Analog signal transmission circuit and vehicle-mounted electronic equipment

Abstract

The utility model discloses an analog signal transmission circuit and vehicle-mounted electronic equipment. The analog signal transmission circuit comprises a conversion module, a current mirror and a dynamic voltage regulation module, the conversion module is used for converting the voltage signal into a first current signal and outputting the first current signal from the second end of the conversion module. The current mirror is used for generating a second current signal according to the first current signal and providing the second current signal to the load, and the second current signal is equal to the first current signal. And the dynamic voltage regulating module is used for controlling the voltage applied to the current mirror to keep constant by regulating the impedance of the dynamic voltage regulating module. The voltage signal is converted into the current signal for transmission, so that the influence caused by ground noise can be avoided, and the circuit is relatively simple and relatively low in cost. Meanwhile, the dynamic voltage regulating module can bear the voltage of the changing part of the load when the voltage at the two ends of the load changes, and a symmetrical working environment is provided for the current mirror, so that the symmetry of the current mirror is ensured.

Description

Technical Field

[0001] This application belongs to the technical field of signal transmission, and particularly relates to an analog signal transmission circuit and a vehicle-mounted electronic device. Background Art

[0002] Currently, due to cost advantages, cameras and displays using analog video signals are widely used in the field of vehicle-mounted monitoring.

[0003] However, during the transmission of analog video signals between devices, there is a relatively significant problem, that is, when transmitting analog video signals between devices, ground noise will be superimposed on the analog video signals and thus received by the receiving device, forming interference.

[0004] Currently, the transmission circuits used to transmit analog video signals are mainly voltage-driven circuits. For the above-mentioned ground noise problem, voltage-driven circuits are difficult to avoid the interference of ground noise and can only eliminate the influence of ground noise through relatively complex or costly solutions. Summary of the Utility Model

[0005] The purpose of this application is to provide an analog signal transmission circuit and a vehicle-mounted electronic device, aiming to solve the problem of ground noise existing in traditional analog video signal transmission.

[0006] The first aspect of the embodiment of this application provides an analog signal transmission circuit, including:

[0007] A conversion module, the first end of the conversion module is used to access a voltage signal, and the conversion module is used to convert the voltage signal into a first current signal and output it from the second end of the conversion module;

[0008] A current mirror, the first end of the current mirror is connected to the second end of the conversion module, the second end of the current mirror is used to connect to a load, and the current mirror is used to generate and provide a second current signal to the load according to the first current signal, and the second current signal is equal to the first current signal;

[0009] A dynamic voltage regulation module, the dynamic voltage regulation module is connected between the second end of the current mirror and the load, and the dynamic voltage regulation module is also connected to the first end of the current mirror. The dynamic voltage regulation module is used to control the voltage applied to the current mirror to remain constant by adjusting its own impedance.

[0010] In one embodiment, the dynamic voltage regulation module includes a third switching device, the first end of the third switching device is connected to the second end of the current mirror, the second end of the third switching device is used to connect to the load, and the control end of the third switching device is connected to the first end of the current mirror.

[0011] In one embodiment, the third switching device is a PNP bipolar junction transistor (BJT). The first end of the third switching device is the emitter of the PNP BJT, the second end of the third switching device is the collector of the PNP BJT, and the control end of the third switching device is the base of the PNP BJT.

[0012] In one embodiment, the current mirror includes a unidirectional conductor, a first switching device, and a second switching device.

[0013] The first end of the first switching device is for connecting to a driving voltage. The second end of the first switching device is connected to the anode of the unidirectional conductor. The cathode of the unidirectional conductor is connected to the second end of the conversion module. The control end of the first switching device is connected to the control end of the second switching device. The first end of the second switching device is connected to the first end of the first switching device. The second end of the second switching device is respectively connected to the dynamic voltage regulation module and the control end of the second switching device.

