Signal transmission system

Abstract

The utility model discloses a signal transmission system, and relates to the technical field of signal transmission. The signal transmission system comprises a signal generation branch, a resistor branch, a controller and a signal receiving branch. The signal generation branch is connected with the input voltage and is configured to generate an optical signal based on the input voltage, the signal generation branch comprises an electro-optical conversion unit, and the optical signal is output by the electro-optical conversion unit and is transmitted through an analog optical fiber. The resistance branch is respectively connected with the electro-optical conversion unit and the controller, the resistance branch is configured to be a resistor with an adjustable resistance value so as to adjust the current flowing through the electro-optical conversion unit, and the resistance value of the resistance branch is determined by the controller. The signal receiving branch is configured to receive an optical signal from the analog optical fiber and output a first voltage corresponding to the optical signal. In this way, the method can be suitable for transmission of different signals and is high in practicability.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of signal transmission, and in particular to a signal transmission system. Background Art

[0002] An optical fiber signal transmission system generally consists of three parts. These three parts include a transmitter that converts an electrical signal into an optical signal, an analog optical fiber that connects the transmitter and the receiver to transmit the optical signal, and a receiver that converts the optical signal into an electrical signal. The advantage of using an analog optical fiber to transmit signals is strong anti-interference performance and the ability to withstand very high voltages.

[0003] Currently, on the premise that the output voltage range of the optical fiber signal transmission system remains unchanged, the input voltage range also needs to remain unchanged, that is, the optical fiber signal transmission system can only be used for the transmission of a single signal (the voltage range corresponding to this signal is the input voltage range of the optical fiber signal transmission system), and it cannot be applied to the transmission of different signals, resulting in poor practicability. Summary of the Utility Model

[0004] The embodiments of the present application provide a signal transmission system that can be applied to the transmission of different signals and has strong practicability.

[0005] In a first aspect, the embodiments of the present application provide a signal transmission system, including:

[0006] A signal generation branch, connected to an input voltage, configured to generate an optical signal based on the input voltage. Among them, the signal generation branch includes an electro-optic conversion unit, and the optical signal is output by the electro-optic conversion unit and transmitted through an analog optical fiber;

[0007] A resistance branch and a controller, the resistance branch is respectively connected to the electro-optic conversion unit and the controller, and the resistance branch is configured as a resistor with an adjustable resistance value to adjust the current flowing through the electro-optic conversion unit, where the resistance value of the resistance branch is determined by the controller;

[0008] A signal reception branch, configured to receive the optical signal from the analog optical fiber and output a first voltage corresponding to the optical signal.

[0009] In one or more embodiments, the signal transmission system further includes:

[0010] A negative voltage source, respectively connected to the controller and the resistance branch, configured to output an adjustable first negative voltage. Among them, each time the resistance value of the resistance branch is adjusted, the first negative voltage is adjusted, and the adjustment multiples of the two are the same to keep the static operating current of the electro-optic conversion unit constant. The static operating current is the current flowing through the electro-optic conversion unit when the input voltage is 0.

[0011] In one or more embodiments, the negative voltage source has a current limiting function.

[0012] In one or more embodiments, the signal generation branch further includes a first amplifier and a switching transistor, and the signal transmission system further includes a positive voltage source;

[0013] The non-inverting input terminal of the first amplifier is connected to the input voltage, the inverting input terminal of the first amplifier is respectively connected to the second terminal of the switching transistor and the resistor branch, the output terminal of the first amplifier is connected to the first terminal of the switching transistor, the third terminal of the switching transistor is connected to the first terminal of the electro-optical conversion unit, and the second terminal of the electro-optical conversion unit is connected to the positive voltage source.

[0014] In one or more embodiments, the positive voltage source has a current limiting function.

