Signal receiving device and signal transmission system

Abstract

The present application discloses a signal receiving device and a signal transmission system. The signal receiving device includes a photoelectric conversion module and a current generating module. The photoelectric conversion module generates a first current based on an optical signal. The current generating module generates a second current. The signal receiving device also includes a signal conversion module and a signal attenuation module. The signal conversion module outputs a first voltage that is linearly related to the first current difference, and the first current difference is the difference between the first current and the second current. The signal attenuation module is controlled by a control voltage and outputs a second voltage whose signal strength is less than or equal to the first voltage. Alternatively, the signal receiving device also includes a signal processing module, which inputs the first current, the second current and the control voltage, and outputs a fourth voltage that is proportional to the first current difference, and the ratio between the fourth voltage and the first current difference is controlled by the control voltage. In the above manner, the bandwidth can be increased and the noise can be reduced.

Description

Technical Field

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

[0002] At present, the optical fiber signal transmission system usually consists of three parts. These three parts include the transmitting part that converts the electrical signal into the optical signal, the analog optical fiber that connects the transmitting part and the receiving part and is used to transmit the optical signal, and the receiving part that converts the optical signal into the electrical signal. The advantage of using analog optical fiber to transmit signals is that it has strong anti-interference performance and can withstand very high voltages.

[0003] However, the receiving part of the current optical fiber signal transmission system has a small bandwidth and large noise. Utility Model Content

[0004] The embodiments of the present application provide a signal receiving device and a signal transmission system, which can increase bandwidth and reduce noise.

[0005] In a first aspect, an embodiment of the present application provides a signal receiving device for receiving an optical signal from an analog optical fiber, the signal receiving device comprising:

[0006] A photoelectric conversion module, configured to generate a first current based on the optical signal;

[0007] A current generating module configured to generate a second current;

[0008] The signal receiving device also includes one of the following two solutions:

[0009] (i) The signal receiving device further comprises:

[0010] a signal conversion module, connected to the photoelectric conversion module and the current generation module respectively, inputting the first current and the second current, and configured to output a first voltage which is linearly related to the first current difference, wherein the first current difference is the difference between the first current and the second current;

[0011] a signal attenuation module, connected to the signal conversion module, inputting the first voltage and a control voltage, and configured to be controlled by the control voltage and output a second voltage with a signal strength less than or equal to the first voltage;

[0012] (ii) the signal receiving device further comprises:

[0013] The signal processing module is respectively connected to the photoelectric conversion module and the current generating module, and inputs the first current, the second current and the control voltage, and is configured to output a fourth voltage that is proportional to the first current difference, and the ratio between the fourth voltage and the first current difference is controlled by the control voltage.

[0014] In one or more embodiments, the current generating module includes a first resistor;

[0015] The first resistor is connected between a reference voltage and the signal conversion module, wherein a ratio of the reference voltage to the first resistor is the second current.

[0016] In one or more embodiments, the current generating module further includes a voltage follower connected between the reference voltage and the first resistor, or the current generating module further includes a buffer connected between the reference voltage and the first resistor.

[0017] In one or more embodiments, the signal conversion module includes a first operational amplifier and a second resistor;

[0018] The non-inverting input terminal of the first operational amplifier is grounded, the inverting input terminal of the first operational amplifier is respectively connected to the photoelectric conversion module and the current generation module, the output terminal of the first operational amplifier is connected to the signal attenuation module, and the second resistor is connected between the inverting input terminal and the output terminal of the first operational amplifier.

[0019] In one or more embodiments, the signal attenuation module includes a third resistor and a first junction field effect transistor;

[0020] The third resistor is connected between the signal conversion module and the drain of the first junction field effect transistor, the gate of the first junction field effect transistor inputs the control voltage, the source of the first junction field effect transistor is grounded, and the drain of the first junction field effect transistor outputs the second voltage.

[0021] In one or more embodiments, the signal attenuation module includes a fourth resistor and a second junction field effect transistor;

[0022] The fourth resistor is connected between the source of the second junction field effect transistor and ground, the gate of the second junction field effect transistor inputs the control voltage, the drain of the second junction field effect transistor is connected to the signal conversion module, wherein the source of the second junction field effect transistor outputs the second voltage.

[0023] In one or more embodiments, the signal attenuation module includes a fifth resistor, a sixth resistor and a radio frequency attenuator;

[0024] The fifth resistor is connected between the signal conversion module and the input end of the RF attenuator, the sixth resistor is connected between the output end of the RF attenuator and the ground, the control end of the RF attenuator inputs the control voltage, and the output end of the RF attenuator outputs the second voltage.

[0025] In one or more embodiments, the photoelectric conversion module includes a photodiode;

[0026] The anode of the photodiode is connected to a negative power supply, and the cathode of the photodiode is connected to the signal conversion module and the current generation module respectively.

