Current source and digital calibration device

Abstract

The application provides a current source, and relates to the technical field of current sources. The current source comprises a reference circuit, a bipolar voltage generation circuit and a voltage conversion circuit connected in sequence. The reference circuit comprises a reference voltage source. The reference circuit is used for outputting a reference voltage to the bipolar voltage generation circuit by using the reference voltage source. The model of the reference voltage source comprises ADR512. The bipolar voltage generation circuit is used for generating a bipolar voltage. The voltage conversion circuit is used for converting the bipolar voltage into a current and outputting. The embodiment of the application can output a stable reference voltage by using the reference voltage, thereby avoiding the influence of reference voltage fluctuation on the stability of output current, and reducing the influence of low temperature by the characteristics of the reference voltage source, improving the stability of output current, and effectively meeting the accuracy requirement of output current.

Description

Technical Field

[0001] This application relates to the field of current source technology, and more specifically, to a current source and a digital calibration device. Background Technology

[0002] Digital calibration refers to a technique that uses digital signal processing technology, digital logic, or microcontrollers (MCU / DSP) to detect, compensate for, and correct deviations, nonlinearities, gain errors, offset errors, etc., of sensors, measuring instruments, analog circuits, or systems in order to improve their measurement accuracy, consistency, or reliability.

[0003] In digital calibration, it is often necessary to provide current using a current source. However, the current output of existing current sources is unstable and prone to drift at low temperatures, making it difficult to meet the accuracy requirements of digital calibration. Utility Model Content

[0004] This application provides a current source and a digital calibration device, which can solve the problems that existing current sources are unstable and easily affected by low temperatures, making it difficult to meet the accuracy requirements of digital calibration.

[0005] To achieve this objective, the embodiments of this application provide the following solutions.

[0006] According to one aspect of the embodiments of this application, a current source is provided, including a reference circuit, a bipolar voltage generation circuit, and a voltage conversion circuit connected in sequence. The reference circuit includes a reference voltage source, and the reference circuit is used to output a reference voltage to the bipolar voltage generation circuit using the reference voltage source. The reference voltage source includes an ADR512. The bipolar voltage generation circuit is used to generate a bipolar voltage; The voltage conversion circuit is used to convert the bipolar voltage into current and output it.

[0007] In one possible implementation, the reference circuit includes an eleventh resistor and an eighth capacitor. The first terminal of the reference voltage source is connected to the second terminal of the eleventh resistor and the first terminal of the eighth capacitor. The first terminal of the eleventh resistor is connected to a first power supply. The second terminal of the eighth capacitor is grounded, and the second terminal of the reference voltage source is grounded.

[0008] In one possible implementation, the bipolar voltage generation circuit includes a non-inverting amplifier circuit with a first operational amplifier, a first resistor, and a second resistor. The non-inverting input of the first operational amplifier is connected to the output of the reference circuit. The inverting input of the first operational amplifier is connected to the second end of the first resistor and the first end of the second resistor. The second end of the second resistor is grounded. The first end of the first resistor is connected to the output of the first operational amplifier. The power supply of the first operational amplifier is connected to a second power supply.

[0009] In one possible implementation, the bipolar voltage generation circuit includes an inverting amplifier circuit with a second operational amplifier, a third resistor, a fourth resistor, and a fifth resistor. The non-inverting input of the second operational amplifier is connected to the second terminal of the third resistor, the first terminal of the third resistor is grounded, the inverting input of the second operational amplifier is connected to the first terminal of the fourth resistor and the second terminal of the fifth resistor, the second terminal of the fourth resistor is connected to the output of the reference circuit, and the first terminal of the fifth resistor is connected to the output of the second operational amplifier.

[0010] In one possible implementation, the voltage conversion circuit includes a digital potentiometer and a current source circuit, wherein the first voltage input terminal of the digital potentiometer is connected to the output terminal of the first operational amplifier, and the second voltage input terminal of the digital potentiometer is connected to the output terminal of the second operational amplifier; The voltage output terminal of the digital potentiometer is connected to the input terminal of the current source circuit.

