photodetector luminous power, when-8～+ 2dBm, keeps output level invariable, when carrying out network design, according to the requirement of network output level, can under the prerequisite of substantially not considering luminous power, carry out the network rebuilding.Adopted accurate luminous power indicating circuit, show that luminous power deixis circuit has accurately played the effect of light power meter, can directly read current received optical power, for system maintenance, have great importance, especially for the user who there is no light power meter, there is luminous power indicative significance extraordinary.Make full use of existing network, optical fiber is extended to user side, EPON is completely transparent to signal transfer protocol, format modulation signal, network can be expanded according to the growth of customer volume, user needs higher quality requirement really from now on, can be directly extension of optical fiber to user, realize real fiber entering household.Network using optical fiber, network configuration is very simple, has significantly reduced active electronic equipment between front end and user, and as light station and the power supply of amplifier ，Bu Xu field, the statistics RF PON of AC power supply backup ，Ju operator network can reduce by 90% maintenance than hfc plant.Equipment and number of fibers greatly reduce, and the network architecture is simple and clear, and network is realized passive transmission.
Accompanying drawing explanation
Fig. 1 is block diagram of the present invention.
Fig. 2 is schematic diagram of the present invention.
Embodiment
Referring to Fig. 1, a kind of light control automatic gain control circuit for cable television network optical receiver, comprises that photodetector passes through biasing circuit output electrical signals to the first amplifying circuit, by electricity, adjusts attenuator circuit, through the second amplifying circuit output radiofrequency signal.And photodetector output voltage connects electricity tune attenuator circuit through luminous power testing circuit, comparison circuit, D/A change-over circuit successively, comparison circuit is exported another road to luminous power indicating circuit, completes AGC and controls.
Referring to Fig. 2, photodetector of the present invention is electrooptical device PIN pipe, and optical fiber is by flange input optical signal to photodetector, and 1 pin of photodetector connects biasing circuit, and 2 pin of photodetector connect luminous power testing circuit, 3 pin ground connection of photodetector.Light automatic gain control circuit for cable television network optical receiver is within the scope of certain light receiving power (8～+ 2dBm), the signal of telecommunication of photodetector output is adjusted to attenuator circuit, invariable radiofrequency signal output of the second amplifying circuit output through biasing circuit, the first amplifying circuit, electricity, the D/A change-over circuit of leading up to of comparison circuit is controlled electricity and is adjusted attenuator circuit, and comparison circuit is separately leaded up to luminous power indicating circuit and shown the optical power intensity of current reception.+ 24V direct voltage is through capacitor C 11, C6, resistance R 5, capacitor C 5, resistance R 3, R4, capacitor C 7, signal coupler Z1, inductance L 2 input photodetector 1 pin, photodetector work, 1 pin by photodetector 1 pin output electrical signals through inductance L 2, signal coupler Z1, capacitor C 3, C4 input amplifier tube A1, + 8V direct voltage is input to 2 pin of amplifier tube A1 through capacitor C 10, resistance R 6, capacitor C 9, inductance L 4, amplifier tube A1 work, the signal of telecommunication that 2 pin of amplifier tube A1 amplify is through 3 pin of capacitor C 8, inductance L 3, resistance R 9 input double diode D1; Photodetector 2 pin output voltages, the luminous power testing circuit forming through inductance L 1, resistance R 1, R2, capacitor C 1, C2, output voltage through B point to comparison circuit; Capacitor C 26, C27, resistance R 47～R57, amplifier LM1～LM3 form comparison circuit ，Yi road and output to D/A change-over circuit, and another road outputs to luminous power indicating circuit; Capacitor C 22, C23, voltage-stabiliser tube D3, diode D4～D13, resistance R 16～R36 form D/A change-over circuit and adjust attenuator circuit through A point control electricity; Light-emitting diode D14～D23, resistance R 37～R46, capacitor C 24, C25 form luminous power indicating circuit, show current received optical power intensity; D/A change-over circuit controls voltage to through the output of A point the electricity being comprised of inductance L 5, capacitor C 12～C15, C17, double diode D1, D2, resistance R 7～R14 and adjusts attenuator circuit; The 3 pin output electrical signals of double diode D2 are through 1 pin of resistance R 14, capacitor C 16 input amplifier tube A2, + 8V direct voltage is through 2 pin of capacitor C 21, electrochemical capacitor C20, resistance R 15, capacitor C 18, inductance L 6 input amplifier tube A2, amplifier tube A2 work, the signal of telecommunication that 2 pin of amplifier tube A2 amplify is through capacitor C 19, the output of attenuator ATT1 output radiofrequency signal.A1 wherein, the low noise amplification pipe F226 of A2Wei OEI company, Z1 is signal coupling coil, LM1～LM3 is operational amplifier, D1, D2 is staged decay double diode, D3 is voltage-stabiliser tube, D4～D13 is diode, D14～D23 is light-emitting diode, ATT1 is fixed attenuator, L4, L5 is High frequency filter direct current overcurrent inductance, L1～L3 is that signal flatness is adjusted air core inductor, C4 is signal flatness control capacittance, C17 is tantalum electric capacity, C20 is electrochemical capacitor, C3, C8, C16, C19 is high frequency capacitance, C1, C2, C5～C7, C9～C15, C17, C18, C21～C27 is high-frequency filter capacitor, R9, R14 is impedance matching resistance, R2, R3, R8, R11, R13, R57 is dropping resistor, R1, R4～R7, R10, R12, R15～R56 is current-limiting resistance.