[0027] In one or more embodiments, the signal receiving device further includes:

[0028] The signal amplification module is connected to the signal attenuation module, receives the second voltage as input, and is configured to amplify the second voltage and output a third voltage.

[0029] In one or more embodiments, the signal processing module includes a second operational amplifier and a third junction field effect transistor;

[0030] The non-inverting input terminal of the second operational amplifier is grounded, the inverting input terminal of the second operational amplifier is respectively connected to the photoelectric conversion module, the current generation module and the source of the third junction field effect transistor, the output terminal of the second operational amplifier is connected to the drain of the third junction field effect transistor and outputs the fourth voltage, and the gate of the third junction field effect transistor inputs the control voltage.

[0031] In a second aspect, an embodiment of the present application provides a signal transmission system, including a signal sending device, a simulated optical fiber, and a signal receiving device as described above;

[0032] The signal sending device is used to output an optical signal and transmit it through the analog optical fiber;

[0033] The signal receiving device is used to receive the optical signal from the analog optical fiber.

[0034] The beneficial effects of the present application are as follows: the signal receiving device of the embodiment of the present application is used to receive an optical signal from an analog optical fiber, and the signal receiving device includes a photoelectric conversion module and a current generating module. The photoelectric conversion module is configured to generate a first current based on the optical signal. The current generating module is configured to generate a second current. Scheme (i) is: the signal receiving device also includes a signal conversion module and a signal attenuation module. Among them, the signal conversion module is respectively connected to the photoelectric conversion module and the current generating module, the signal conversion module inputs the first current and the second current, and the signal conversion module is configured to output a first voltage that is linearly related to the first current difference, wherein the first current difference is the difference between the first current and the second current. The signal attenuation module is connected to the signal conversion module, the signal attenuation module inputs the first voltage and the control voltage, and the signal attenuation module is configured to be controlled by the control voltage and output a second voltage whose signal strength is less than or equal to the first voltage. Solution (ii) is: the signal receiving device further includes a signal processing module, the signal processing module is connected to the photoelectric conversion module and the current generating module respectively, the signal processing module inputs the first current, the second current and the control voltage, the signal processing module is configured to output a fourth voltage that is proportional to the first current difference, and the ratio between the fourth voltage and the first current difference is controlled by the control voltage. In the above manner, both solution (i) and solution (ii) can achieve the purpose of increasing bandwidth and reducing noise while converting the optical signal into an electrical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] One or more embodiments are exemplarily described by the figures in the accompanying drawings, which are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0036] Figure 1 This is a schematic diagram of the structure of the signal transmission system provided in the embodiment of the present application. Figure 1 ;

[0037] Figure 2 This is a schematic diagram of the structure of the signal transmission system provided in the embodiment of the present application. Figure 2 ;

[0038] Figure 3 is a schematic diagram of a transmitted signal and a static optical power provided in an embodiment of the present application;

[0039] Figure 4 This is a schematic diagram of the structure of the signal receiving device provided in the embodiment of the present application. Figure 1 ;

[0040] Figure 5 is with Figure 4 The circuit structure corresponding to the structure shown is shown in FIG. Figure 1 ;

[0041] Figure 6 is with Figure 4 The circuit structure corresponding to the structure shown is shown in FIG. Figure 2 ;

[0042] Figure 7 is with Figure 4 The circuit structure corresponding to the structure shown is shown in FIG. Figure 3 ;

[0043] Figure 8 is with Figure 4 The circuit structure corresponding to the structure shown is shown in FIG. Figure 4 ;

[0044] Fig. 9 This is a schematic diagram of the structure of the signal receiving device provided in the embodiment of the present application. Figure 2 ;

[0045] Fig.10 This is a schematic diagram of the structure of the signal receiving device provided in the embodiment of the present application. Figure 3 ;

[0046] Fig.11 is with Fig.10 Schematic diagram of circuit structure corresponding to the structure shown. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and in detail in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] It should be noted that, when an element is described as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may exist therebetween.

[0049] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0050] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the signal transmission system provided in the embodiment of the present application. Figure 1 As shown, the signal transmission system 1000 includes a signal receiving device 100, a signal sending device 200 and a simulated optical fiber 300 in any embodiment of the present application.

[0051] The signal sending device 200 is used to output an optical signal and transmit it through the analog optical fiber 300. An optical signal is a form of information transmission, which uses light waves to carry information. Figure 2 As shown, the signal sending device 200 includes a voltage-to-current conversion module A1 and a laser diode LD1. Among them, the first end of the laser diode LD1 is connected to the positive power supply V+, the second end of the laser diode LD1 is connected to the second end of the voltage-to-current conversion module A1, and the first end of the voltage-to-current conversion module A1 is connected to the input voltage VI N. Specifically, the voltage-to-current conversion module A1 can realize the linear conversion of the input voltage VIN into a current flowing through the laser diode LD1, thereby realizing a voltage-controlled current source. The laser diode LD1 is a semiconductor laser, also known as LD (Laser Di ode). 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 to generate stimulated radiation and amplify it into a laser (i.e., output light signal).