[0015] In one or more embodiments, the signal generation branch further includes a second amplifier;

[0016] The non-inverting input terminal of the second amplifier is connected to the input voltage, the inverting input terminal of the second amplifier is respectively connected to the first terminal of the electro-optical conversion unit and the resistor branch, and the output terminal of the second amplifier is connected to the second terminal of the electro-optical conversion unit.

[0017] In one or more embodiments, the resistor branch includes a digitally controlled resistor;

[0018] The digitally controlled resistor is connected between the signal generation branch and the negative voltage source, and the digitally controlled resistor is connected to the controller, and the digitally controlled resistor adjusts its resistance value based on the control signal output by the controller.

[0019] In one or more embodiments, the resistor branch includes a single-pole multi-throw switch and N resistors, the single-pole multi-throw switch includes a single input contact and N output contacts, and the resistance values between any two of the N resistors are different, where N is an integer greater than 1;

[0020] The input contact is connected to the signal generation branch, each of the N output contacts is connected to the first terminal of one of the N resistors, the second terminals of the resistors in the N resistors are short-circuited and connected to the negative voltage source, and the single-pole multi-throw switch is connected to the controller.

[0021] In one or more embodiments, the electro-optical conversion unit includes a laser diode;

[0022] The cathode of the laser diode is the first terminal of the electro-optical conversion unit, and the anode of the laser diode is the second terminal of the electro-optical conversion unit.

[0023] In one or more embodiments, the signal receiving branch includes a photodiode and a third amplifier;

[0024] The cathode of the photodiode is connected to a positive voltage source, the anode of the photodiode is connected to the input terminal of the third amplifier, and the output terminal of the third amplifier outputs the first voltage.

[0025] The beneficial effects of the present application are as follows: The signal transmission system of the embodiments of the present application includes a signal generation branch, a resistance branch, a controller, and a signal receiving branch. The signal generation branch is connected to an input voltage and is configured to generate an optical signal based on the input voltage. Among them, the signal generation branch includes an electro-optic conversion unit. The optical signal is output by the electro-optic conversion unit and transmitted through an analog optical fiber. The resistance branch is respectively connected to the electro-optic conversion unit and the controller. The resistance branch is configured as a resistor with an adjustable resistance value to adjust the current flowing through the electro-optic conversion unit. Among them, the resistance value of the resistance branch is determined by the controller. The signal receiving branch is configured to receive the optical signal from the analog optical fiber and output a first voltage corresponding to the optical signal. Thus, when different signals (the ranges of the input voltages corresponding to different signals are different) are input, by only adjusting the resistance value of the resistance branch, the current flowing through the electro-optic conversion unit can be adjusted, and then the gain of the system can be adjusted, so that the first voltage can be kept constant. It can be seen that the signal transmission system can be applied to the transmission of different signals and has strong practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0027] Figure 1 is a schematic diagram of the block diagram of the signal transmission system provided by the embodiments of the present application Figure 1 ;

[0028] Figure 2 is a schematic diagram of the block diagram of the signal transmission system provided by the embodiments of the present application Figure 2 ;

[0029] Figure 3 is related to Figure 2 the schematic diagram of the circuit structure corresponding to the block diagram shown Figure 1 ;

[0030] Figure 4 is a schematic diagram of the first voltage and the current flowing through the laser diode provided by the embodiments of the present application;

[0031] Figure 5 is related to Figure 2Schematic diagram of the circuit structure corresponding to the shown composition block diagram Figure 2 ;

[0032] Figure 6 is related to Figure 2 Schematic diagram of the circuit structure corresponding to the shown composition block diagram Figure 3 . Specific implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and detailedly described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some but not all of the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0034] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween.

[0035] In addition, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0036] Please refer to Figure 1 , Figure 1 , which is a schematic diagram of the composition block diagram of the signal generation system provided by the embodiment of this application. As Figure 1 shown, the signal transmission system 100 includes a signal generation branch 10, a resistor branch 20, a controller 30, and a signal reception branch 40. Among them, the signal generation branch 10 includes an electro-optic conversion unit 11.