The most attractive benefit of the present invention is likely to reduce network operation cost.When disposing solution, its following points technical advantage:
1. ultra-low light power receives: conventional photodetector input optical power is when-3dBm is following, and carrier-to-noise ratio (C/N) can sharply decline, and causes user's TV signal to occur mosaic.Light automatic gain control circuit has used high sensitivity photodetector, when input optical power is during at-5dBm, can guarantee that user's TV signal is normal.
2. output level is invariable: conventional optical receiver input optical power changes 1dBm, output electrical signals can change 2dB, light automatic gain control circuit in input optical power-8～during+2dBm, pass through internal control circuit, can keep output level invariable, when carrying out network design, according to the requirement of network output level, can under the prerequisite of substantially not considering luminous power, carry out the network rebuilding.
3. luminous power indication: conventional optical receiver only has simple luminous power indication, cannot correctly judge current received optical power.Light automatic gain control circuit has adopted accurate luminous power indicating circuit, show that luminous power deixis circuit has accurately played the effect of light power meter, can directly read current received optical power, for system maintenance, have great importance, especially for the user who there is no light power meter, there is luminous power indicative significance extraordinary.
4. cost is relatively low, be convenient to upgrade expanding: make full use of existing network, optical fiber is extended to user side, EPON is completely transparent to signal transfer protocol, format modulation signal, network can be expanded according to the growth of customer volume, user needs higher quality requirement really from now on, can be directly extension of optical fiber to user, realize real fiber entering household.
5. fail safe, reliability are high, maintainable good: network using optical fiber, network configuration is very simple, between front end and user, significantly reduced active electronic equipment, as light station and amplifier, the power supply of Bu Xu field, the statistics RF PON of AC power supply backup ，Ju operator network can reduce by 90% maintenance than hfc plant.Equipment and number of fibers greatly reduce, and the network architecture is simple and clear, and network is realized passive transmission.
Claims (8)
1.
a kind of light automatic gain control circuit for cable television network optical receiver, it is characterized in that: comprise photodetector, biasing circuit, the first amplifying circuit, electricity is adjusted attenuator circuit, the second amplifying circuit, luminous power testing circuit, comparison circuit, D/A change-over circuit and luminous power indicating circuit, photodetector and biasing circuit, luminous power testing circuit is connected with light input signal, the first amplifying circuit and biasing circuit, electricity adjusts attenuator circuit to connect, the second amplifying circuit adjust attenuator circuit to be connected with electricity and with export radiofrequency signal, D/A change-over circuit is adjusted attenuator circuit with electricity, luminous power indicating circuit is connected with comparison circuit, comparison circuit is connected with luminous power testing circuit with luminous power indicating circuit, described comparison circuit comprises capacitor C 26, C27, resistance R 47～R57, amplifier LM1～LM3, capacitor C 27 one end, 2 of amplifier LM1, 6 pin, 2 of LM2, 6, 9, 13 pin, 2 of LM3, 6, 9, the B point of 13 pin connects luminous power testing circuit, the 3 pin connecting resistance R47 of amplifier LM1, R48 one end, 12 pin and resistance R 49 one end of resistance R 48 another termination amplifier LM2, 10 pin and resistance R 50 one end of resistance R 49 another termination amplifier LM2, 12 pin and resistance R 51 one end of resistance R 50 another termination amplifier LM3, 10 pin and resistance R 52 one end of resistance R 51 another termination amplifier LM3, resistance R 52 another termination direct voltage+24V and capacitor C 26 one end, 8 pin of amplifier LM1, 4 pin of LM2, 4 pin of LM3 meet direct voltage+24V, 5 pin and resistance R 53 one end of resistance R 47 another termination amplifier LM1, 3 pin and resistance R 54 one end of resistance R 53 another termination amplifier LM2, 5 pin and resistance R 55 one end of