Analog voltage conversion circuit and system

Abstract

The application relates to an analog voltage conversion circuit and system. The circuit comprises a first resistance unit, a first operational amplifier, a photoelectric coupling unit and a transimpedance amplification circuit, the photoelectric coupling unit comprising a light emitter, a first light receiver and a second light receiver; wherein the first end of the first resistance unit is configured to access a first voltage signal; the second end of the first resistance unit is connected with the inverting input end of the first operational amplifier and the first end of the first light receiver; the non-inverting input end of the first operational amplifier is connected with the second end of the first light receiver and grounded, the output end of the first operational amplifier is connected with the first end of the light emitter, and the second end of the light emitter is connected with a power supply voltage; the two ends of the second light receiver are connected with the input end of the transimpedance amplification circuit, and the output end of the transimpedance amplification circuit is configured to output a second voltage signal. The circuit can realize stable isolation conversion of the voltage signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of analog electronic circuit, in particular to an analog voltage conversion circuit and system. BACKGROUND

[0002] With the development of analog electronic circuit technology, analog electronic circuit technology is used in many application fields. In medical equipment, a single-chip microcomputer control system realizes data interaction with external board cards and other devices through a bus. In the connection between the single-chip microcomputer control system and the board card, isolation is an important design consideration. Isolation not only protects the single-chip microcomputer control system from possible electrical interference and damage on the board card, but also improves the stability and reliability of the entire system.

[0003] However, in the conventional technology, a bus-type digital-to-analog converter (DAC) is used to isolate the bus signal of the single-chip microcomputer control system through a digital isolation circuit to achieve this purpose. However, low-voltage bus signals are more susceptible to interference, so voltage signal isolation conversion cannot be stably performed. SUMMARY

[0004] Therefore, it is necessary to provide an analog voltage conversion circuit and system that can improve the signal isolation conversion effect of the board card and the single-chip microcomputer control system to solve the above technical problems.

[0005] An analog voltage conversion circuit, the circuit comprising: a first resistance unit, a first operational amplifier, an optoelectronic coupling unit, and a transimpedance amplification circuit, the optoelectronic coupling unit comprising a light emitter, a first light receiver, and a second light receiver; wherein,

[0006] The first end of the first resistance unit is configured to access a first voltage signal;

[0007] The second end of the first resistance unit is connected to the inverting input terminal of the first operational amplifier and the first end of the first light receiver;

[0008] The non-inverting input terminal of the first operational amplifier is connected to the second end of the first light receiver and grounded, the output terminal of the first operational amplifier is connected to the first end of the light emitter, and the second end of the light emitter is connected to a power supply voltage;

[0009] The two ends of the second light receiver are connected to the input terminal of the transimpedance amplification circuit, and the output terminal of the transimpedance amplification circuit is configured to output a second voltage signal.

[0010] In some embodiments, the transimpedance amplification circuit comprises a second operational amplifier and a second resistance unit; wherein,

[0011] The first end of the second light receiver is connected to the inverting input end of the second operational amplifier and the first end of the second resistance unit, and the second end of the second light receiver is connected to the non-inverting input end of the second operational amplifier and grounded.

[0012] The output end of the second operational amplifier is connected to the second end of the second resistance unit and is configured to output a second voltage signal.

[0013] In some embodiments, the photoelectric coupling unit employs a linear photoelectric coupler.

[0014] In some embodiments, the light emitter employs a light-emitting diode or a light-emitting triode.

[0015] In some embodiments, the first light receiver employs a photodiode or a photo triode, and / or the second light receiver employs a photodiode or a photo triode.

[0016] In some embodiments, the light emitter is a light-emitting diode, the first light receiver is a first photodiode, and the second light receiver is a second photodiode; wherein,

[0017] The second end of the first resistance unit is connected to the inverting input end of the first operational amplifier and the negative electrode of the first photodiode.

[0018] The non-inverting input end of the first operational amplifier is connected to the positive electrode of the first photodiode and grounded, the output end of the first operational amplifier is connected to the negative electrode of the light-emitting diode, and the positive electrode of the light-emitting diode is connected to a power supply voltage.

[0019] The negative electrode of the second photodiode is connected to the inverting input end of the second operational amplifier and the first end of the second resistance unit, and the positive electrode of the second photodiode is connected to the non-inverting input end of the second operational amplifier and grounded.

[0020] In some embodiments, the first resistance unit includes one or more resistance elements, and / or the first resistance unit includes one or more resistance elements.

[0021] In some embodiments, the resistance value of the first resistance unit is adjustable, and / or the resistance value of the second resistance unit is adjustable.

