CN102377490A - Optical transmitter module predistortion circuit for cable television front-end optical communication platforms - Google Patents

Abstract

The invention relates to a predistortion circuit of an optical transmitting module used for a cable TV front-end optical communication platform, and belongs to the technical field of cable TV. Including amplifier module A1 , transistor V1 , V2 , diode D1 , radio frequency attenuation diode D2 , attenuator ATT , relay JD1 , branch coils Z1-Z3 , Z7 , distribution coil Z4 , coupling coil Z5 , Z6 , signal line R-75 , DC Overcurrent inductor L1 , air core inductor L2 , adjustable potentiometer W1-W3 , capacitors C1-C15 , C17-C21 , electrolytic capacitor C16 , resistors R1-R21 , among which A1 is the MC-7831 amplifier module of NEC Corporation of Japan. Advantages: A part of the signal is separated from the signal output by the amplifier module A1 to produce the second and third distortion signals, and then after "amplitude adjustment" and "frequency response flatness adjustment" , it becomes the second distortion produced by the laser , The three-time distortion signal with opposite phase is mixed into the signal output by the amplifying module A1 after delay processing, and then drives the laser to "neutralize and offset" the secondary and three-time distortion products generated by the laser, and improve the optical link. distortion index.

Description

Optical transmitter module pre-distortion circuit for cable TV front-end optical communication platform

technical field

The invention relates to an optical emission module predistortion circuit for an optical communication platform of a cable TV front end, belonging to the technical field of cable TV, in particular to a cable TV front end (or sub-front end) based on a two-way network transformation of a hybrid optical fiber coaxial cable network Optical transmission equipment in the computer room .

Background technique

Today, with the integration of the three networks and the rapid development of the network technology of the next-generation radio and television network (NGB), broadband, two-way, digital, and the transformation of the new generation of radio and television networks are advancing rapidly; Internet, enterprise private network, VOIP, digital TV and other value-added services Vigorous development; radio and television is moving towards the majority of carrier-class operators. Facing the market, customers and service is the only choice. According to the requirements of the State Administration of Radio, Film and Television, the HFC two-way network transformation is the transformation of the basic transmission network, including the basic realization of fiber-to-the-building and the gradual realization of fiber-to-the-home. With the continuous upgrading and transformation of HFC network, optical fiber network has rapidly replaced coaxial cable with low price, wider coverage, faster transmission speed and smaller failure rate. This trend requires a large number of optical transmission modules of the optical communication platform to be used in the front-end computer room of the cable TV operator, so that the optical transmission module of the optical communication platform in the front-end (or sub-front-end) computer room in the HFC network becomes a key device in the network . From the perspective of radio and television, the performance index of equipment is an important technical guarantee. Here I will develop an optical transmitter module pre-distortion circuit for a cable TV front-end optical communication platform according to the development of a new generation of broadcasting and television networks .

Contents of the invention

The object of the present invention is to provide a pre-distortion circuit for an optical transmitting module used in a cable television front-end optical communication platform that improves the optical link distortion index.