[0011] In one possible implementation, the second power supply includes a positive power supply and a negative power supply, and the voltage conversion circuit includes a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. The positive power supply is connected to the first terminal of the fifth capacitor, the second terminal of the sixth capacitor, and the operating voltage terminal of the digital potentiometer. The second terminals of the fifth capacitor and the second terminals of the sixth capacitor are grounded. The negative power supply is connected to the first terminal of the third capacitor, the first terminal of the fourth capacitor, and the common ground terminal of the digital potentiometer, while the second terminals of the third capacitor and the second terminals of the fourth capacitor are grounded.

[0012] In one possible implementation, the current source circuit includes a third operational amplifier, a fourth operational amplifier, a first capacitor, a sixth resistor, a seventh resistor, and a tenth resistor. The non-inverting input of the third operational amplifier is connected to the output of the digital potentiometer, and the inverting input is connected to the first terminal of the first capacitor and the first terminal of the sixth resistor. The second terminal of the sixth resistor is connected to the second terminal of the first capacitor, the first terminal of the seventh resistor, and the non-inverting input of the fourth operational amplifier. The second terminal of the seventh resistor is connected to the output of the fourth operational amplifier. The inverting input of the fourth operational amplifier is connected to the second terminal of the tenth resistor, and the first terminal of the tenth resistor is grounded.

[0013] In one possible implementation, the current source circuit further includes an eighth resistor, a ninth resistor, and a second capacitor. The first end of the eighth resistor is connected to the second end of the seventh resistor. The second end of the eighth resistor is connected to the second end of the ninth resistor, the second end of the second capacitor, the output terminal of the fourth operational amplifier, and the second end of the second capacitor. The first end of the ninth resistor is connected to the second end of the tenth resistor, the inverting input terminal of the fourth operational amplifier, and the first end of the second capacitor.

[0014] According to one aspect of the embodiments of this application, a digital calibration device is provided, including a sensor and a current source as described above, wherein the output terminal of the current source is connected to the sensor for outputting current to the sensor.

[0015] In one possible implementation, a signal acquisition circuit is included, which is connected to the sensor and is used to acquire voltage signals.

[0016] The beneficial effects of the technical solutions provided in this application are: The current source provided in this application includes a reference circuit, a bipolar voltage generation circuit, and a voltage conversion circuit connected in sequence. The reference circuit includes a reference voltage source, which is used to output a reference voltage to the bipolar voltage generation circuit. The reference voltage source may be an ADR512. The bipolar voltage generation circuit generates a bipolar voltage. The voltage conversion circuit converts the bipolar voltage into current and outputs it. This embodiment of the application can output a stable reference voltage using the reference voltage, thereby avoiding the impact of reference voltage fluctuations on the stability of the output current. Furthermore, the characteristics of the reference voltage source can reduce the impact of low temperatures, improve the stability of the output current, and effectively meet the accuracy requirements of the output current. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below.

[0018] Figure 1 A structural diagram of the current source provided in the embodiments of this application; Figure 2 A flowchart illustrating the output current of the current source provided in this application embodiment; Figure 3 Circuit diagrams of the reference circuit and bipolar voltage generation circuit provided for embodiments of this application; Figure 4 A circuit diagram of a digital potentiometer provided in an embodiment of this application; Figure 5 A circuit diagram of a current source circuit provided in an embodiment of this application; Figure 6 Circuit diagram of the interface provided in the embodiments of this application; Figure 7 This is a structural diagram of the digital calibration device provided in an embodiment of this application.

[0019] Label Explanation: U3, reference voltage source; R11, eleventh resistor; C8, eighth capacitor; R2, second resistor; U1.1, First operational amplifier; R1, First resistor; R3, Third resistor; R4, Fourth resistor; R5, Fifth resistor; U1.2, Second operational amplifier; C4, Fourth capacitor; C3, Third capacitor; C5, Fifth capacitor; C6, Sixth capacitor; U2, Digital potentiometer; U1.3, Third operational amplifier; U1.4, Fourth operational amplifier; R6, Sixth resistor; R7, Seventh resistor; R8, Eighth resistor; C1, First capacitor; R9, Ninth resistor; R10, Tenth resistor; C2, Second capacitor; R12, Twelfth resistor; H1, Interface. Detailed Implementation