[0052] In some specific embodiments, the voltage-current conversion module A1 includes an amplifier, a power transistor and a resistor. The first input end of the amplifier is connected to the switch module, the second input end of the first amplifier is respectively connected to the first end of the resistor and the emitter of the power transistor, the collector of the power transistor is connected to the laser diode LD1, the output end of the amplifier is connected to the base of the power transistor, and the second end of the resistor is connected to the negative power supply. For example, the first input end of the amplifier is the in-phase input end, and the second input end is the inverting input end. Specifically, the amplifier is used to amplify its input voltage VI N and input it to the power transistor to turn on the power transistor and generate a current flowing through the laser diode LD1.

[0053] The signal receiving device 100 is used to receive an optical signal from the analog optical fiber 300, and output a corresponding output voltage based on the optical signal. In order to make the output voltage present a linear relationship with the input voltage V IN (wherein, a linear relationship exists between two variables, such as a proportional relationship), so as to ensure that the signal transmission system 1000 maintains a high transmission accuracy during the signal transmission process, at least the following two conditions need to be met:

[0054] The first condition is that, since light intensity is not negative, the laser diode LD1 that converts the electrical signal into an optical signal actually superimposes the electrical signal on a static optical power, such as Figure 3As shown, curve L1 is the signal to be transmitted, and curve L2 is the static optical power. When the input voltage VIN is 0, the current flowing through the laser diode LD1 is the static working current, and the power on the laser diode LD1 is the static optical power. Since the static optical power will be transmitted to the signal receiving device 100, the static optical power needs to be eliminated in the signal receiving device 100.

[0055] In the related art, a subtraction circuit is usually used to eliminate static optical power, and the subtraction circuit is implemented by a differential amplifier. For example, a differential amplifier of the THS3217 model of Ti company is used. However, in the process of implementing this application, the applicant found that the subtraction circuit in the related art has the problem of small bandwidth and large noise. Even though the THS3217 model differential amplifier is already the differential amplifier with the largest bandwidth, its bandwidth is only about 800MHz, and cannot reach more than 1GHz, which is obviously far from meeting the current bandwidth requirements for signal receiving devices. Moreover, in actual application scenarios, in actual application scenarios, the differential amplifier is an active device, which usually has a large noise, and precisely because it is an active device, its bandwidth is difficult to continue to increase.

[0056] Based on this, the signal receiving device 100 in the embodiment of the present application no longer uses a subtraction circuit, but cleverly uses the process of converting optical signals into electrical signals to eliminate static optical power (both solutions (i) and (ii) can be implemented) to ensure a larger bandwidth while reducing noise. The specific implementation process will be described later.

[0057] The second condition is that in the process of realizing the transmission of analog signals by optical fiber, the electro-optical conversion coefficient of the laser diode LD1 will have temperature drift, and this temperature drift will also affect the signal receiving device. Therefore, it is necessary to set a corresponding circuit to fine-tune the voltage of the electrical signal obtained from the optical signal to compensate for the temperature drift, thereby reducing or eliminating the temperature drift.

[0058] In the related art, a variable gain amplifier (VGA) is usually used to fine-tune the voltage of the electrical signal obtained from the optical signal. For example, the VCA824 adjustable gain amplifier of Ti Company. However, in the process of implementing this application, the applicant found that the adjustable gain amplifier in the related art also has the problem of small bandwidth and large noise. Even though the VCA824 adjustable gain amplifier is already the differential amplifier with the largest bandwidth, its bandwidth is only about 800MHz, and it cannot reach more than 1GHz, and it is far from meeting the current bandwidth requirements for signal receiving devices. Moreover, in actual application scenarios, the adjustable gain amplifier is an active device, which usually has a large noise, and precisely because it is an active device, its bandwidth is difficult to continue to increase.

[0059] Based on this, the signal receiving device 100 in the embodiment of the present application no longer uses an adjustable gain amplifier, but after cleverly using the process of converting optical signals into electrical signals to eliminate the static optical power, a passive signal attenuation module is used (Solution (i)), or the process of directly and cleverly using optical signals into electrical signals not only eliminates the static optical power, but also adjusts the signal gain at the same time (Solution (ii)). Therefore, both Scheme (i) and Scheme (ii) can ensure a larger bandwidth while reducing noise. The specific implementation process will be described later.