[0022] In some embodiments, the following conditions are met between the resistance value of the first resistance unit, the resistance value of the second resistance unit, the first voltage signal, and the second voltage signal:

[0023]

[0024] wherein VOUT represents the second voltage signal, VIN represents the first voltage signal, K represents the ratio of the current of the second light receiver to the current of the first light receiver, K is a constant, R1 represents the resistance value of the first resistance unit, and R2 represents the resistance value of the second resistance unit.

[0025] In a second aspect, an analog voltage conversion system is provided, the system comprising a board circuit, a microcontroller control system, and an analog voltage conversion circuit according to any one of the first aspects, wherein the analog voltage conversion circuit is used to isolate the voltage signal of the microcontroller control system from the voltage signal of the board circuit.

[0026] The above-described analog voltage conversion circuit and system, using the connection method of the embodiment of this application, ensures that when the first operational amplifier has ideal performance, no current flows into its input terminal. All current flowing through the first resistor unit will flow through the first photodetector. The current flowing through the first photodetector depends only on the input first voltage signal and the resistance value of the first resistor unit, thus exhibiting a very excellent linear relationship between the input first voltage signal and the current of the first photodetector. Consequently, the light output of the light-emitting diode will also become stable and linearized, and the current flowing through the second photodetector will also remain stable and linearized. Therefore, after the second photodetector is connected to the transimpedance amplifier circuit, the output second voltage signal also has excellent stability and linearity characteristics with the input first voltage signal, enabling stable isolation and conversion of voltage signals between the microcontroller control system and the board. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an analog voltage conversion circuit in some embodiments;

[0028] Figure 2 This is a schematic diagram of the current flow of the circuit on the first light receiver side of the optocoupler unit in some embodiments;

[0029] Figure 3 This is a schematic diagram of the current flow on the second photodetector side of the optocoupler unit in some embodiments;

[0030] Figure 4 This is a schematic diagram of the structure of an analog voltage conversion system in some embodiments. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] In some embodiments, such as Figure 1 As shown, an analog voltage conversion circuit is provided, which includes: a first resistor unit 100, a first operational amplifier U1, an optocoupler unit 200, and a transimpedance amplifier circuit 300. The optocoupler unit 200 includes a light emitter 201, a first light receiver 202, and a second light receiver 203; wherein,

[0033] The first end of the first resistance unit 100 is configured to access the first voltage signal VIN;

[0034] The second end of the first resistance unit 100 is connected to the inverting input end U1- of the first operational amplifier U1, and the first end of the first light receiver 202;

[0035] The non-inverting input end U1+ of the first operational amplifier U1 is connected to the second end of the first light receiver 202 and the ground GND, the output end of the first operational amplifier U1 is connected to the first end of the light emitter 201, and the second end of the light emitter 201 is connected to the power supply voltage VCC;

[0036] The two ends of the second light receiver 203 are connected to the input end of the transimpedance amplification circuit 300, and the output end of the transimpedance amplification circuit 300 is configured to output the second voltage signal VOUT.

[0037] Exemplarily, the optical coupling unit 200 can include an optical coupler (OP), which can also be referred to as an optical isolator. For example, a linear optical coupler can be used, in which the light receiver generates a leakage current that linearly changes with the light output of the light emitter. Using a linear optical coupler can improve the stability of voltage conversion, making the voltage linearization between the two ends of the circuit stronger.

[0038] Exemplarily, the light emitter 200 can use a semiconductor light-emitting element such as a light-emitting diode (LED) or a light-emitting triode, without particular limitation.

[0039] Exemplarily, the first light receiver 202 can use a photodiode or a phototriode, and the second light receiver 203 can also use a photodiode or a phototriode, without particular limitation. In the linear optical coupler OP, the two light receivers are closely matched, and the ratio between the current flowing through the first light receiver 202 and the current flowing through the second light receiver 203 is a constant, which can be different according to the selection of the optical coupler.

[0040] Below, please refer to Figure 2 , for the convenience of illustration and viewing, the optical coupling unit 200 in Figure 1 is split into the circuit on the first light receiver 201 side of the optical coupling unit and the circuit on the second light receiver 202 side. Figure 2 A current flow direction schematic diagram of the circuit on the first light receiver side of the optical coupling unit in some embodiments is shown.

[0041] In some embodiments, refer to Figure 1 and Figure 2As shown, since the linear characteristics of the light emitting diode and the photodiode are better, and the structure is simpler and the cost is lower, in the embodiment, the light emitting device can be a light emitting diode LED1, the first light receiving device can be a first photodiode PD1, and the second light receiving device can be a second photodiode PD2.

