Automatic gain adjusting circuit controlled by laser
By designing a laser-controlled automatic gain adjustment circuit, using photodetectors and operational amplifier components, and adjusting the bias voltage of electronic switches, the problem of unstable RF output signals of optical receivers is solved, and the problem of unstable optical receiver RF output signals is achieved when the optical power changes. The radio frequency output signal is stable, simple in structure and low in cost.
Patent Information
- Application Number
- CN202420983682.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-08
- Publication Date
- 2025-01-21
- Estimated Expiration
- 2034-05-08
AI Technical Summary
The radio frequency output signal of the existing optical receiver is greatly affected by the input optical power, resulting in unstable output signal when the optical power changes, and it is difficult for the prior art to realize automatic gain adjustment with a simple structure, low cost and easy to achieve.
Design a laser-controlled automatic gain adjustment circuit, using photodetectors composed of PIN photodiodes and operational amplifiers YF1 to YF10 and other components, and adjusting the bias voltage of electronic switches D11 and D12 to achieve stable output of radio frequency signals.
When the input optical power range is from -7dBm to +2dBm, by adjusting the bias voltage of the electronic switch to ensure that the radio frequency output signal is stable at the RF output port, the automatic gain adjustment function controlled by the laser is realized, and the structure is simple and low-cost Cheap and easy to implement.
Smart Images
Figure CN222381616U_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of optical fiber communication and broadcast television network, and in particular to an automatic gain adjustment circuit controlled by laser. Background Art
[0002] At present, the RF output signal of the optical receiver of the broadcasting and television network is affected by the input optical power. The higher the input optical power, the higher the output RF signal, and vice versa. Therefore, a laser-controlled automatic gain adjustment circuit is designed to make the output RF signal at the RF output port stable when the input optical power of the optical detector changes in the range of -7dBm to +2dBm. The circuit has a simple structure, low cost and is easy to implement. Summary of the invention
[0003] The purpose of the present invention is to solve the above problems. A laser-controlled automatic gain adjustment circuit is designed, which has a simple structure, low cost and is easy to implement. The circuit can output a stable RF signal within the input optical power range of -7dBm to +2dBm.
[0004] The technical solution adopted by the present invention to solve its technical problem is: a laser-controlled automatic gain adjustment circuit, characterized in that it consists of a light detector composed of a PIN photodiode, operational amplifiers YF1 to YF10, diodes D1 to D10, resistors R1 to R43, capacitors C1 to C12, inductor L1, inductor L2, transformer T1, radio frequency amplifier RF AMP, electronic switches D11 and D12 composed of PIN diodes, RF output port, and a DC power supply VCC.
[0005] The ports of the operational amplifiers YF1 to YF10 marked with a "-" sign are inverting input terminals, the ports marked with a "+" sign are non-inverting input terminals, and the ports without a sign are output terminals.
[0006] The function of the optical detector is to receive laser power and convert the received optical power into a radio frequency signal and a control voltage signal; the operational amplifiers YF1 to YF10, diodes D1 to D10, and resistors R1 to R31 constitute an electronic switch bias voltage control circuit; the electronic switches D11 and D12 composed of PIN diodes are electronic switches for radio frequency signals; the radio frequency amplifier RF AMP is a low-noise preamplifier for radio frequency signals; and the DC power supply VCC is used to power the circuit.
[0007] The positive electrode of the photodetector, one end of the capacitor C1 and one end of the inductor L1 are connected in parallel, and the other end of the capacitor C1 is grounded; the other end of the inductor L1 is connected in parallel with the resistor R32 and one end of the capacitor C2, and the other end of the capacitor C2 is grounded; the other end of the resistor R32 is connected in parallel with C3 and the reverse input ends of the operational amplifiers YF1, YF2, YF3, YF4, YF5, YF6, YF7, YF8, YF9 and YF10, and the other end of the capacitor C3 is grounded; the resistors R31, R21, R22, R23, R24, R25, R26, R27, R28, R29 and R30 are connected in series in sequence, the other end of the resistor R30 is grounded, and the other end of the resistor R31 is connected in parallel to the DC power supply VCC; the same-direction input end of the operational amplifier YF1 is connected in parallel with the resistors R31, R22, R23, R24, R25, R26, R27, R28, R29 and R30. 21; the same-direction input terminal of the operational amplifier YF2 is connected in parallel with the connection of the resistor R21 and the resistor R22; the same-direction input terminal of the operational amplifier YF3 is connected in parallel with the connection of the resistor R22 and the resistor R23; the same-direction input terminal of the operational amplifier YF4 is connected in parallel with the connection of the resistor R23 and the resistor R24; the same-direction input terminal of the operational amplifier YF5 is connected in parallel with the connection of the resistor R24 and the resistor R25; the same-direction input terminal of the operational amplifier YF6 is connected in parallel with the connection of the resistor R25 and the resistor R26; the same-direction input terminal of the operational amplifier YF7 is connected in parallel with the connection of the resistor R26 and the resistor R27; the same-direction input terminal of the operational amplifier YF8 is connected in parallel with the connection of the resistor R27 and the resistor R28; the same-direction input terminal of the operational amplifier YF9 is connected in parallel with the connection of the resistor R28 and the resistor R29; the same-direction input terminal of the operational amplifier YF10 is connected in parallel with the connection of the resistor R29 and the resistor R30.