resistance R 54 another termination amplifier LM2, 3 pin and resistance R 56 one end of resistance R 55 another termination amplifier LM3, 5 pin and resistance R 57 one end of resistance R 56 another termination amplifier LM3, 4 pin of amplifier LM1, 11 pin of LM2, the 11 pin ground connection of LM3, capacitor C 27 other end ground connection, 1 pin of amplifier LM1 connects the positive pole of diode D8 and the positive pole of light-emitting diode D18, 7 pin of amplifier LM1 connect the positive pole of diode D13 and the positive pole of light-emitting diode D23, 1 pin of amplifier LM2 connects the positive pole of diode D12 and the positive pole of light-emitting diode D22, 7 pin of amplifier LM2 connect the positive pole of diode D11 and the positive pole of light-emitting diode D21, 8 pin of amplifier LM2 connect the positive pole of diode D6 and the positive pole of light-emitting diode D16, 14 pin of amplifier LM2 connect the positive pole of diode D7 and the positive pole of light-emitting diode D17, 1 pin of amplifier LM3 connects the positive pole of diode D10 and the positive pole of light-emitting diode D20, 7 pin of amplifier LM3 connect the positive pole of diode D9 and the positive pole of light-emitting diode D19, 8 pin of amplifier LM3 connect the positive pole of diode D4 and the positive pole of light-emitting diode D14, the positive pole of the 14 pin diode D5 of amplifier LM3 connects the positive pole with light-emitting diode D15, positive pole by diode D4-D13 is connected with D/A change-over circuit, positive pole by light-emitting diode D14-D23 is connected with luminous power indicating circuit, capacitor C 26, the other end of C27, the other end common ground of resistance R 57.
2.
light automatic gain control circuit for cable television network optical receiver according to claim 1, it is characterized in that described biasing circuit comprises inductance L 2, signal coupler Z1, capacitor C 5～C7, resistance R 3～R5, 1 pin of one termination photodetector of inductance L 2, inductance L 2 another termination signal coupler Z1 inputs, one end of signal coupler Z1 output connecting resistance R4 and capacitor C 7, signal coupler Z1 mixes termination the first amplifying circuit, resistance R 4 other end connecting resistance R3, one end of R5 and capacitor C 5, resistance R 5 other ends, one termination direct voltage+24V of capacitor C 6, capacitor C 5, C6, C7, resistance R 3 other end common grounds.
3.
light automatic gain control circuit for cable television network optical receiver according to claim 1, it is characterized in that the first described amplifying circuit comprises capacitor C 3, C4, C8～C10, inductance L 3, L4, resistance R 6, amplifier tube A1, the amplifier tube A1Wei OEI F226 of company wherein, the signal coupler Z1 of one termination biasing circuit of capacitor C 3 mixes end, 1 pin of capacitor C 3 another termination amplifier tube A1 and one end of capacitor C 4, 2 pin of amplifier tube A1 connect one end of capacitor C 8 and inductance L 4, one end of inductance L 4 another termination capacitor C 9 and resistance R 6, resistance R 6 another termination direct voltage+8V and capacitor C 10 one end, one end of capacitor C 8 another termination inductance L 3, another termination electricity of inductance L 3 is adjusted attenuator circuit, capacitor C 4, C9, 3 of the other end of C10 and amplifier tube A1, 4 pin common grounds.
4.
light automatic gain control circuit for cable television network optical receiver according to claim 1, is characterized in that described electricity tune attenuator circuit comprises inductance L 5, capacitor C 11～C15, C17, resistance R 7～R14, double diode D1, D2,3 pin of one end of resistance R 9 and double diode D1 connect the first amplifying circuit, and direct voltage+24V connects capacitor C 11, one end of resistance R 7, resistance R 7 other end connecting resistance R10, R11, R12 and capacitor C 14 one end, resistance R 10 another termination capacitor C 12, 1 pin of one end of resistance R 8 and double diode D1, resistance R 12 another termination capacitor C 15, 1 pin of resistance R 13 one end and double diode D2,2 pin of double diode D1 connect 2 pin of double diode D2 and one end of inductance L 5,3 pin connecting resistance R14 one end and the second amplifying circuit of double diode D2, inductance L 5 another termination capacitor C 13 one end, capacitor C 17 one end and A point, A point meets D/A change-over circuit, capacitor C 11-C15, the other end of C17, resistance R 8, R9, R11, R13, R14 common ground.