[0037] Among them, the signal generation branch 10 is connected to the input voltage VIN, and the resistor branch 20 is respectively connected to the electro-optic conversion unit 11 and the controller 30.

[0038] Specifically, the signal generation branch 10 is configured to generate an optical signal based on the input voltage VI N. Among them, the optical signal is output by the electro-optic conversion unit 11 and transmitted through the analog optical fiber 200. The resistor branch 20 is configured as a resistor with an adjustable resistance value to adjust the current flowing through the electro-optic conversion unit 11. Among them, the resistance value of the resistor branch 20 is determined by the controller 30. Specifically, the controller 30 outputs a control signal to the resistor branch 20. By adjusting the control signal output by the controller 30, the resistance value of the resistor branch 20 can be adjusted, and further the current flowing through the electro-optic conversion unit 11 can be adjusted. The signal reception branch 40 is configured to receive the optical signal from the analog optical fiber 200 and output a first voltage V1 corresponding to the optical signal.

[0039] Through the above process, when different signals are input, by simply adjusting the resistance value of the resistance branch 20 through the controller 30, the current flowing through the electro-optical conversion unit 11 can be adjusted, and then the gain of the signal transmission system 100 can be adjusted to keep the first voltage unchanged. Among them, the ranges of the input voltages corresponding to different signals are different. For example, in some embodiments, different signals include a signal with an input voltage range of [-1V, +1V] (denoted as the first signal) and a signal with an input voltage range of [-0.1V, +0.1V] (denoted as the second signal). The gain of the signal transmission system 100 refers to the ratio of the output signal to the input signal, which is expressed as a ratio of voltages (i.e., the ratio of the first voltage V1 to the input voltage VIN) in this embodiment, and this gain can be linear (proportional constant) or logarithmic (usually in decibels dB). In summary, when different signals are input, by simply adjusting the gain of the signal transmission system 100 in the above manner, the output signal (i.e., the first voltage V1) can be kept unchanged. For example, in some embodiments, if the range of the first voltage V1 is kept within [-1V, +1V], then when the first signal is input, the gain of the signal transmission system 100 is adjusted to 1; when the second signal is input, the gain of the signal transmission system 100 is adjusted to 10. It can be seen that the signal transmission system provided by the embodiments of the present application can be applied to the transmission of different signals and has strong practicability.

[0040] In one embodiment, as Figure 2 shown, the signal transmission system 100 further includes a negative voltage source V-.

[0041] Among them, the negative voltage source V- is respectively connected to the controller 30 and the resistance branch 20. The negative voltage source V- is configured to output an adjustable first negative voltage. Among them, each time the resistance value of the resistance branch 20 is adjusted, the first negative voltage is adjusted, and the adjustment multiples of the two are the same to keep the static operating current of the electro-optical conversion unit 11 constant. The static operating current is the current flowing through the electro-optical conversion unit 11 when the input voltage is 0.

[0042] For example, in some embodiments, if the range of the first voltage V1 is maintained at [-1V, +1V], when the first signal is input, the gain of the signal transmission system 100 is adjusted to 1, and it is assumed that the voltage output by the current negative voltage source V- is -0.3V; if the input is switched to the second signal, the gain of the signal transmission system 100 is adjusted to 10, then the voltage of the first negative voltage should be adjusted to 10 times simultaneously, that is, the voltage output by the negative voltage source V- is -3V at this time. Another example, in some embodiments, if the range of the first voltage V1 is maintained at [-0.1V, +0.1V], when the second signal is input, the gain of the signal transmission system 100 is adjusted to 1, and it is assumed that the voltage output by the current negative voltage source V- is -3V; if the input is switched to the first signal, the gain of the signal transmission system 100 is adjusted to 0.1, then the voltage of the first negative voltage should be adjusted to 1 / 10 simultaneously, that is, the voltage output by the negative voltage source V- is -0.3V at this time. Thus, the static operating current of the electro-optical conversion unit 11 can be kept constant to prevent the static operating current of the electro-optical conversion unit 11 from being too large and damaging the electro-optical conversion unit 11 when adjusting the gain of the signal transmission system 100.