[0014] In one embodiment, the unidirectional conductor is a diode, and both the first switching device and the second switching device are PNP BJTs.

[0015] The anode of the unidirectional conductor is the anode of the diode, and the cathode of the unidirectional conductor is the cathode of the diode. The first ends of both the first switching device and the second switching device are the emitters of the PNP BJTs. The second ends of both the first switching device and the second switching device are the collectors of the PNP BJTs. The control ends of both the first switching device and the second switching device are the bases of the PNP BJTs.

[0016] In one embodiment, the conversion module includes an operational amplifier unit, a fourth switching device, and a first resistor. The non-inverting input terminal of the operational amplifier unit is for connecting to the voltage signal. The output terminal of the operational amplifier unit is connected to the control end of the fourth switching device. The first end of the fourth switching device is connected to the first end of the current mirror. The second end of the fourth switching device is respectively connected to the inverting input terminal of the operational amplifier unit and the first end of the first resistor. The second end of the first resistor is grounded.

[0017] In one embodiment, the fourth switching device is an NPN BJT.

[0018] The first end of the fourth switching device is the collector of the NPN BJT, the second end of the fourth switching device is the emitter of the NPN BJT, and the control end of the fourth switching device is the base of the NPN BJT.

[0019] In one embodiment, the load includes a transmission wire and a second resistor. The first end of the transmission wire is connected to the dynamic voltage regulation module, the second end of the transmission wire is connected to the first end of the second resistor, and the second end of the second resistor is grounded.

[0020] In one embodiment, the voltage signal is an analog video signal.

[0021] A second aspect of the embodiments of the present application provides a vehicle-mounted electronic device, including a shooting module and the analog signal transmission circuit as described above. The shooting module is connected to the analog signal transmission circuit, and the analog video signal output by the shooting module is transmitted through the analog signal transmission circuit.

[0022] The beneficial effects of the embodiments of the present application compared with the related technologies are as follows: By converting the voltage signal into a current signal for transmission, the influence brought by noise can be avoided, and the circuit of the present application is relatively simple and the cost is relatively low.

[0023] At the same time, when the voltage at both ends of the load changes, the dynamic voltage regulation module can bear the changed part of the voltage of the load and provide a symmetric working environment for the current mirror to ensure the symmetry of the current mirror. Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of the analog signal transmission circuit provided by an embodiment of the present application;

[0025] Figure 2 It is a schematic circuit diagram of the analog signal transmission circuit provided by an embodiment of the present application;

[0026] Figure 3 It is a schematic structural diagram of the vehicle-mounted electronic device provided by an embodiment of the present application. Detailed Embodiments

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the drawings and 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.

[0028] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0029] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0030] Figure 1 The schematic structural diagram of the analog signal transmission circuit provided by an embodiment of this application is shown. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0031] An analog signal transmission circuit 10 includes: a conversion module 100, a current mirror 200, and a dynamic voltage regulation module 300.

[0032] Wherein, the first end of the conversion module 100 is used to access a voltage signal, and the conversion module 100 is used to convert the voltage signal into a first current signal and output it from the second end of the conversion module 100.

[0033] The first end of the current mirror 200 is connected to the second end of the conversion module 100, the second end of the current mirror 200 is used to connect to the load 20, and the current mirror 200 is used to generate and provide a second current signal to the load 20 according to the first current signal, and the second current signal is equal to the first current signal.

[0034] The dynamic voltage regulation module 300 is connected between the second end of the current mirror 200 and the load 20, and the dynamic voltage regulation module 300 is also connected to the first end of the current mirror 200. The dynamic voltage regulation module 300 is used to control the voltage applied to the current mirror 200 to remain constant by adjusting its own impedance.

[0035] The embodiment of this application can avoid the influence brought by noise by converting the voltage signal into a current signal for transmission, and the circuit of this application is relatively simple and has a low cost.