[0020] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0021] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the terms “comprising” and “including” as used in embodiments of this application mean that the corresponding feature can be implemented as the presented feature, information, data, step, operation, element, and / or component, but do not exclude implementation as other features, information, data, step, operation, element, component, and / or combinations thereof supported by the art. It should be understood that when we say that an element is “connected” or “coupled” to another element, the one element can be directly connected or coupled to the other element, or it can mean that the one element and the other element establish a connection relationship through an intermediate element. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein indicates at least one of the items defined by the term; for example, “A and / or B” indicates implementation as “A,” or implementation as “A,” or implementation as “A and B.”

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0023] The technical solutions of this utility model and their effects are described below through several exemplary embodiments. It should be noted that the following embodiments can be referenced, borrowed from, or combined with each other. Identical terms, similar features, and similar implementation steps in different embodiments will not be repeated.

[0024] The current source and digital calibration device provided in this application are intended to solve at least one technical problem existing in the prior art.

[0025] This application provides a current source, such as... Figures 1-6 As shown, the current source includes a reference circuit, a bipolar voltage generation circuit, and a voltage conversion circuit connected in sequence. The reference circuit includes a reference voltage source U3, which is used to output a reference voltage to the bipolar voltage generation circuit. The reference voltage source U3 is model ADR512. The bipolar voltage generation circuit generates a bipolar voltage. The voltage conversion circuit converts the bipolar voltage into current and outputs it. By outputting a high-precision reference voltage through the reference voltage source U3, the impact of reference voltage variations on the bipolar voltage generation circuit and the voltage conversion circuit is reduced, improving the stability and accuracy of the output current. Furthermore, the reference voltage source U3 has the advantages of low temperature coefficient and ultra-low noise, and can continuously output a stable reference voltage, avoiding deviations in subsequent voltage regulation and current output due to reference fluctuations, providing a core reference for the stability of the entire circuit.

[0026] In one embodiment, the reference voltage source U3 can be an ADR512, which outputs a high-precision reference voltage of 1.2V. Alternatively, the reference voltage source U3 can be a TPR43xQ, AD584, MAX6033, or other chips capable of outputting high-precision reference voltages.

[0027] Optionally, the bipolar voltage generation circuit can output two voltage signals with different polarities, and the voltage conversion circuit outputs current based on the voltage values ​​of these two voltage signals.

[0028] Optionally, the reference circuit includes an eleventh resistor R11 and an eighth capacitor C8. The first terminal of the reference voltage source U3 is connected to the second terminal of the eleventh resistor R11 and the first terminal of the eighth capacitor C8. The first terminal of the eleventh resistor R11 is connected to the first power supply. The second terminal of the eighth capacitor C8 is grounded, and the second terminal of the reference voltage source U3 is grounded.

[0029] In one embodiment, the first power supply outputs a DC voltage of 15V, the reference voltage source U3 is an ADR512, and the reference circuit sets the bias current through the eleventh resistor R11.

[0030] Optionally, the bipolar voltage generation circuit includes a non-inverting amplifier circuit with a first operational amplifier U1.1, a first resistor R1, and a second resistor R2. The non-inverting input terminal of the first operational amplifier U1.1 is connected to the output terminal of the reference circuit, the inverting input terminal of the first operational amplifier U1.1 is connected to the second terminal of the first resistor R1 and the first terminal of the second resistor R2, the second terminal of the second resistor R2 is grounded, the first terminal of the first resistor R1 is connected to the output terminal of the first operational amplifier U1.1, and the power supply terminal of the first operational amplifier U1.1 is connected to a second power supply.

[0031] Optionally, the voltage signal output by the first operational amplifier U1.1 can be adjusted by setting the ratio of the first resistor R1 and the second resistor R2. Specifically, the voltage value VA of the voltage signal output by the first operational amplifier U1.1 is equal to the output voltage of the reference circuit × (1 + the resistance value of the first resistor R1 / the resistance value of the second resistor R2), and the output voltage of the reference circuit can be 1.2V.