[0043] In one embodiment, the negative voltage source has a current limiting function.

[0044] Specifically, since the input voltage VI N can have different ranges corresponding to different signals, there may be an abnormal situation where the gain of the signal transmission system 100 is forgotten to be switched when switching signals. For example, assuming that the range of the first voltage V1 is maintained at [-1V, +1V], and when switching from the second signal to the first signal, the gain of the signal transmission system 100 is forgotten to be switched, then at this time, the current flowing through the electro-optical conversion unit 11 will increase abnormally, and there is a risk of damaging the electro-optical conversion unit 11. Based on this, the embodiment of the present application further configures the negative voltage source V- to have a current limiting function to limit the current flowing through the electro-optical conversion unit 11 to be less than the maximum current allowed to flow through it, thereby protecting the electro-optical conversion unit 11 and extending its service life.

[0045] In some embodiments, the negative voltage source can be a negative linear voltage regulator of model LT3093 from Analog Devices, Inc. in the United States. Among them, LT3093 has a programmable current limiting function. By connecting a resistor between the I LI M and GND pins of LT3093, the current limiting point of LT3093 can be set, so that the maximum output current of LT3093 can be adjusted as needed to achieve the purpose of limiting the current flowing through the electro-optical conversion unit 11.

[0046] It is understandable that in other embodiments, a current-limiting circuit may also be provided on the path where the electro-optical conversion unit 11 is located to limit the current flowing through the electro-optical conversion unit 11 to be less than the maximum current it allows to flow through. The specific implementation process is within the scope easily understood by those skilled in the art and will not be elaborated here.

[0047] Please refer to Figure 3 , Figure 3 which exemplarily shows a circuit structure corresponding to the Figure 2 composition block diagram shown. As Figure 3 shown, the signal generation branch 10 further includes a first amplifier U1 and a switching transistor Q1, and the signal transmission system 100 further includes a positive voltage source V+.

[0048] Among them, the non-inverting input terminal of the first amplifier U1 is connected to the input voltage VIN, the inverting input terminal of the first amplifier U1 is respectively connected to the second terminal of the switching transistor Q1 and the resistor branch 20, the output terminal of the first amplifier U1 is connected to the first terminal of the switching transistor Q1, the third terminal of the switching transistor Q1 is connected to the first terminal of the electro-optical conversion unit 11, and the second terminal of the electro-optical conversion unit 11 is connected to the positive voltage source V+.

[0049] Specifically, the first amplifier U1 is used to amplify the input voltage VIN and input it to the switching transistor Q1 to turn on the switching transistor Q1 and generate a current, and this current flows through the resistor branch 20 and the electro-optical conversion unit 11.

[0050] Among them, in this embodiment, the switching transistor Q1 is taken as an NPN-type triode as an example. The base of the NPN-type triode is the first terminal of the switching transistor Q1, the emitter of the NPN-type triode is the second terminal of the switching transistor Q1, and the collector of the NPN-type triode is the third terminal of the switching transistor Q1.

[0051] The switching transistor Q1 can be any controllable switch, for example, an insulated gate bipolar transistor (IGBT) device, an integrated gate-commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field effect transistor (JFET) device, a MOS controlled thyristor (MCT) device, etc.

[0052] In this embodiment, the electro-optical conversion unit 11 includes a laser diode LD1.

[0053] Among them, the cathode of the laser diode LD1 is the first terminal of the electro-optical conversion unit 11, and the anode of the laser diode LD1 is the second terminal of the electro-optical conversion unit 11. That is, the cathode of the laser diode LD1 is connected to the third terminal of the switching transistor Q1, and the anode of the laser diode LD1 is connected to the positive voltage source V+.