5.
light automatic gain control circuit for cable television network optical receiver according to claim 1, it is characterized in that the second described amplifying circuit comprises capacitor C 16, C18～C21, inductance L 6, resistance R 15, amplifier tube A2, attenuator ATT1, the amplifier tube A2Wei OEI F226 of company wherein, one termination electricity of capacitor C 16 is adjusted attenuator circuit, 1 pin of capacitor C 16 another termination amplifier tube A2, 2 pin of amplifier tube A2 connect one end of capacitor C 19 and inductance L 6, the input of capacitor C 19 another termination attenuator ATT1, the output output radiofrequency signal of attenuator ATT1, another termination capacitor C 18 of inductance L 6 and resistance R 15 one end, resistance R 15 another termination direct voltage+8V, capacitor C 20HeC21 one end, capacitor C 18, C20, 3 of the other end of C21 and amplifier tube A2, 4 pin common grounds.
6.
light automatic gain control circuit for cable television network optical receiver according to claim 1, it is characterized in that described luminous power testing circuit comprises inductance L 1, resistance R 1, R2, capacitor C 1, C2, one termination photodetector 2 pin of inductance L 1, one end of inductance L 1 other end connecting resistance R1, R2, capacitor C 1, one end of resistance R 1 another termination capacitor C 2 and B point, B point connects comparison circuit, capacitor C 1, C2, resistance R 2 other end common grounds.
7.
light automatic gain control circuit for cable television network optical receiver according to claim 1, it is characterized in that described D/A change-over circuit comprises capacitor C 22, C23, resistance R 16～R36, voltage-stabiliser tube D3, diode D4～D13, the positive pole of diode D4～D13 is connected with luminous power indicating circuit with comparison circuit, the negative pole of diode D4～D13 is connecting resistance R27～R36 one end respectively, the other end of resistance R 27～R36 is connecting resistance R17～R26 one end respectively, resistance R 17～R26 other end, resistance R 16 one end, capacitor C 22 one end, the negative pole of voltage-stabiliser tube D3 connects A point, A point connects the A point that electricity is adjusted attenuator circuit, resistance R 16 another termination capacitor C 23 one end, capacitor C 22, the anodal common ground of the C23 other end and voltage-stabiliser tube D3.
8.
light automatic gain control circuit for cable television network optical receiver according to claim 1, it is characterized in that described luminous power indicating circuit comprises capacitor C 24, C25, resistance R 37～R46, light-emitting diode D14～D23, the positive pole of light-emitting diode D14～D23 is connected with D/A change-over circuit with comparison circuit, the negative pole of light-emitting diode D14～D23 is connecting resistance R37～R46 one end respectively, another termination direct voltage+8V of resistance R 37～R46 and capacitor C 24,C25 one end, capacitor C 24, C25 other end ground connection.
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| CN201010617758.1A CN102130724B (en) | 2010-12-30 | 2010-12-30 | Light automatic gain control circuit used for cable TV network optical receiver |
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| CN101478344A (en) * | 2008-12-04 | 2009-07-08 | 上海大学 | Light control automatic gain control circuit applied on cable television network optical receiver |
| CN201947276U (en) * | 2010-12-30 | 2011-08-24 | 常熟市高事达光电科技有限公司 | Automatic optical gain control circuit for cable television network optical receiver |
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| JPS5850666Y2 (en) * | 1977-06-09 | 1983-11-18 | ホーチキ株式会社 | Remote control device for amplifier variable attenuation circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101478344A (en) * | 2008-12-04 | 2009-07-08 | 上海大学 | Light control automatic gain control circuit applied on cable television network optical receiver |
| CN201947276U (en) * | 2010-12-30 | 2011-08-24 | 常熟市高事达光电科技有限公司 | Automatic optical gain control circuit for cable television network optical receiver |
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| CN102130724A (en) | 2011-07-20 |
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Address after: 215532 Jiangsu city of Suzhou province Changshou City ancient town Baimao Industrial Zone Patentee after: Suzhou gaoshida information Polytron Technologies Inc Address before: The ancient town of Jiangsu province 215532 Changshou City Baimao Economic Development Zone Patentee before: Changshu Gaoshida Optoelectronic Technology Co., Ltd. |
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