[0060] Please refer to Figure 4 , Figure 4 A schematic diagram of the structure of a signal receiving device provided in an embodiment of the present application, Figure 4 The schematic diagram of the structure of scheme (i) is shown. Figure 4 As shown, the signal receiving device 100 is used to receive an optical signal from a simulated optical fiber 300. The signal receiving device 100 includes a photoelectric conversion module 10, a current generation module 20, a signal conversion module 30 and a signal attenuation module 40.

[0061] The signal conversion module 30 is connected to the photoelectric conversion module 10 and the current generation module 20 respectively, and the signal attenuation module 40 is connected to the signal conversion module 30. Specifically, the first ends of the photoelectric conversion module 10, the current generation module 20 and the signal conversion module 30 are connected to the first node N1, and the second end of the signal conversion module 30 is connected to the signal attenuation module 40.

[0062] Specifically, the photoelectric conversion module 10 is configured to generate a first current I1 based on the optical signal, and the first current I1 flows out from the first node N1. The first current I1 corresponds to the optical signal. In some embodiments, the first current I1 corresponds to the optical signal in that the optical signal and the first current I1 have a proportional relationship, such as a positive proportional relationship.

[0063] The current generating module 20 is configured to generate a second current I 2 which flows into the first node N 1 .

[0064] The signal conversion module 30 inputs the first current I1 and the second current I2, and is configured to output a first voltage V1 which is linearly related to the first current difference, wherein the first current difference is the difference between the first current I1 and the second current I2.

[0065] The signal attenuation module 40 is a passive module. The signal attenuation module 40 inputs a first voltage V1 and a control voltage VC. The signal attenuation module 40 is configured to be controlled by the control voltage VC and output a second voltage V2 whose signal strength is less than or equal to the first voltage V1. Specifically, the signal attenuation module 40 has an attenuation ratio, and the magnitude of the attenuation ratio is determined by the control voltage VC. For example, the attenuation ratio can be set to increase with the increase of the control voltage VC, or the attenuation ratio can be set to decrease with the increase of the control voltage VC. The larger the attenuation ratio, the more the signal attenuation of the first voltage V1, that is, the greater the difference in signal strength between the first voltage V1 and the second voltage V2; conversely, the smaller the attenuation ratio, the less the signal attenuation of the first voltage V1, that is, the smaller the difference in signal strength between the first voltage V1 and the second voltage V2, and when the attenuation ratio is 0, the signal strengths of the first voltage V1 and the second voltage V2 are equal (that is, the first voltage V1 is equal to the second voltage V2). The control voltage VC can be provided by a circuit inside or outside the signal receiving device 100, for example, by a switching power supply outside the signal receiving device 100.

[0066] In this embodiment, the second current I2 can be configured to be equal to the current generated by the static optical power on the photoelectric conversion module 10, so that the second current I2 can be used to cleverly eliminate the current generated by the static optical power on the photoelectric conversion module 10 in the process of converting the optical signal into a voltage, so as to eliminate the influence of the static optical power on the laser diode LD1. In this process, there is no need to use a subtraction circuit including a differential amplifier as in the related art, which is beneficial to the application to increase bandwidth and reduce noise. In addition, the signal conversion module 30 can also be implemented in a passive manner to ensure that a larger bandwidth and smaller noise can be achieved.

[0067] Secondly, in different application scenarios, the second current I2 can change with the change of the current generated by the static optical power on the photoelectric conversion module 10, so as to be suitable for different application scenarios and have strong practicality.

[0068] Furthermore, this embodiment also uses a passive signal attenuation module to ensure a larger bandwidth while reducing noise, thereby increasing the overall bandwidth of the signal receiving device 100 and reducing the overall noise of the signal receiving device 100.

[0069] In one embodiment, if Figure 5 As shown, the photoelectric conversion module 10 includes a photodiode PD1.

[0070] The anode of the photodiode PD1 is connected to the negative power supply V-, and the cathode of the photodiode PD1 is connected to the signal conversion module 30 and the current generation module 20 at the first node N1 respectively.

[0071] Specifically, the photodiode PD1 is used to receive an optical signal from the analog optical fiber 300 and generate a first current I1 based on the optical signal. The working principle of the photodiode PD1 is based on the photoelectric effect, that is, when light irradiates a specific semiconductor material (ie, the photodiode PD1), current can be generated.

[0072] In this embodiment, the current generating module 20 includes a first resistor R1 .

[0073] The first resistor R1 is connected between the reference voltage VREF and the signal conversion module 30 , and the ratio of the reference voltage VREF to the first resistor R1 is the second current I 2 .

[0074] Specifically, the reference voltage VREF is a preset voltage, which can be set based on actual application scenarios. In some embodiments, the reference voltage VREF can be determined by configuring the second current I2 to be equal to the current generated by the static optical power on the photoelectric conversion module 10, and then based on VREF=I2*R1.