[0054] Specifically, the laser diode LD1 is a semiconductor laser, also known as LD (Laser Diode). It uses semiconductor materials to generate and amplify laser beams. The working principle of the laser diode LD1 is to inject current into the semiconductor material, causing it to undergo stimulated emission and amplify into a laser (i.e., output an optical signal).

[0055] In this embodiment, the resistance branch 20 includes a digital control resistor 21.

[0056] Among them, the digital control resistor 21 is connected between the signal generation branch 10 and the negative voltage source V-, and the digital control resistor 21 is connected to the controller 30. Among them, a digital control resistor (Digital Potentiometer, Digi-Pot or Digital Pot) is a resistor that can be controlled through a digital interface. This type of resistor can be programmed to change its resistance value. In this embodiment, the digital control resistor 21 adjusts its resistance value based on the control signal output by the controller 30.

[0057] In this embodiment, the signal receiving branch 40 includes a photodiode PD1 and a third amplifier U3.

[0058] Among them, the cathode of the photodiode PD1 is connected to the positive voltage source V+, the anode of the photodiode PD1 is connected to the input terminal of the third amplifier U3, and the output terminal of the third amplifier U3 outputs a first voltage V1.

[0059] Specifically, the photodiode PD1 receives an optical signal from the analog optical fiber 200 and converts it into a second voltage. The second voltage is amplified by the third amplifier U3 to be the first voltage V1.

[0060] In the related art, on the premise that the output voltage range of the optical fiber signal transmission system remains unchanged, the range of its input voltage also needs to remain unchanged, that is, the optical fiber signal transmission system can only be used for the transmission of a single signal (the voltage range corresponding to this signal is the range of the input voltage of the optical fiber signal transmission system), and cannot be applied to the transmission of different signals.

[0061] And in the embodiment of the present application, as Figure 3In the illustrated embodiment, based on the virtual short and virtual open characteristics of the first amplifier U1, the voltages at the two input terminals of the first amplifier U1 will eventually be equal. Therefore, the input voltage VIN is equal to the voltage at the first end of the resistor branch 20 (i.e., the voltage at the first end of the digital control resistor 21). The voltage at the second end of the resistor branch 20 (i.e., the voltage at the second end of the digital control resistor 21) is the voltage provided by the negative voltage source V-. Then, the current ILD1 flowing through the laser diode LD1 = (VIN - V-) / r1 (denoted as Equation ①), where r1 is the resistance value of the resistor branch 20. From Equation ①, it can be obtained that 1 / r1 is the gain of the signal generation branch 10. Also, since the current ILD1 has a linear relationship with the optical signal, and the optical signal has a linear relationship with the first voltage V1, the gain of the entire signal transmission system 100 can be correspondingly adjusted by adjusting the gain of the signal generation branch 10. In summary, by adjusting r1, the gain of the signal transmission system 100 can be adjusted. Then, when different signals (with different ranges of input voltages corresponding to different signals) are input, by simply adjusting r1 to adjust the gain of the signal transmission system 100, the first voltage V1 can be kept constant. It can be seen that this signal transmission system is applicable to the transmission of different signals and has strong practicability.

[0062] In some embodiments, the gain can also be increased by adding an amplifier circuit before the signal generation branch or after the signal reception branch. However, on the one hand, this method requires setting different amplifier circuits for different signals, resulting in a complex circuit structure and high cost; on the other hand, it will cause an increase in system noise. For the embodiment of the present application, only r1 needs to be adjusted, with a simple circuit structure and low cost, and at the same time, it will not cause an increase in system noise.

[0063] Secondly, in the embodiment of the present application, while adjusting r1, the negative voltage source V- is also configured to be adjusted to keep the static operating current constant, which is beneficial to preventing the laser diode LD1 from being damaged due to excessive current.