The purpose of the present invention is achieved in this way, a kind of optical transmission module predistortion circuit for cable television front-end optical communication platform, comprises amplifying module A1, triode V1, V2, diode D1, radio frequency attenuation diode D2, attenuator ATT, Relay JD1, branch coils Z1-Z3, Z7, distribution coil Z4, coupling coils Z5, Z6, signal line R-75, DC overcurrent inductor L1, air core inductor L2, adjustable potentiometer W1-W3, capacitor C1-C15, C17-C21, electrolytic capacitor C16, resistor R1-R21, among which A1 is the MC-7831 amplifier module of Japan NEC Company, one end of the cable TV RF signal input capacitor C1, the other end of the capacitor C1 is connected to one end of the resistor R1, and the other end of the resistor R1 The other end is connected to the main input end of the branch coil Z1, one end of the cable modulation and demodulation terminal system CMTS signal input capacitor C2, the other end of the capacitor C2 is connected to the branch input end of the branch coil Z1, and the main output end of the branch coil Z1 is connected to the attenuator ATT The input terminal of the branch coil Z1 is grounded, the branch output terminal of the branch coil Z1 is connected to one end of the resistor R2, the other end of the resistor R2 is grounded, the output terminal of the attenuator ATT is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to Pin 1 of the amplifier module A1, pins 2, 3, 7, and 8 of the amplifier module A1 are grounded, the voltage +5V is connected to capacitor C17, one end of resistor R11, and R14, the other end of capacitor C17 is grounded, and the other end of resistor R11 is connected to resistor R12 One end of the electrolytic capacitor C16, the positive electrode of the electrolytic capacitor C16, the negative electrode of the electrolytic capacitor C16 is grounded, the other end of the resistor R12 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the capacitor C18, the base of the transistor V1, and the other end of the capacitor C18 is grounded. The other end of the resistor R14 is connected to the collector of the transistor V1, the emitter of the transistor V1 is connected to one end of the resistor R15, the base of the transistor V2, the other end of the resistor R15, the emitter of the transistor V2 is grounded, the collector of the transistor V2 is connected to the positive electrode of the diode D1, and the relay Pin 4 of JD1, negative pole of diode D1, pins 1 and 3 of relay JD1 are connected to voltage +24V, pin 2 of relay JD1 is connected to capacitor C19, one end of DC overcurrent inductor L1, the other end of capacitor C19 is grounded, and DC overcurrent inductor L1 The other end is connected to pin 5 of the amplifier module A1, one end of the capacitor C20, the other end of the capacitor C20 is grounded, the pin 9 of the amplifier module A1 is connected to the main input end of the branch coil Z2, the center tap of the branch coil Z2 is grounded, and the branch output of the branch coil Z2 Connect one end of resistor R8 and R10, the other end of resistor R10 is grounded, the other end of resistor R8 is connected to resistor R9, one end of capacitor C4, the other end of resistor R9 is grounded, the other end of capacitor C4 is connected to input detection port -20dB, branch coil The branch input terminal of Z2 is connected to resistor R3 and one end of capacitor C13, the other end of resistor R3 and capacitor C13 is grounded, the main output terminal of branch coil Z2 is connected to the main output terminal of branch coil Z3, the center tap of branch coil Z3 is grounded, and the branch coil Z3 is branched output Connect one end of the resistor R4, the other end of the resistor R4 is grounded, the main input terminal of the branch coil Z3 is connected to one end of the capacitor C5, the other end of the capacitor C5 is connected to one end of the R-75 signal line, and the branch input terminal of the branch coil Z3 is connected to one end of the capacitor C6 , the other end of capacitor C6 is connected to pin 1 of distribution coil Z4, pin 2 of distribution coil Z4 is grounded, the center tap of the distribution coil is connected to one end of capacitor C14, the other end of capacitor C14 is grounded, pin 3 of distribution coil Z is connected to one end of resistor R7 1. Pin 1 of coupling coil Z5, pin 2 and pin 4 of coupling coil Z5 are grounded, pin 3 of coupling coil Z5 is connected to one end of capacitor C7, the other end of capacitor C7 is connected to pin 3 of adjustable potentiometer W1, and RF attenuation diode D2 2 pins, 1 pin of adjustable potentiometer W1 is grounded, 2 pins of adjustable potentiometer W1 are connected to one end of resistor R21, the other end of resistor R21, one end of capacitor C21 are connected to voltage +5V, and the other end of capacitor C21 is grounded. Pin 4 of the coil Z4 is connected to pin 1 of the coupling coil Z6 and the other end of the resistor R7, pins 2 and 4 of the coupling coil Z6 are grounded, pin 3 of the coupling coil Z6 is connected to one end of the capacitor C8, and the other end of the capacitor C8 is connected to an adjustable potential Pin 3 of the device W2, pin 3 of the radio frequency attenuation diode D2, pin 1 of the adjustable potentiometer W2 is grounded, pin 2 of the adjustable potentiometer W2 is connected to one end of the resistor R20, and the other end of the resistor R20 is connected to the voltage +5V, and the radio frequency attenuation Pin 1 of diode D2 is connected to capacitor C12 and one end of resistor R16, the other end of resistor R16 is grounded, the other end of capacitor C12 is connected to pin 1 of adjustable potentiometer W3, and pin 2 of adjustable potentiometer W3 is connected to one end of resistor R17. The other end of the resistor R17 is grounded, the 3-pin of the adjustable potentiometer W3 is connected to the resistor R19, the air-core inductor L2, and one end of the capacitor C9, the other end of the resistor R19 is connected to the other end of the air-core inductor L2, one end of the resistor R18, and the other end of the resistor R18 One end is grounded, the other end of the capacitor C9 is connected to the branch input end of the branch coil Z7, the center tap of the branch coil Z7 is grounded, the branch output terminal of the branch coil Z7 is connected to the resistor R5 and one end of the capacitor C15, the other end of the resistor R5 and the capacitor C15 is grounded, the branch coil The main output terminal of Z7 is connected to one end of the capacitor C11, the other end of the capacitor C11 is connected to the other end of the signal line R-75, the main input terminal of the branch coil Z7 is connected to one end of the capacitor C10, the other end of the capacitor C10 is connected to one end of the resistor R6, and the resistor R6 The other end of the output signal to the laser.

In the present invention, a part of the signal is separated from the signal output by the amplification module A1, and is used to manufacture secondary and tertiary distortion signals, and then after "amplitude adjustment" and "frequency response flatness adjustment", it becomes the secondary distortion produced by the laser , The three-time distortion signal with opposite phase is mixed into the signal output by the amplifying module A1 after delay processing, and then drives the laser to "neutralize and offset" the secondary and three-time distortion products generated by the laser, and improve the optical link. distortion index.