[0075] In this embodiment, the signal conversion module 30 includes a first operational amplifier A2 and a second resistor R2.

[0076] Among them, the non-inverting input terminal of the first operational amplifier A2 is grounded GND, the inverting input terminal of the first operational amplifier A2 is respectively connected to the photoelectric conversion module 10 and the current generation module 20 at the first node N1, the output terminal of the first operational amplifier A2 is connected to the signal attenuation module 40, and the second resistor R2 is connected between the inverting input terminal and the output terminal of the first operational amplifier A2.

[0077] Specifically, the relationship between the first voltage V1 and the first current difference (I 1-I 2) is: V1 = (I 1-I 2)*R2. It can be seen that the first voltage V1 and the first current difference (I 1-I 2) present a linear relationship.

[0078] In this embodiment, the signal attenuation module 40 includes a third resistor R3 and a first junction field effect transistor M1 .

[0079] The third resistor R3 is connected between the signal conversion module 30 and the drain of the first junction field effect transistor M1. The gate of the first junction field effect transistor M1 inputs the control voltage VC. The source of the first junction field effect transistor M1 is grounded GND. The drain of the first junction field effect transistor M1 outputs the second voltage V2.

[0080] Specifically, when the control voltage VC is 0, the first junction field effect transistor M1 is in the cut-off region, the first junction field effect transistor M1 can be regarded as a high resistance resistor, the voltage division of the first voltage V1 on the first junction field effect transistor M1 is much greater than the voltage division of the first voltage V1 on the third resistor R3, which can be regarded as an attenuation ratio of 0, and the first voltage V1 is equal to the second voltage V2. When the control voltage VC is less than 0, the first junction field effect transistor M1 is in the linear region, and the first junction field effect transistor M1 is used as a variable resistor. In addition, as the control voltage VC decreases, the equivalent resistance value of the first junction field effect transistor M1 also decreases, the voltage division of the first voltage V1 on the first junction field effect transistor M1 also decreases, the corresponding attenuation ratio increases, the signal strength attenuation of the first voltage V1 increases, and the signal strength of the second voltage V2 decreases.

[0081] exist Figure 5 In the embodiment shown, by using a high-speed operational amplifier as the first operational amplifier A2, the overall bandwidth of the electro-optical conversion module 10, the current generation module 20 and the signal conversion module 30 can be made larger, much larger than 1 GHz. In addition, since there is no need to add a subtraction circuit as in the related art, the cost can also be reduced.

[0082] Secondly, the third resistor R3 and the first junction field effect transistor M1 are both passive devices, which can achieve a bandwidth of more than 10 GHz, which is much larger than the bandwidth of about 800 MHz that can only be achieved by using an adjustable gain amplifier in the related art. In addition, in actual operation, there is no noise in the third resistor R3 and the first junction field effect transistor M1.

[0083] It can be understood that for the signal attenuation module 40 composed of the third resistor R3 and the first junction field effect transistor M1, its linear range is relatively small, that is, the signal input to the signal attenuation module 40 cannot be too large, otherwise it will cause signal distortion. Therefore, it is necessary to ensure that the signal input to the signal attenuation module 40 is relatively small so that the signal attenuation module 40 can be used, but at the same time, the demand for a larger bandwidth must be met. It is based on this that the embodiment of the present application creatively eliminates the static optical power in the process of converting the optical signal into an electrical signal to meet the above two requirements at the same time. Specifically, on the one hand, it can meet the requirement that the signal input to the signal attenuation module 40 is relatively small so that the signal attenuation module 40 can be used; on the other hand, there is no need to use a subtraction circuit, so that a larger bandwidth can be obtained by using a high-speed first operational amplifier A2.

[0084] It should be noted that if Figure 5The hardware structure of the signal receiving device 100 shown is only an example, and the signal receiving device 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.

[0085] For example, in one embodiment, Figure 6 As shown, the current generating module 20 further includes a voltage follower A3 or a buffer A4. The following embodiments take the current generating module 20 including the voltage follower A3 as an example.

[0086] Among them, the voltage follower A3 (or buffer A4) is connected between the reference voltage VREF and the first resistor R1. Voltage follower (Vo l tage Fo ll ower) is a circuit design whose output voltage is consistent with the input voltage, but can provide a greater current output capability. In the circuit, the voltage follower is usually implemented using an operational amplifier and is suitable for application scenarios that require high input impedance and low output impedance. Buffer (Buffer) is a circuit or device used to enhance the driving capability of the signal and reduce interference during signal transmission. Its output voltage is consistent with the input voltage. The buffer usually has high input impedance and low output impedance to maintain signal stability and prevent signal distortion or attenuation.