[0036] At the same time, when the voltage across the load 20 changes, the dynamic voltage regulation module 300 can bear the changing part of the voltage of the load 20, stabilize the working voltage of the current mirror 200, and provide a symmetrical working environment for the current mirror 200 to ensure the symmetry of the current mirror 200.

[0037] In one embodiment, as Figure 2 shown, the current mirror 200 includes a unidirectional conductor D1, a first switching device Q1, and a second switching device Q2.

[0038] The first end of the first switching device Q1 is used to access the driving voltage V2. The second end of the first switching device Q1 is connected to the anode of the unidirectional conductor D1. The cathode of the unidirectional conductor D1 is connected to the second end of the conversion module 100. The control end of the first switching device Q1 is connected to the control end of the second switching device Q2. The first end of the second switching device Q2 is connected to the first end of the first switching device Q1. The second end of the second switching device Q2 is respectively connected to the dynamic voltage regulation module 300 and the control end of the second switching device Q2.

[0039] Through the current mirror 200 composed of two switching devices with interconnected control ends, a second current signal equal to the first current signal can be generated according to the first current signal at the first end of the current mirror 200, so that the first current signal and the second current signal are not affected by factors such as the load 20 and the current remains unchanged.

[0040] The unidirectional conductor D1 can protect the current mirror 200 and prevent the reverse current from affecting the operation of the current mirror 200.

[0041] Among them, the driving voltage V2 can be set according to actual needs.

[0042] In an embodiment, the unidirectional conductor D1 is a diode, and both the first switching device Q1 and the second switching device Q2 are PNP triodes.

[0043] The anode of the unidirectional conductor D1 is the anode of the diode, the cathode of the unidirectional conductor D1 is the cathode of the diode, the first ends of the first switching device Q1 and the second switching device Q2 are both the emitters of the PNP triodes, the second ends of the first switching device Q1 and the second switching device Q2 are both the collectors of the PNP triodes, and the control ends of the first switching device Q1 and the second switching device Q2 are both the bases of the PNP triodes.

[0044] It can be understood that in this embodiment, the current flowing through the first switching device Q1 is equal to the current flowing through the second switching device Q2.

[0045] In an embodiment, as Figure 2 shown, the dynamic voltage regulation module 300 includes a third switching device Q3. The first end of the third switching device Q3 is connected to the second end of the current mirror 200. The second end of the third switching device Q3 is used to be connected to the load 20. The control end of the third switching device Q3 is connected to the first end of the current mirror 200.

[0046] Due to the access of the third switching device Q3, the base of the second switching device Q2 is connected to the collector of the second switching device Q2, making the voltage between the emitter and collector of the first switching device Q1 and the second switching device Q2 relatively constant and the voltage value small. This can maintain the heat generation of the first switching device Q1 and the second switching device Q2 at a very low level and maintain the thermal symmetry of the first switching device Q1 and the second switching device Q2. When the voltage across the load 20 changes, the third switching device Q3 changes accordingly at this time, avoiding this part of the voltage being applied to the second switching device Q2.

[0047] In one embodiment, the third switching device Q3 is a PNP triode. The first end of the third switching device Q3 is the emitter of the PNP triode, the second end of the third switching device Q3 is the collector of the PNP triode, and the control end of the third switching device Q3 is the base of the PNP triode.

[0048] When the third switching device Q3 is a PNP triode, and the control ends of the first switching device Q1 and the second switching device Q2 in the current mirror 200 are both connected to the second end of the second switching device Q2, the voltage between the first end and the second end of the second switching device Q2 can be kept relatively constant and at a small voltage through the third switching device Q3, thereby reducing the heat generation of the second switching device Q2 and ensuring the thermal symmetry of the switching transistors on both sides of the current mirror 200.