Description of drawings

Fig. 1 is a schematic diagram of the present invention.

Detailed ways

Refer to the figure: the present invention separates a part of the signal from the signal output by the amplifier module A1 after the RF signal of the cable TV is input, and then undergoes "amplitude adjustment" and "frequency response flatness adjustment" to make it a secondary signal generated by the laser The distorted and third-order distortion signals with opposite phases are mixed into the signal output by the amplifier module A1 after delay processing, and then drive the laser to "neutralize and cancel" the secondary and third distortion products produced by the laser to complete light emission Modular predistortion control. CATV radio frequency signal input capacitor C1, resistor R1, branch coil Z1 main input terminal, cable modulation and demodulation terminal system CMTS signal input capacitor C2, branch coil Z1 branch input terminal, branch coil Z1 center tap ground, branch coil Z1 branch output terminal Connect to the impedance matching resistor R2, mix the output signal through the branch coil Z1, pass the attenuator ATT, the capacitor C3, and input the pin 1 of the amplifier module A1, the electrolytic capacitor C16, the capacitor C17-C20, the resistor R11-R15, the transistor V1-V2, and the diode D1 , relay JD1, and DC overcurrent inductor L1 form a +24V power supply circuit to input the 5-pin of the amplifier module A1, the amplifier module A1 works, and after the signal is amplified, the 9-pin output of the amplifier module A1 passes through the main output terminal of the branch coil Z2, and the branch coil Z2 The center tap is grounded, the branch input terminal of the branch coil Z2 is connected to the impedance matching resistor R3 and the impedance matching capacitor C13, the branch output terminal of the branch coil Z2 passes through the resistor R8-R10 and the capacitor C4 to output the signal to the -20dB input detection port, and the main input terminal of the branch coil Z2 The output signal passes through branch coils Z3, Z7, distribution coil Z4, coupling coils Z5, Z6, capacitors C5-C12, C14-C15, C21, resistors R4, R5, R7, R16-R21, air-core inductor L2, adjustable potentiometer The output signal of the predistortion circuit composed of W1-W3 and R-75 signal lines is output to the laser through the impedance matching resistor R6. Among them, A1 is the MC-7831 amplifier module of Japan NEC Company, ATT is the British fixed attenuator, JD1 is the relay, V1, V2 are the triode, D1 is the diode, D2 is the radio frequency attenuation diode, L1 is the DC overcurrent inductor, L2 is the hollow Inductance, the R-75 signal line is a 75Ω impedance RF signal line, Z1-Z3, Z7 are branch coils, Z4 is a distribution coil, Z5, Z6 are coupling coils, W1-W3 are adjustable potentiometers, C1-C11 are high Frequency blocking direct capacitor, C12-C15 is impedance matching capacitor, C16 is electrolytic capacitor, C17-C21 is high frequency filter capacitor, R1-R6 is impedance matching resistor, R7 is isolation resistor, R8-R10 is attenuation resistor, R11-R14 , R20, R21 are current limiting resistors, and R15-R19 are voltage dividing resistors.

The most attractive benefit of the pre-distortion circuit of the optical transmission module is to separate a part of the signal from the output signal of the amplification module A1 to produce the second and third distortion signals, and then undergo "amplitude adjustment" and "frequency response flatness adjustment" , so that it becomes a signal opposite to the secondary distortion and tertiary distortion generated by the laser, which is mixed into the signal output by the amplifying module A1 after delay processing, and then drives the laser to "neutralize and offset" the laser. The secondary and tertiary distortion products improve the distortion index of the optical link .

Claims (1)