[0087] Another example: Figure 7 Another circuit structure of the signal attenuation module 40 is exemplarily shown. Figure 7 As shown, the signal attenuation module 40 includes a fourth resistor R4 and a second junction field effect transistor M2 .

[0088] The fourth resistor R4 is connected between the source of the second junction field effect transistor M2 and the ground GND, the gate of the second junction field effect transistor M2 inputs the control voltage VC, the drain of the second junction field effect transistor M2 is connected to the signal conversion module 40, and the source of the second junction field effect transistor M2 outputs the second voltage V2.

[0089] Specifically, when the control voltage VC is 0, the second junction field effect transistor M2 is in the cut-off region, the first junction field effect transistor M1 can be regarded as a high-resistance resistor, and the voltage division of the first voltage V1 on the fourth resistor R4 is much smaller than the voltage division of the first voltage V1 on the second junction field effect transistor M2, which can be regarded as the maximum attenuation ratio, and the signal strength of the second voltage V2 is the weakest. When the control voltage VC is less than 0, the second junction field effect transistor M2 is in the linear region, and the second junction field effect transistor M2 is used as a variable resistor. Moreover, as the control voltage VC decreases, the equivalent resistance value of the second junction field effect transistor M2 also decreases, the voltage division of the first voltage V1 on the second junction field effect transistor M2 also decreases, the corresponding attenuation ratio decreases, the signal strength attenuation of the first voltage V1 decreases, and the signal strength of the second voltage V2 increases.

[0090] In this embodiment, similarly, the fourth resistor R4 and the second junction field effect transistor M2 are both passive devices, which can achieve a bandwidth of more than 10 GHz, which is much larger than the bandwidth of about 800 MHz that can only be achieved by using an adjustable gain amplifier in the related art. In addition, in actual operation, there is no noise in the fourth resistor R4 and the second junction field effect transistor M2.

[0091] It can be understood that for the signal attenuation module 40 composed of the fourth resistor R4 and the second junction field effect transistor M2, its linear range is relatively small, that is, the signal input to the signal attenuation module 40 cannot be too large, otherwise it will cause signal distortion. Therefore, it is necessary to ensure that the signal input to the signal attenuation module 40 is relatively small so that the signal attenuation module 40 can be used, but at the same time, the demand for a larger bandwidth must be met. It is based on this that the embodiment of the present application creatively eliminates the static optical power in the process of converting the optical signal into an electrical signal to meet the above two requirements at the same time. Specifically, on the one hand, it can meet the requirement that the signal input to the signal attenuation module 40 is relatively small so that the signal attenuation module 40 can be used; on the other hand, there is no need to use a subtraction circuit, so that a larger bandwidth can be obtained by using a high-speed first operational amplifier A2.

[0092] For example, Figure 8 Another circuit structure of the signal attenuation module 40 is exemplarily shown. Figure 8 As shown, the signal attenuation module 40 includes a fifth resistor R5, a sixth resistor R6 and a radio frequency attenuator A4.

[0093] Among them, the fifth resistor R5 is connected between the signal conversion module 30 and the input end of the RF attenuator A4, the sixth resistor R6 is connected between the output end of the RF attenuator A4 and the ground GND, the control end of the RF attenuator A4 inputs the control voltage VC, and the output end of the RF attenuator A4 outputs the second voltage V2.

[0094] Specifically, the fifth resistor R5 and the sixth resistor R6 are matching resistors matched with the RF attenuator A4. By adjusting the control voltage VC, the attenuation ratio of the RF attenuator A4 can be adjusted, wherein the attenuation ratio varies from 0DB to several tens of DB. An RF attenuator is a device or component used to reduce the amplitude of an RF signal. The RF attenuator can provide a variable attenuation amount, which is usually expressed in decibels (DB).

[0095] In one embodiment, if Fig. 9 As shown, the signal receiving device 100 further includes a signal amplifying module 50 .

[0096] The signal amplification module 50 inputs the second voltage V2 and is configured to amplify the second voltage V2 and output a third voltage V3.

[0097] In some specific embodiments, the signal amplification module 50 includes an amplifier for amplifying the second voltage V2 and outputting a third voltage V3, wherein the input end of the amplifier is connected to the signal attenuation module 40, and the output end of the amplifier outputs the third voltage V3.

[0098] Please refer to Fig.10 , Fig.10 This is a schematic diagram of the structure of a signal receiving device provided in another embodiment of the present application. Fig.10 The schematic diagram of the structure of scheme (ii) is shown. Fig.10 As shown, the signal receiving device 100 is used to receive an optical signal from a simulated optical fiber 300. The signal receiving device 100 includes a photoelectric conversion module 10, a current generation module 20 and a signal processing module 60.