[0064] Please refer to Figure 3 and Figure 4 , Figure 4 which exemplarily shows a way of the current flowing through the laser diode LD1 and the first voltage. As Figure 4As shown, the abscissa is the current \(I_{LD1}\) flowing through the laser diode LD1, and the ordinate is the first voltage \(V1\). Before the current \(I_{LD1}\) increases to equal the threshold current \(I_{th}\), the laser diode LD1 does not output an optical signal, and in this case, the first voltage \(V1\) remains at 0. After the current \(I_{LD1}\) increases to be greater than the threshold current \(I_{th}\), as the current \(I_{LD1}\) increases, the first voltage \(V1\) also increases. Moreover, the current \(I_{LD1}\) and the first voltage \(V1\) show a proportional relationship. For example, if the waveform of the current \(I_{LD1}\) is as shown by curve L1, then the waveform of the first voltage \(V1\) is as shown by curve L2. It can be seen that the waveforms of the current \(I_{LD1}\) and the first voltage \(V1\) show a proportional relationship, and this ratio is the electro-optical conversion coefficient of the laser diode LD1.

[0065] Meanwhile, in this embodiment, when the input voltage \(V_{IN}=0\), according to formula ①, we can obtain: the current \(I_{LD1}=-V_- / r1\). The current \(I_{LD1}\) at this time is denoted as the static operating current \(I_s\) of the laser diode LD1. By setting the static operating current \(I_s\) for the laser diode LD1, when the input voltage \(V_{IN}\) is input to this signal transmission system, the operating current of the laser diode LD1 can fluctuate up and down within the linear range near the static operating current \(I_s\), so that the first voltage \(V1\) also changes linearly accordingly. In this way, the first voltage \(V1\) will not produce signal distortion.

[0066] Taking the example that the current of the laser diode LD1 with a power of 5 milliwatts cannot exceed 30 mA, otherwise it will be permanently damaged. Meanwhile, assume that the range of the first voltage \(V1\) remains at \([-1V, +1V]\), and \(r1 = 200\Omega\). When the input voltage \(V_{IN}\) corresponds to the first signal (i.e., the range is \([-1V, +1V]\)), assume the negative voltage source \(V_-=-3V\). Then \(I_s=-V_- / r1 = 15 mA\). When the input voltage corresponds to the first signal, the current \(I_{LD1}\) of the laser diode LD1 is in the range of \([10 mA, 20 mA]\). It can be seen that the current \(I_{LD1}\) of the laser diode LD1 is less than 30 mA, and the laser diode LD1 will not be damaged.

[0067] However, when the input voltage \(V_{IN}\) is switched to correspond to the second signal, \(r1\) needs to be reduced by 10 times to 20 \(\Omega\). At this time, if the negative voltage source \(V_-\) is not processed correspondingly, then \(I_s=-V_- / r1 = 150 mA\), which far exceeds 30 mA and will cause the laser diode LD1 to be permanently damaged.

[0068] Based on this, while the embodiment of the present application realizes the adjustment of r1, it also configures the adjustment of the negative voltage source V-. Thus, when the input voltage VIN corresponds to the second signal after switching, r1 needs to be reduced by 10 times to 20Ω, and at the same time, the negative voltage source V- is also reduced by 10 times to -0.3V. At this time, Is = -V- / r1 = 15mA, and the static operating current remains unchanged, which is beneficial to preventing the laser diode LD1 from being damaged due to excessive current.

[0069] In addition, in the related art, a clamping circuit is usually set to clamp the input voltage VIN to a preset voltage value to prevent the current flowing through the laser diode LD1 from being too large due to the excessive input voltage VIN and damaging the laser diode LD1. However, if different signals need to be transmitted, corresponding clamping circuits need to be configured for each signal, the circuit structure is complex and the cost is also high; at the same time, it also requires a high level of user operation, and the user needs to keep the resistance value of the digital control resistor 21, the negative voltage source V- and the clamping circuit corresponding, otherwise it will also cause the current flowing through the laser diode LD1 to be too large and damage the laser diode LD1. For example, assume that after the input voltage VIN is switched from the second signal to the first signal, r1 is not adjusted in time (taking the above embodiment as an example, r1 is 20Ω), and the negative voltage source V- remains -0.3V. Then when the input voltage VIN is 1V, according to formula ①, the current ILD1 = (1 + 0.3) / 20 = 65mA > 30mA, which will also cause the current flowing through the laser diode LD1 to be too large and damage the laser diode LD1.