[0049] In one embodiment, as Figure 2 shown, the conversion module 100 includes an operational amplifier unit U1, a fourth switching device Q4, and a first resistor R1. The non-inverting input terminal of the operational amplifier unit U1 is used to access a voltage signal. The output terminal of the operational amplifier unit U1 is connected to the control terminal of the fourth switching device Q4. The first end of the fourth switching device Q4 is connected to the first end of the current mirror 200. The second end of the fourth switching device Q4 is respectively connected to the inverting input terminal of the operational amplifier unit U1 and the first end of the first resistor R1. The second end of the first resistor R1 is grounded.

[0050] It should be noted that when the voltage at the non-inverting input terminal of the operational amplifier unit U1 changes continuously due to the voltage signal, the operational amplifier unit U1 can output a corresponding voltage according to the voltage difference between the non-inverting input terminal and the inverting input terminal of the operational amplifier unit U1. The voltage output by the operational amplifier unit U1 can control the on-resistance of the fourth switching device Q4, thereby adjusting the magnitude of the current flowing through the fourth switching device Q4. Finally, the voltage between the non-inverting input terminal and the inverting input terminal of the operational amplifier unit U1 is kept consistent, thereby generating a first current signal. The current mirror 200 can then output a corresponding second current signal according to the first current signal.

[0051] In one embodiment, the fourth switching device Q4 is an NPN triode.

[0052] The first terminal of the fourth switching device Q4 is the collector of the NPN transistor, the second terminal of the fourth switching device Q4 is the emitter of the NPN transistor, and the control terminal of the fourth switching device Q4 is the base of the NPN transistor.

[0053] In some embodiments, the fourth switching device Q4 is a high-speed NPN transistor.

[0054] In one embodiment, as Figure 2 shown, the load 20 includes a transmission wire 21 and a second resistor R2. The first end of the transmission wire 21 is connected to the dynamic voltage regulation module 300, the second end of the transmission wire 21 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is grounded.

[0055] It can be understood that the second end of the transmission wire 21 can also be connected to other devices or modules to receive the second current signal.

[0056] In some embodiments, the resistance values of the first resistor R1 and the second resistor R2 are equal. Exemplarily, the resistance values of the first resistor R1 and the second resistor R2 can both be 75 ohms.

[0057] In some embodiments, the transmission wire 21 is a 75-ohm coaxial transmission line. In one embodiment, the voltage signal is an analog video signal.

[0058] It can be understood that a shooting device such as a camera can output an analog video signal, and the shooting device can be connected to a corresponding display and storage device through the analog signal transmission circuit 10 to transmit the analog video signal through the analog signal transmission circuit 10.

[0059] Since the analog signal transmission circuit 10 has a high driving ability and can achieve the transmission of high-quality analog video signals, the length limit of the transmission wire 21 can be further relaxed.

[0060] Figure 3 The schematic structural diagram of the in-vehicle electronic device provided by an embodiment of the present application is shown. For the convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0061] The in-vehicle electronic device 30 includes a shooting module 40 and the analog signal transmission circuit 10 as described in any of the above embodiments. The shooting module 40 is connected to the analog signal transmission circuit 10, and the analog video signal output by the shooting module 40 is transmitted through the analog signal transmission circuit 10.

[0062] In some embodiments, the in-vehicle electronic device 30 further includes a load 20, and the load 20 may include devices such as a display and a memory.

[0063] Among them, the shooting module 40 includes shooting devices such as cameras, which can be used to obtain the environmental information around the vehicle and transmit the analog video signal to devices such as in-vehicle displays through the analog signal transmission circuit 10, avoiding the influence of noise on the picture quality.

[0064] In addition, when analog video devices are cascaded, the analog signal transmission circuit 10 can make the signal transmit unidirectionally, and there is no need to consider the return path problem in detail for the power supply distribution of each device, and the power supply can be selected more freely.

[0065] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above-mentioned functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiment and will not be described in detail here.