[0099] The photoelectric conversion module 10 and the current generation module 20 are the same as those in the above embodiment and will not be described in detail here.

[0100] The signal processing module 60 is respectively connected to the photoelectric conversion module 10 and the current generation module 20. The first end of the photoelectric conversion module 10, the current generation module 20 and the signal processing module 60 is connected to the second node N1, and the second end of the signal processing module 60 outputs the fourth voltage V4.

[0101] Specifically, the signal processing module 60 inputs the first current I1, the second current I2 and the control voltage VC, and the first current I1 flows out from the second node N2. The signal processing module 60 is configured to output a fourth voltage V4 that is proportional to the first current difference (here, a positive proportional relationship), and the ratio between the fourth voltage V4 and the first current difference (recorded as K1, also called gain) is controlled by the control voltage VC, and K1 is greater than 0, that is, V4 / (I1-I2)=K1, where K1>0. The larger the K1, the larger the corresponding gain, and the greater the signal strength of the fourth voltage V4; the smaller the K1, the smaller the corresponding gain, and the smaller the signal strength of the fourth voltage V4. The size of K1 is controlled by the control voltage VC. For example, K1 can be set to increase as the control voltage VC increases, or K1 can be set to decrease as the control voltage VC increases.

[0102] In this embodiment, the second current I2 can be configured to be equal to the current generated by the static optical power on the photoelectric conversion module 10, so that the second current I2 can be used to cleverly eliminate the current generated by the static optical power on the photoelectric conversion module 10 in the process of converting the optical signal into a voltage, so as to eliminate the influence of the static optical power on the laser diode LD1. In this process, there is no need to use a subtraction circuit including a differential amplifier as in the related art, which is conducive to the implementation of the present application to increase bandwidth and reduce noise. In addition, the signal processing module 60 can also be implemented in a passive manner to ensure that a larger bandwidth and smaller noise can be achieved.

[0103] Secondly, in the process of converting the optical signal into voltage, the embodiment cleverly uses the proportional coefficient (i.e., K1) to adjust the signal strength, without using an adjustable gain amplifier as in the related art, which is beneficial for the embodiment of the present application to reduce noise while ensuring a large bandwidth. Thus, the overall bandwidth of the signal receiving device 100 is increased, and the overall noise of the signal receiving device 100 is reduced.

[0104] Furthermore, in different application scenarios, the second current I2 can change with the change of the current generated by the static optical power on the photoelectric conversion module 10, so as to be suitable for different application scenarios and have strong practicality.

[0105] Please refer to Fig.11 , Fig.11 An example is shown with Fig.10 A circuit structure corresponding to the structure shown in FIG. 1 . The circuit structure of the current generating module 20 and the photoelectric conversion module 10 is similar to Figure 5-Figure 8 The circuit structure shown is the same as that shown in Figure 5-Figure 8 The description will not be repeated here.

[0106] In this embodiment, if Fig.11 As shown, the signal processing module 60 includes a second operational amplifier A6 and a third junction field effect transistor M3.

[0107] Among them, the non-inverting input terminal of the second operational amplifier A6 is grounded GND, the inverting input terminal of the second operational amplifier A6 is respectively connected to the photoelectric conversion module 10, the current generation module 20 and the source of the third junction field effect transistor M3, the output terminal of the second operational amplifier A6 is connected to the drain of the third junction field effect transistor M3, and outputs the fourth voltage V4, and the gate input control voltage VC of the third junction field effect transistor M3.

[0108] Specifically, the fourth voltage V4 and the first current difference (I 1-I 2) satisfy the relationship: V4=(I 1-I 2)*K1. It can be seen that the fourth voltage V4 and the first current difference (I 1-I 2) are in direct proportion.

[0109] Wherein, K1 is the equivalent resistance of the third junction field effect transistor M3, and is controlled by the control voltage VC. When the control voltage VC is 0, the third junction field effect transistor M3 is in the cut-off region, and the third junction field effect transistor M3 can be regarded as a high-resistance resistor, corresponding to the maximum gain, and the fourth voltage V4 obtained at this time is the maximum. When the control voltage VC is less than 0, the third junction field effect transistor M3 is in the linear region, and the third junction field effect transistor M3 is used as a variable resistor. Moreover, as the control voltage VC decreases, the equivalent resistance value of the third junction field effect transistor M3 also decreases, the gain (i.e., K1) also decreases, and the signal strength of the fourth voltage V4 also decreases.

[0110] exist Fig.11 In the embodiment shown, by using a high-speed operational amplifier as the second operational amplifier A6, the overall bandwidth of the electro-optical conversion module 10, the current generating module 20 and the signal processing module 60 can be made larger, much larger than 1 GHz. In addition, since there is no need to add a subtraction circuit and an adjustable gain amplifier as in the related art, the cost can also be reduced.