[0042] Specifically, the second end of the first resistance unit 100 is connected to the inverting input end U1- of the first operational amplifier U1 and the negative electrode of the first photodiode PD1; the non-inverting input end U1+ of the first operational amplifier U1 is connected to the positive electrode of the first photodiode PD1 and grounded GND, the output end of the first operational amplifier U1 is connected to the negative electrode of the light emitting diode LED1, and the positive electrode of the light emitting diode LED1 is connected to the power supply voltage VCC; the negative electrode of the second photodiode PD2 is connected to the inverting input end U2- of the second operational amplifier U2 and the first end of the second resistance unit 301, and the positive electrode of the second photodiode PD2 is connected to the non-inverting input end U2+ of the second operational amplifier U2 and grounded GND.

[0043] From Figure 2 It can be seen that when the voltage of the first voltage signal VIN increases, due to the characteristics of the first operational amplifier U1, the voltage of the inverting input end U1- of the first operational amplifier U1 will be higher than 0V, at this time, the first operational amplifier U1 amplifies the increasing part, causing the current I F to increase, and the current I F increases, causing the current I PD1 flowing through the first light receiving device to increase. Since the first photodiode PD1 adopts the connection mode of the embodiment of the present application, the current I PD1 pulls the potential of the inverting input end U1- of the operational amplifier U1 back to the same as GND, that is, the potential 0V or basically close to 0V. In the case of ideal performance of the operational amplifier U1, no current flows into its input end, therefore, all the current flowing through the first resistance unit 100 (R1 in the figure) will flow through the first photodiode PD1. Because the inverting input end U1- of the operational amplifier U1 inputs 0V or basically close to 0V, the current flowing through the first resistance unit 100 (R1 in the figure) can be considered to be equal to the current flowing through the first photodiode PD1, that is, equal to

[0044] Therefore, the current I PD1 only depends on the input first voltage signal VIN and the resistance value of the first resistance unit 100 (resistor R1), thereby presenting a very excellent linear relationship between the input first voltage signal VIN and the photodiode current I PD1 .

[0045] Therefore, through the stable and linearized current I PD1, the light output of the light emitting diode LED1 will also become stable and linearized, so the current I PD2 will also maintain the trend of stability and linearization. Since the current I PD2 will also maintain the trend of stability and linearization, the second voltage signal VOUT output by the second photodiode PD2 after connecting the transimpedance amplification circuit also has excellent stability and linearization characteristics between the input first voltage signal VIN, and the linear coefficient can be converted to only rely on the fixed properties of the optocoupler unit and the relationship between the first resistance unit (resistor R1) and the transimpedance (for example, resistor R2) of the transimpedance amplification circuit, and further, the single-chip microcomputer control system and the stable isolation conversion of the voltage signal between the board card can be realized.

[0046] In some embodiments, the transimpedance amplification circuit 300 can include a second operational amplifier U2 and a second resistance unit 301; wherein the first end of the second light receiver 203 is connected to the inverting input end U2- of the second operational amplifier U2 and the first end of the second resistance unit 301, and the second end of the second light receiver 203 is connected to the non-inverting input end U2+ of the second operational amplifier U2 and the ground GND; the output end of the second operational amplifier U2 is connected to the second end of the second resistance unit 301, and is configured to output the second voltage signal VOUT. In other embodiments, other structures of transimpedance amplification circuits can also be used as long as they have the function of transimpedance amplification.

[0047] In this embodiment, referring to Figure 3 , it is Figure 3 a schematic diagram of the current flow on the second light receiver side of the optocoupler unit in some embodiments. The transimpedance amplification circuit 300 composed of the second operational amplifier U2 and the second resistance unit 301 (resistor R2) of the above structure is connected to the second light receiver 203 (for example, PD2 in the figure) side of the optocoupler unit 200, and the current I PD2 flowing through the second photodiode PD2 is converted into the second voltage signal VOUT, wherein VOUT=I PD2 *R2.

[0048] Therefore, the ratio between the first voltage signal VIN and the second voltage signal VOUT will satisfy the following formula:

[0049]

[0050] Further, since the physical structure of the packaged linear optocoupler determines the relative amount of light falling on the two photodiodes, thereby determining the ratio of the photodiode current. This leads to its very stable operation over time and temperature. Therefore, the current ratio flowing through the two photodiodes can be represented as a constant K, wherein

[0051] In other words, the ratio between the input first voltage signal VIN and the output second voltage signal VOUT can ultimately satisfy the following correlation:

[0052]

[0053] Therefore, the relationship between the first voltage signal VIN and the second voltage signal VOUT is constant and linear, and is independent of the light output characteristics of the LED. The gain of this voltage conversion circuit can be determined by the ratio of the resistance values ​​of the first resistor unit 100 to the second resistor unit 301. The parameter K can be limited by the manufacturer during the production process of the linear optocoupler and is specified in the datasheet. Therefore, the gain can be controlled to some extent by selecting linear optocouplers with different parameters K.

[0054] In some embodiments, the first resistor unit 100 may include one or more resistors, and the resistance value of the first resistor unit 100 can be flexibly adjusted by changing the number of resistors or by connecting them in series or parallel. In other embodiments, the second resistor unit 301 may also include one or more resistors, and the resistance value of the second resistor unit 301 can be flexibly adjusted by changing the number of resistors or by connecting them in series or parallel.