[0066] In the above embodiments, the descriptions of the various embodiments have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0067] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, 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 on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An analog signal transmission circuit, characterized in that: include: A conversion module, wherein a first end of the conversion module is used to receive a voltage signal, and the conversion module is used to convert the voltage signal into a first current signal and output it from a second end of the conversion module; a current mirror, wherein a first end of the current mirror is connected to a second end of the conversion module, a second end of the current mirror is used to connect a load, and the current mirror is used to generate and provide a second current signal to the load according to the first current signal, wherein the second current signal is equal to the first current signal; A dynamic voltage regulation module, wherein the dynamic voltage regulation module is connected between the second end of the current mirror and the load, and the dynamic voltage regulation module is also connected to the first end of the current mirror, and the dynamic voltage regulation module is used to control the voltage applied to the current mirror to remain constant by adjusting its own impedance.

2. The analog signal transmission circuit according to claim 1, characterized in that: The current mirror comprises a unidirectional conductor, a first switch device and a second switch device; The first end of the first switching device is used to access the driving voltage, the second end of the first switching device is connected to the anode of the one-way conductor, the cathode of the one-way conductor is connected to the second end of the conversion module, the control end of the first switching device is connected to the control end of the second switching device, the first end of the second switching device is connected to the first end of the first switching device, and the second end of the second switching device is respectively connected to the dynamic voltage regulation module and the control end of the second switching device.

3. The analog signal transmission circuit according to claim 2, characterized in that: The one-way conductor is a diode, and the first switch device and the second switch device are both PNP transistors; The anode of the one-way conductor is the anode of a diode, the cathode of the one-way conductor is the cathode of a diode, the first end of the first switching device and the first end of the second switching device are both emitters of a PNP transistor, the second end of the first switching device and the second end of the second switching device are both collectors of the PNP transistor, and the control end of the first switching device and the control end of the second switching device are both bases of the PNP transistor.

4. The analog signal transmission circuit according to claim 2, characterized in that: The dynamic voltage regulation module includes a third switch device, a first end of the third switch device is connected to the second end of the current mirror, the second end of the third switch device is used to connect to the load, and a control end of the third switch device is connected to the first end of the current mirror.

5. The analog signal transmission circuit according to claim 4, characterized in that: The third switch device is a PNP transistor, the first end of the third switch device is the emitter of the PNP transistor, the second end of the third switch device is the collector of the PNP transistor, and the control end of the third switch device is the base of the PNP transistor.

6. The analog signal transmission circuit according to any one of claims 1 to 5, characterized in that: The conversion module includes an operational amplifier unit, a fourth switching device and a first resistor, the non-phase input terminal of the operational amplifier unit is used to access the voltage signal, the output terminal of the operational amplifier unit is connected to the control terminal of the fourth switching device, the first terminal of the fourth switching device is connected to the first terminal of the current mirror, the second terminal of the fourth switching device is respectively connected to the inverting input terminal of the operational amplifier unit and the first terminal of the first resistor, and the second terminal of the first resistor is grounded.

7. The analog signal transmission circuit according to claim 6, characterized in that: The fourth switch device is an NPN transistor; The first end of the fourth switch device is the collector of the NPN transistor, the second end of the fourth switch device is the emitter of the NPN transistor, and the control end of the fourth switch device is the base of the NPN transistor.

8. The analog signal transmission circuit according to any one of claims 1 to 5, characterized in that: The load includes a transmission wire and a second resistor, a first end of the transmission wire is connected to the dynamic voltage regulation module, a second end of the transmission wire is connected to a first end of the second resistor, and a second end of the second resistor is grounded.

9. The analog signal transmission circuit according to any one of claims 1 to 5, characterized in that: The voltage signal is an analog video signal.

10. An in-vehicle electronic device, characterized in that: It comprises a shooting module and the analog signal transmission circuit according to any one of claims 1 to 9, the shooting module is connected to the analog signal transmission circuit, and the analog video signal output by the shooting module is transmitted through the analog signal transmission circuit.

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