[0111] Secondly, the third junction field effect transistor M3 is a passive device, which can achieve a bandwidth of more than 10 GHz, which is much larger than the bandwidth of about 800 MHz that can only be achieved by using an adjustable gain amplifier in the related art. In addition, in actual operation, the third junction field effect transistor M3 does not have any noise.

[0112] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0113] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit 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. It should be understood by ordinary technicians in this field that they can still modify the technical solutions recorded in the above embodiments, or replace some of the technical features by equivalents; 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 receiving device, characterized in that: Used to receive an optical signal from an analog optical fiber, the signal receiving device comprises: A photoelectric conversion module, configured to generate a first current based on the optical signal; A current generating module configured to generate a second current; The signal receiving device also includes one of the following two solutions: (i) The signal receiving device further comprises: a signal conversion module, connected to the photoelectric conversion module and the current generation module respectively, inputting the first current and the second current, and configured to output a first voltage which is linearly related to the first current difference, wherein the first current difference is the difference between the first current and the second current; a signal attenuation module, connected to the signal conversion module, inputting the first voltage and a control voltage, and configured to be controlled by the control voltage and output a second voltage with a signal strength less than or equal to the first voltage; (ii) the signal receiving device further comprises: The signal processing module is respectively connected to the photoelectric conversion module and the current generating module, and inputs the first current, the second current and the control voltage, and is configured to output a fourth voltage that is proportional to the first current difference, and the ratio between the fourth voltage and the first current difference is controlled by the control voltage.

2. The signal receiving device according to claim 1, characterized in that: The current generating module comprises a first resistor; The first resistor is connected between a reference voltage and the signal conversion module, wherein a ratio of the reference voltage to the first resistor is the second current.

3. The signal receiving device according to claim 2, characterized in that: The current generating module further includes a voltage follower connected between the reference voltage and the first resistor, or the current generating module further includes a buffer connected between the reference voltage and the first resistor.

4. The signal receiving device according to claim 1, characterized in that: The signal conversion module includes a first operational amplifier and a second resistor; The non-inverting input terminal of the first operational amplifier is grounded, the inverting input terminal of the first operational amplifier is respectively connected to the photoelectric conversion module and the current generation module, the output terminal of the first operational amplifier is connected to the signal attenuation module, and the second resistor is connected between the inverting input terminal and the output terminal of the first operational amplifier.

5. The signal receiving device according to claim 1, characterized in that: The signal attenuation module includes a third resistor and a first junction field effect transistor; The third resistor is connected between the signal conversion module and the drain of the first junction field effect transistor, the gate of the first junction field effect transistor inputs the control voltage, the source of the first junction field effect transistor is grounded, and the drain of the first junction field effect transistor outputs the second voltage.

6. The signal receiving device according to claim 1, characterized in that: The signal attenuation module includes a fourth resistor and a second junction field effect transistor; The fourth resistor is connected between the source of the second junction field effect transistor and ground, the gate of the second junction field effect transistor inputs the control voltage, the drain of the second junction field effect transistor is connected to the signal conversion module, wherein the source of the second junction field effect transistor outputs the second voltage.

7. The signal receiving device according to claim 1, characterized in that: The signal attenuation module includes a fifth resistor, a sixth resistor and a radio frequency attenuator; The fifth resistor is connected between the signal conversion module and the input end of the RF attenuator, the sixth resistor is connected between the output end of the RF attenuator and the ground, the control end of the RF attenuator inputs the control voltage, and the output end of the RF attenuator outputs the second voltage.

8. The signal receiving device according to claim 1, characterized in that: The photoelectric conversion module includes a photodiode; The anode of the photodiode is connected to a negative power supply, and the cathode of the photodiode is connected to the signal conversion module and the current generation module respectively.

9. The signal receiving device according to claim 1, characterized in that: Also includes: The signal amplification module is connected to the signal attenuation module, receives the second voltage as input, and is configured to amplify the second voltage and output a third voltage.

10. The signal receiving device according to claim 1, characterized in that: The signal processing module includes a second operational amplifier and a third junction field effect transistor; The non-inverting input terminal of the second operational amplifier is grounded, the inverting input terminal of the second operational amplifier is respectively connected to the photoelectric conversion module, the current generation module and the source of the third junction field effect transistor, the output terminal of the second operational amplifier is connected to the drain of the third junction field effect transistor and outputs the fourth voltage, and the gate of the third junction field effect transistor inputs the control voltage.

11. A signal transmission system, characterized in that: It comprises a signal sending device, a simulated optical fiber and a signal receiving device as claimed in any one of claims 1 to 10; The signal sending device is used to output an optical signal and transmit it through the analog optical fiber; The signal receiving device is used to receive the optical signal from the analog optical fiber.

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