[0008] The output end of the operational amplifier YF1 is connected in series with the positive electrode of the diode D1, the negative electrode of D1 is connected in series with one end of the resistor R1, and the other end of the resistor R1 is connected in series with one end of the resistor R11; the output ends of the operational amplifier YF2, operational amplifier YF3, operational amplifier YF4, operational amplifier YF5, operational amplifier YF6, operational amplifier YF7, operational amplifier YF8, operational amplifier YF9, and operational amplifier YF10 are connected in series with the positive electrodes of the diodes D2, D3, D4, D5, D6, D7, D8, D9, and D10 in sequence, the negative electrodes of the diodes D2, D3, D4, D5, D6, D7, D8, D9, and D10 are connected in series with one end of the resistors R2, R3, R4, R5, R6, R7, R8, R9, and R10 in sequence, and the resistors R2, R3, R4, R5, R6, R7, R8, R9, and R10 are connected in series with one end of the resistors R11, R12, R13, R14, R15, R16, R17, R18, R19, and R20. The other ends of R6, resistor R7, resistor R8, resistor R9 and resistor R10 are connected in series with one ends of resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, resistor R18, resistor R19 and resistor R20 respectively, and the connection method of the above devices is the same as the connection method of the output end of the operational amplifier YF1, the diode D1, the resistor R1 and the resistor R11; the other ends of the resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, resistor R18, resistor R19 and resistor R20 are connected in parallel with one end of the resistor R43, one end of the inductor L2, and one end of the capacitor C7 and capacitor C8, the other end of the resistor R43 is connected in parallel to the DC power supply VCC, and the other ends of the capacitor C7 and capacitor C8 are grounded.
[0009] The negative electrode of the photodetector is connected in series with the left tap of the transformer T1; the right tap of the transformer T1 is connected in series with one end of the resistor R33, the other end of the resistor R33 is connected in parallel with the resistor R34 and one end of the resistor R35, the other end of the resistor R35 is grounded, the other end of the resistor R34 is connected in parallel with the capacitor C5 and the DC power supply VCC, and the other end of the capacitor C5 is grounded; the middle tap of the transformer T1 is connected in series with one end of the capacitor C4, the other end of the capacitor C4 is connected in series with the input of the radio frequency amplifier RF AMP; the output of the radio frequency amplifier RF AMP is connected in series with one end of the capacitor C6; the other end of the capacitor C6 is connected in parallel with one end of the resistor R36 and the 3rd pin of the electronic switch D11, and the other end of R36 is grounded.
[0010] Pin 2 of the electronic switch D11 is connected in parallel with the other end of the inductor L2 and pin 2 of the electronic switch D12; pin 1 of the electronic switch D11 is connected in parallel with capacitor C10, resistor R39 and one end of resistor R40, and the other ends of capacitor C10 and resistor R39 are grounded; the other end of resistor R40 is connected in parallel with resistor R42 and one end of resistor R41; the other end of resistor R41 is connected in parallel with resistor R38, capacitor C9 and pin 1 of the electronic switch D12, and the other ends of capacitor C9 and resistor R38 are grounded; the other end of resistor R42 and one end of capacitor C12 are connected in parallel to a DC power supply VCC, and the other end of capacitor C12 is grounded.
[0011] Pin 3 of the electronic switch D12 is connected in parallel with the resistor R37 and one end of the capacitor C11, the other end of the resistor R37 is grounded, and the capacitor C11 is connected in series with the RF output port.
[0012] The beneficial effect of the present invention is that after the input optical signal is converted into a voltage signal at the positive electrode of the photodetector, the bias voltage of the electronic switches D11 and D12 is adjusted to adjust the insertion loss attenuation value of the electronic switch to the radio frequency signal, so that when the optical signal input to the photodetector changes in the optical power range of -7dBm to +2dBm, the radio frequency signal passing through the electronic switches D11 and D12 to the RF output port remains stable and unchanged, the structure is simple, the cost is low, and it is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a schematic diagram of the principle of one embodiment of the present invention. DETAILED DESCRIPTION
[0014] In order to make the purpose and technical solution of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and an embodiment. When the photodetector has a laser input, the photodetector converts the laser signal into a radio frequency signal and outputs it to the transformer T1 through the negative electrode of the photodetector, and then enters the radio frequency amplifier RF AMP through the middle tap of T1 and the capacitor C4. After being amplified by the RF AMP, the radio frequency signal enters the electronic switches D11 and D12 through C6, and then outputs to the RF output port through C11; at the same time, the positive electrode of the photodetector generates a control voltage affected by the input optical power, and the control voltage signal enters the operational amplifier YF1 to the reverse input terminal of the operational amplifier YF10 through the inductor L1 and the resistor R32; the stronger the laser signal input to the photodetector, the stronger the radio frequency signal converted through the negative electrode of the photodetector, and the higher the control voltage generated by the positive electrode of the photodetector, and vice versa.