[0055] In some embodiments, the first resistor unit 100 and the second resistor unit 301 may also be resistive elements with adjustable resistance values, such as variable resistors. This improves the flexibility of adjusting the gain of the voltage conversion circuit.

[0056] Below, this application also provides an analog voltage conversion system, with reference to... Figure 4 As shown, Figure 4 A schematic diagram of an analog voltage conversion system in some embodiments is shown. The analog voltage conversion system includes a board circuit 20, a microcontroller control system 30, and an analog voltage conversion circuit 10. The analog voltage conversion circuit 10 is connected between the board circuit 20 and the microcontroller control system 30, and is used to isolate the voltage signal of the microcontroller control system from the voltage signal of the board circuit.

[0057] For details on how the analog voltage conversion circuit 10 achieves stable linear isolation conversion between voltage signals, please refer to the description of the above embodiments, which will not be repeated here.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] In addition, the term "and / or" herein merely describes an associated relationship, which means that there can be three relationships, for example, A and / or B can represent three cases: A exists alone, A and B exist together, and B exists alone. In addition, the characters herein generally represent an "or" relationship between the preceding and following associated objects.

[0060] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. An analog voltage conversion circuit, the circuit comprising: The first resistance unit, the first operational amplifier, the photoelectric coupling unit, and the transimpedance amplification circuit, the photoelectric coupling unit comprising a light emitter, a first light receiver and a second light receiver; wherein, The first end of the first resistance unit is configured to access a first voltage signal; The second end of the first resistance unit is connected to the inverting input terminal of the first operational amplifier and the first end of the first light receiver; The non-inverting input terminal of the first operational amplifier is connected to the second end of the first light receiver and grounded, and the output terminal of the first operational amplifier is connected to the first end of the light emitter, and the second end of the light emitter is connected to a power supply voltage; The two ends of the second light receiver are connected to the input terminal of the transimpedance amplification circuit, and the output terminal of the transimpedance amplification circuit is configured to output a second voltage signal.

2. The circuit of claim 1, wherein, The transimpedance amplification circuit comprises a second operational amplifier and a second resistance unit; wherein, The first end of the second resistance unit is connected to the inverting input terminal of the second operational amplifier and the first end of the second resistance unit, and the second end of the second light receiver is connected to the non-inverting input terminal of the second operational amplifier and grounded; The output terminal of the second operational amplifier is connected to the second end of the second resistance unit and is configured to output the second voltage signal.

3. The circuit of claim 1, wherein, The photoelectric coupling unit adopts a linear photoelectric coupler.

4. The circuit of claim 1, wherein, The light emitter adopts a light-emitting diode or a light-emitting triode.

5. The circuit of claim 1, wherein, The first light receiver adopts a photodiode or a photoelectric triode, and / or the second light receiver adopts a photodiode or a photoelectric triode.

6. The circuit of claim 2, wherein, The light emitter is a light-emitting diode, the first light receiver is a first photodiode, and the second light receiver is a second photodiode; wherein, The second end of the first resistance unit is connected to the inverting input terminal of the first operational amplifier and the negative electrode of the first photodiode; The non-inverting input terminal of the first operational amplifier is connected to the positive electrode of the first photodiode and grounded, and the output terminal of the first operational amplifier is connected to the negative electrode of the light-emitting diode, and the positive electrode of the light-emitting diode is connected to a power supply voltage; The negative electrode of the second photodiode is connected to the inverting input terminal of the second operational amplifier and the first end of the second resistance unit, and the positive electrode of the second photodiode is connected to the non-inverting input terminal of the second operational amplifier and grounded.

7. The circuit of claim 2, wherein, The first resistance unit comprises one or more resistance elements, and / or the first resistance unit comprises one or more resistance elements.

8. The circuit of claim 2, wherein, The resistance value of the first resistance unit is adjustable, and / or the resistance value of the second resistance unit is adjustable.

9. The circuit of claim 2, wherein, The resistance value of the first resistance unit, the resistance value of the second resistance unit, the first voltage signal, and the second voltage signal satisfy the following conditions: Wherein, VOUT represents the second voltage signal, VIN represents the first voltage signal, K represents the ratio of the current of the second light receiver to the current of the first light receiver, K is a constant, R1 represents the resistance value of the first resistance unit, and R2 represents the resistance value of the second resistance unit.

10. An analog voltage conversion system, characterized by, The system comprises a board card circuit, a single-chip microcomputer control system, and the analog voltage conversion circuit according to any one of claims 1 to 9, which is used to isolate the voltage signal of the single-chip microcomputer control system from the voltage signal of the board card circuit.

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