[0070] Based on this, an embodiment of the present application provides an implementation method of configuring the negative voltage source V- with a current limiting function, which not only does not require additional circuits to reduce costs, but also reduces the requirements for user operation. That is, even if the user operates incorrectly, for example, after the input voltage VIN is switched from the second signal to the first signal, r1 is not adjusted in time, it will not cause the current flowing through the laser diode LD1 to be too large. Thus, it can effectively protect the laser diode LD1.

[0071] In some embodiments, the embodiment of the present application also provides another method of configuring the positive voltage source V+ with a current limiting function. It can also prevent the laser diode LD1 from being damaged due to excessive current flowing through it. In short, at least one of the positive voltage source V+ and the negative voltage source V- is configured with a current limiting function, and it can prevent the laser diode LD1 from being damaged due to excessive current flowing through it.

[0072] It should be noted that as Figure 3The hardware structure of the signal transmission system 100 shown is only an example, and the signal transmission system 100 may have more or fewer components than shown in the figure, may combine two or more components, or may have a different component configuration. The various components shown in the figure may be implemented in hardware, software, or a combination of hardware and software including one or more signal processing and / or application-specific integrated circuits.

[0073] For example, Figure 5 Another implementation of the resistor branch 20 is shown as an example. Figure 5 As shown, the resistor branch includes a single-pole multi-throw switch 22 and N resistors. The single-pole multi-throw switch includes a single input contact SA1 and N output contacts, and the N output contacts include a first output contact S1, a second output contact S2, ..., and an Nth output contact SN. The input contact SA1 can be connected to one of the first output contact S1, the second output contact S2, ..., and the Nth output contact SN. The resistance values of any two resistors in the N resistors are different, and the N resistors include a first resistor RA1, a second resistor RA2, ..., and an Nth resistor RAN, where N is an integer greater than 1.

[0074] Among them, the input contact SA1 is connected to the signal generating branch 10. Each of the N output contacts is connected to the first end of one of the N resistors, that is, the first output contact S1 is connected to the first end of the first resistor RA1, the second output contact S2 is connected to the first end of the second resistor RA2, ..., the Nth output contact SN is connected to the first end of the Nth resistor RAN. The second end of each resistor in the N resistors is short-circuited and connected to the negative voltage source V-, that is, the second end of the first resistor RA1, the second end of the second resistor RA2, ..., the second end of the Nth resistor RAN is short-circuited and connected to the negative voltage source V-. The single-pole multi-throw switch 22 is connected to the controller 30.

[0075] Specifically, if the resistance values of any two resistors among the first resistor RA1, the second resistor RA2, ..., and the Nth resistor RAN are different, then when the input contact SA1 is connected to any output contact, the resistor connected to the output contact is connected to the circuit, and the resistance value of the resistor branch 20 is the resistance value of the resistor connected to the circuit. For example, if the controller 30 controls the input contact SA1 to be connected to the first output contact S1, the first resistor RA1 is connected to the circuit, and the resistance value of the resistor branch 20 is the resistance value of the first resistor RA1.

[0076] Another example: Figure 6 Another implementation of the signal generation branch 10 is shown as an example. Figure 6 As shown, the signal generating branch 10 further includes a second amplifier U1.

[0077] Among them, the non-inverting input terminal of the second amplifier U1 is connected to the input voltage VIN, the inverting input terminals of the second amplifier U2 are respectively connected to the first terminal of the electro-optical conversion unit 11 and the resistor branch 20, and the output terminal of the second amplifier U2 is connected to the second terminal of the electro-optical conversion unit 11.