[0015] exist Figure 1In the figure, since the bias voltage of the electronic switches D11 and D12 is negatively correlated with the positive voltage of the photodetector and the bias voltage of the electronic switches D11 and D12 is positively correlated with the insertion loss attenuation value of the RF signal passing through them, when the bias voltage provided to the electronic switches D11 and D12 by L2 reaches its rated conduction value, the electronic switches D11 and D12 are turned on, and the RF signal passing through the electronic switches passes without attenuation; when the bias voltage provided to the electronic switches D11 and D12 by L2 is lower than the rated conduction value, the RF signal passing through the electronic switches also attenuates linearly as the bias voltage decreases.
[0016] When -7dBm optical power is input to the detector, op amp YF10 outputs a low level, and the other op amps output a high level. The bias voltage through inductor L2 to electronic switches D11 and D12 is about 4.2V, and electronic switches D11 and D12 are turned on. The RF signal coming through C6 passes through electronic switches D11 and D12 without attenuation and is then output through C11 and the RF output port. When -6dBm optical power is input to the detector, op amps YF9 and YF10 output a low level, and the other op amps output a high level. The voltage through inductor L2 to electronic switches D11 and D12 is about 3.4V, which is linear with the electronic switches D11 and D12 when -7dBm optical power is input. Attenuation, the RF signal passing through C6 is linearly attenuated by the electronic switch and then output through C11 and the RF output port; when the input optical power is -5dBm, -4dBm, -3dBm, -2dBm, -1dBm, 0dBm, +1dBm, +2dBm, the bias voltage value from the inductor L2 to the electronic switches D11 and D12 is reduced linearly as described above, and the RF signal passing through the electronic switch is also linearly attenuated and then passes through C11 and the RF output port, so that when the input optical power of the optical detector changes in the range of -7dBm to +2dBm, its output RF signal at the RF output port is stable and unchanged, thereby realizing the function of automatic gain adjustment controlled by laser.
[0017] The above technical solutions only reflect the preferred technical solutions of the present invention. Any changes that may be made to certain parts thereof by those skilled in the art all reflect the principles of the present invention and fall within the protection scope of the present invention.
Claims
1. A laser-controlled automatic gain adjustment circuit, characterized in that: It consists of a light detector composed of a PIN photodiode, operational amplifiers YF1 to YF10, diodes D1 to D10, resistors R1 to R43, capacitors C1 to C12, inductor L1, inductor L2, transformer T1, radio frequency amplifier RF AMP, electronic switches D11 and D12 composed of PIN diodes, RF output port, and DC power supply VCC.
2. The laser-controlled automatic gain adjustment circuit according to claim 1, characterized in that: The function of the optical detector is to receive laser power and convert the received optical power into a radio frequency signal and a control voltage signal; the operational amplifiers YF1 to YF10, diodes D1 to D10, and resistors R1 to R31 constitute an electronic switch bias voltage control circuit; the electronic switches D11 and D12 composed of PIN diodes are electronic switches for radio frequency signals; the radio frequency amplifier RF AMP is a low-noise preamplifier for radio frequency signals; and the DC power supply VCC is used to power the circuit.