1. A kind of light emission module predistortion circuit that is used for Headend optical communication platform; It is characterized in that comprising amplification module A1; Triode V1; V2; Diode D1; Rf attenuation diode D2; Attenuator ATT; Relay J D1; The coil Z1-Z3 of branch; Z7; Distribute coil Z4; Coupling coil Z5; Z6; Holding wire R-75; Direct current overcurrent inductance L 1; Air core inductor L2; Adjustable potentiometer W1-W3; Capacitor C 1-C15; C17-C21; Electrochemical capacitor C16; Resistance R 1-R21; Wherein A1 is the MC-7831 amplification module of Japanese NEC Corporation; The end of cable TV radiofrequency signal input capacitance C1; The end of the other end connecting resistance R1 of capacitor C 1; The primary input end of another termination branch line circle Z1 of resistance R 1; The end of cable modem terminal system CMTS signal input capacitance C2; Branch's input of another termination branch line circle Z1 of capacitor C 2; The input of the main output termination attenuator ATT of the coil Z1 of branch; The centre cap ground connection of the coil Z1 of branch; The end of the output connecting resistance R2 of branch of the coil Z1 of branch; The other end ground connection of resistance R 2; One end of the output termination capacitor C 3 of attenuator ATT; 1 pin of another termination amplification module A1 of capacitor C 3; 2 of amplification module A1; 3; 7; 8 pin ground connection; Voltage+5V connects capacitor C 17; Resistance R 11; The end of R14; The other end ground connection of capacitor C 17; The end of the other end connecting resistance R12 of resistance R 11; The positive pole of electrochemical capacitor C16, electrochemical capacitor C16 minus earth, the end of the other end connecting resistance R13 of resistance R 12; One end of another termination capacitor C 18 of resistance R 13; The base stage of triode V1; The other end ground connection of capacitor C 18, the collector electrode of another termination triode V1 of resistance R 14, the end of triode V1 emitter connecting resistance R15; The base stage of triode V2; The other end of resistance R 15; It is anodal that triode V2 grounded emitter, triode V2 collector electrode meet diode D1; 4 pin of relay J D1, diode D1 negative pole; 1 of relay J D1; 3 pin meet voltage+24V; 2 pin of relay J D1 connect capacitor C 19; Direct current overcurrent inductance L 1 one ends; The other end ground connection of capacitor C 19,5 pin of another termination amplification module A1 of direct current overcurrent inductance L 1; One end of capacitor C 20, the other end ground connection of capacitor C 20; 9 pin of amplification module A1 connect the primary input end of the coil Z2 of branch; The coil Z2 of branch centre cap ground connection, the output connecting resistance R8 of branch of the coil Z2 of branch; The end of R10, resistance R 10 other end ground connection; The other end connecting resistance R9 of resistance R 8; One end of capacitor C 4; The other end ground connection of resistance R 9, another termination input of capacitor C 4 detects mouth-20dB, the input connecting resistance R3 of branch of the coil Z2 of branch; One end of capacitor C 13; Resistance R 3; The other end ground connection of capacitor C 13; The coil Z2 master of branch exports the main output of termination branch line circle Z3, the coil Z3 of branch centre cap ground connection, the end of the output connecting resistance R4 of coil Z3 branch of branch; The other end ground connection of resistance R 4; The end of the coil Z3 of branch primary input termination capacitor C5, an end of another termination R-75 holding wire of capacitor C 5, an end of coil Z3 branch of branch input termination capacitor C 6; 1 pin of another termination partition line circle Z4 of capacitor C 6; The 2 pin ground connection of distributing coil Z4, distribution coil centre cap connects an end of capacitor C 14, the other end ground connection of capacitor C 14; An end that distributes the 3 pin connecting resistance R7 of coil Z; 1 pin of coupling coil Z5; 2 of coupling coil Z5; 4 pin ground connection, 3 pin of coupling coil Z5 connect an end of capacitor C 7,3 pin of another termination adjustable potentiometer W1 of capacitor C 7; 2 pin of rf attenuation diode D2; The 1 pin ground connection of adjustable potentiometer W1; The end of the 2 pin connecting resistance R21 of adjustable potentiometer W1, the other end of resistance R 21; One termination voltage of capacitor C 21+5V, the other end ground connection of capacitor C 21; Distribute 4 pin of coil Z4 to connect 1 pin of coupling coil Z6 and the other end of resistance R 7; 2 of coupling coil Z6; 4 pin ground connection, 3 pin of coupling coil Z6 connect an end of capacitor C 8,3 pin of another termination adjustable potentiometer W2 of capacitor C 8; 3 pin of rf attenuation diode D2; The 1 pin ground connection of adjustable potentiometer W2; The end of the 2 pin connecting resistance R20 of adjustable potentiometer W2, another termination voltage+5V of resistance R 20,1 pin of rf attenuation diode D2 connects capacitor C 12; One end of resistance R 16; The other end ground connection of resistance R 16; 1 pin of another termination adjustable potentiometer W3 of capacitor C 12, the end of the 2 pin connecting resistance R17 of adjustable potentiometer W3, the other end ground connection of resistance R 17; The 3 pin connecting resistance R19 of adjustable potentiometer W3; Air core inductor L2; One end of capacitor C 9; The other end of another termination air core inductor L2 of resistance R 19; One end of resistance R 18, the other end ground connection of resistance R 18, another termination branch line circle Z7 branch input of capacitor C 9; The coil Z7 of branch centre cap ground connection; The output connecting resistance R5 of coil Z7 branch of branch; One end of capacitor C 15, resistance R 5; The other end ground connection of capacitor C 15, the coil Z7 master of branch exports an end of termination capacitor C 11; The other end of another terminated signal lines R-75 of capacitor C 11; The end of the coil Z7 of branch primary input termination capacitor C10, the end of the other end connecting resistance R6 of capacitor C 10, the other end output signal of resistance R 6 is to laser

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