[0078] Specifically, the second amplifier U1 is used to amplify the input voltage VIN and directly drive the photodiode LD1, so that the photodiode LD1 outputs an optical signal.

[0079] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

[0080] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A signal transmission system, characterized in that, Comprising: A signal generation branch, connected to an input voltage, configured to generate an optical signal based on the input voltage, wherein the signal generation branch includes an electro-optic conversion unit, the optical signal is output by the electro-optic conversion unit and transmitted through an analog optical fiber; A resistance branch and a controller, the resistance branch is respectively connected to the electro-optic conversion unit and the controller, the resistance branch is configured as a resistor with an adjustable resistance value to adjust the current flowing through the electro-optic conversion unit, wherein the resistance value of the resistance branch is determined by the controller; A signal reception branch, configured to receive the optical signal from the analog optical fiber and output a first voltage corresponding to the optical signal.

2. The signal transmission system according to claim 1, characterized in that, The signal transmission system further includes: A negative voltage source, respectively connected to the controller and the resistance branch, configured to output an adjustable first negative voltage, wherein each time the resistance value of the resistance branch is adjusted, the first negative voltage is adjusted, and the adjustment multiples of the two are the same to keep the static operating current of the electro-optic conversion unit constant, and the static operating current is the current flowing through the electro-optic conversion unit when the input voltage is 0.

3. The signal transmission system according to claim 2, wherein The negative voltage source has a current limiting function.

4. The signal transmission system according to claim 2, wherein The signal generation branch further includes a first amplifier and a switching tube, and the signal transmission system further includes a positive voltage source; The non-inverting input terminal of the first amplifier is connected to the input voltage, the inverting input terminal of the first amplifier is respectively connected to the second terminal of the switching tube and the resistance branch, the output terminal of the first amplifier is connected to the first terminal of the switching tube, the third terminal of the switching tube is connected to the first terminal of the electro-optic conversion unit, and the second terminal of the electro-optic conversion unit is connected to the positive voltage source.

5. The signal transmission system according to claim 4, characterized in that, The positive voltage source has a current limiting function.

6. The signal transmission system according to claim 2 or 3, characterized in that, The signal generation branch further includes a second amplifier; The non-inverting input terminal of the second amplifier is connected to the input voltage, the inverting input terminal of the second amplifier is respectively connected to the first terminal of the electro-optic conversion unit and the resistance branch, and the output terminal of the second amplifier is connected to the second terminal of the electro-optic conversion unit.

7. The signal transmission system according to claim 2, wherein The resistance branch includes a numerically controlled resistor; The numerically controlled resistor is connected between the signal generation branch and the negative voltage source, and the numerically controlled resistor is connected to the controller, and the numerically controlled resistor adjusts the resistance value based on the control signal output by the controller.

8. The signal transmission system according to claim 2, wherein The resistance branch includes a single-pole multi-throw switch and N resistors, the single-pole multi-throw switch includes a single input contact and N output contacts, and the resistance values between any two of the N resistors are different, where N is an integer greater than 1; The input contact is connected to the signal generation branch, each of the N output contacts is connected to the first end of one of the N resistors, the second ends of the N resistors are short-circuited and connected to the negative voltage source, and the single-pole multi-throw switch is connected to the controller.

9. The signal transmission system according to claim 1, wherein The electro-optic conversion unit includes a laser diode; The cathode of the laser diode is the first end of the electro-optic conversion unit, and the anode of the laser diode is the second end of the electro-optic conversion unit.

10. The signal transmission system according to claim 1, characterized in that, The signal receiving branch includes a photodiode and a third amplifier; The cathode of the photodiode is connected to a positive voltage source, the anode of the photodiode is connected to the input end of the third amplifier, and the output end of the third amplifier outputs the first voltage.

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