3. The laser-controlled automatic gain adjustment circuit according to claim 1, characterized in that: The positive electrode of the photodetector, one end of the capacitor C1 and one end of the inductor L1 are connected in parallel, and the other end of the capacitor C1 is grounded; the other end of the inductor L1 is connected in parallel with the resistor R32 and one end of the capacitor C2, and the other end of the capacitor C2 is grounded; the other end of the resistor R32 is connected in parallel with C3 and the reverse input ends of the operational amplifiers YF1, YF2, YF3, YF4, YF5, YF6, YF7, YF8, YF9 and YF10, and the other end of the capacitor C3 is grounded; the resistors R31, R21, R22, R23, R24, R25, R26, R27, R28, R29 and R30 are connected in series in sequence, the other end of the resistor R30 is grounded, and the other end of the resistor R31 is connected in parallel to the DC power supply VCC; the same-direction input end of the operational amplifier YF1 is connected in parallel with the resistors R31, R22, R23, R24, R25, R26, R27, R28, R29 and R30. 21; the same-direction input terminal of the operational amplifier YF2 is connected in parallel with the connection of the resistor R21 and the resistor R22; the same-direction input terminal of the operational amplifier YF3 is connected in parallel with the connection of the resistor R22 and the resistor R23; the same-direction input terminal of the operational amplifier YF4 is connected in parallel with the connection of the resistor R23 and the resistor R24; the same-direction input terminal of the operational amplifier YF5 is connected in parallel with the connection of the resistor R24 and the resistor R25; the same-direction input terminal of the operational amplifier YF6 is connected in parallel with the connection of the resistor R25 and the resistor R26; the same-direction input terminal of the operational amplifier YF7 is connected in parallel with the connection of the resistor R26 and the resistor R27; the same-direction input terminal of the operational amplifier YF8 is connected in parallel with the connection of the resistor R27 and the resistor R28; the same-direction input terminal of the operational amplifier YF9 is connected in parallel with the connection of the resistor R28 and the resistor R29; the same-direction input terminal of the operational amplifier YF10 is connected in parallel with the connection of the resistor R29 and the resistor R30.
4. The laser-controlled automatic gain adjustment circuit according to claim 1, characterized in that: The output end of the operational amplifier YF1 is connected in series with the positive electrode of the diode D1, the negative electrode of D1 is connected in series with one end of the resistor R1, and the other end of the resistor R1 is connected in series with one end of the resistor R11; the output ends of the operational amplifier YF2, operational amplifier YF3, operational amplifier YF4, operational amplifier YF5, operational amplifier YF6, operational amplifier YF7, operational amplifier YF8, operational amplifier YF9, and operational amplifier YF10 are connected in series with the positive electrodes of the diodes D2, D3, D4, D5, D6, D7, D8, D9, and D10 in sequence, the negative electrodes of the diodes D2, D3, D4, D5, D6, D7, D8, D9, and D10 are connected in series with one end of the resistors R2, R3, R4, R5, R6, R7, R8, R9, and R10 in sequence, and the resistors R2, R3, R4, R5, R6, R7, R8, R9, and R10 are connected in series with one end of the resistors R11, R12, R13, R14, R15, R16, R17, R18, R19, and R20. The other ends of R6, resistor R7, resistor R8, resistor R9 and resistor R10 are connected in series with one ends of resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, resistor R18, resistor R19 and resistor R20 respectively, and the connection method of the above devices is the same as the connection method of the output end of the operational amplifier YF1, the diode D1, the resistor R1 and the resistor R11; the other ends of the resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, resistor R18, resistor R19 and resistor R20 are connected in parallel with one end of the resistor R43, one end of the inductor L2, and one end of the capacitor C7 and capacitor C8, the other end of the resistor R43 is connected in parallel to the DC power supply VCC, and the other ends of the capacitor C7 and capacitor C8 are grounded.
5. The laser-controlled automatic gain adjustment circuit according to claim 1, characterized in that: The negative electrode of the photodetector is connected in series with the left tap of the transformer T1; the right tap of the transformer T1 is connected in series with one end of the resistor R33, the other end of the resistor R33 is connected in parallel with the resistor R34 and one end of the resistor R35, the other end of the resistor R35 is grounded, the other end of the resistor R34 is connected in parallel with the capacitor C5 and the DC power supply VCC, and the other end of the capacitor C5 is grounded; the middle tap of the transformer T1 is connected in series with one end of the capacitor C4, the other end of the capacitor C4 is connected in series with the input of the radio frequency amplifier RF AMP; the output of the radio frequency amplifier RF AMP is connected in series with one end of the capacitor C6; the other end of the capacitor C6 is connected in parallel with one end of the resistor R36 and the 3rd pin of the electronic switch D11, and the other end of R36 is grounded.
6. The laser-controlled automatic gain adjustment circuit according to claim 1, characterized in that: Pin 2 of the electronic switch D11 is connected in parallel with the other end of the inductor L2 and pin 2 of the electronic switch D12; pin 1 of the electronic switch D11 is connected in parallel with capacitor C10, resistor R39 and one end of resistor R40, and the other ends of capacitor C10 and resistor R39 are grounded; the other end of resistor R40 is connected in parallel with resistor R42 and one end of resistor R41; the other end of resistor R41 is connected in parallel with resistor R38, capacitor C9 and pin 1 of the electronic switch D12, and the other ends of capacitor C9 and resistor R38 are grounded; the other end of resistor R42 and one end of capacitor C12 are connected in parallel to a DC power supply VCC, and the other end of capacitor C12 is grounded.
7. The laser-controlled automatic gain adjustment circuit according to claim 1, characterized in that: Pin 3 of the electronic switch D12 is connected in parallel with the resistor R37 and one end of the capacitor C11, the other end of the resistor R37 is grounded, and the capacitor C11 is connected in series with the RF output port.