[0032] Optionally, the bipolar voltage generation circuit includes an inverting amplifier circuit with a second operational amplifier U1.2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The non-inverting input terminal of the second operational amplifier U1.2 is connected to the second terminal of the third resistor R3, the first terminal of the third resistor R3 is grounded, the inverting input terminal of the second operational amplifier U1.2 is connected to the first terminal of the fourth resistor R4 and the second terminal of the fifth resistor R5, the second terminal of the fourth resistor R4 is connected to the output terminal of the reference circuit, and the first terminal of the fifth resistor R5 is connected to the output terminal of the second operational amplifier U1.2.

[0033] Optionally, the gain of the inverting amplifier circuit can be set by adjusting the ratio of the fourth resistor R4 to the fifth resistor R5. The voltage value VB of the output voltage signal of the inverting amplifier circuit is equal to the output voltage of the reference circuit × (− the resistance value of the fifth resistor R5 / the resistance value of the fourth resistor R4).

[0034] Optionally, the second power supply can input a positive voltage signal to the positive power supply terminal of the first operational amplifier U1.1 and a negative voltage signal to the negative power supply terminal of the second operational amplifier U1.2. There can be two second power supplies, each outputting a positive and a negative voltage signal respectively, or there can be one power supply that outputs both positive and negative voltage signals simultaneously. The second power supply and the first power supply can also be the same power supply.

[0035] Optionally, the second operational amplifier U1.2 and the first operational amplifier U1.1 can have the same model number or belong to the same operational amplifier. The voltage signals output by the non-inverting amplifier circuit and the inverting amplifier circuit can have the same voltage value but opposite polarities.

[0036] In one embodiment, the first operational amplifier U1.1 and the second operational amplifier U1.2 can be a 4-channel operational amplifier OPA4354AIPWR. This 4-channel operational amplifier features low offset voltage and rail-to-rail output characteristics. When used in conjunction with the ADR512, it can further reduce the temperature coefficient of the output voltage, reduce current output fluctuations caused by temperature changes or device errors, and ensure the stability of the voltage amplification and current conversion process. When the current source is operating, a 1.2V reference voltage is fed into the two channels U1.1 and U1.2 of the 4-channel operational amplifier OPA4354AIPWR, forming a non-inverting amplifier circuit and an inverting amplifier circuit respectively, generating bipolar adjustable voltages VA (positive) and VB (negative). VA (positive) determines the maximum positive output current range of the voltage conversion circuit, and VB (negative) determines the maximum negative output current range. Specifically, the gain of both the first operational amplifier U1.1 and the second operational amplifier U1.2 is ±11.5, ultimately outputting a bipolar adjustable voltage of ±13.8V to provide positive and negative voltage references for the current source.

[0037] Optionally, the voltage conversion circuit includes a digital potentiometer U2 and a current source circuit. The first voltage input terminal of the digital potentiometer U2 is connected to the output terminal of the first operational amplifier U1.1, and the second voltage input terminal of the digital potentiometer U2 is connected to the output terminal of the second operational amplifier U1.2. The voltage output terminal of the digital potentiometer U2 is connected to the input terminal of the current source circuit.

[0038] Optionally, the digital potentiometer U2 can have a command receiving port to receive current control commands and output the corresponding current upon receiving the command. The magnitude of the current value is controlled through the command receiving port.

[0039] In one embodiment, the digital potentiometer U2 can be model AD5293, which boasts an industry-leading ±1% resistance tolerance, far exceeding the ±20% tolerance level of conventional digital potentiometers U2, effectively reducing resistance mismatch errors. The digital potentiometer U2 receives programming code (D, decimal 0-1023) via an SPI-compatible serial interface H1 (the SPI communication protocol interface H1 of the digital potentiometer U2), and generates a voltage divider voltage VW (the voltage at port W) based on the voltage signal VA output from the non-inverting amplifier circuit and the voltage signal VB output from the inverting amplifier circuit. The specific calculation formula is VW = ((D × (VA − VB)) / 1024) + VB. The 10-bit resolution of the AD5293 determines the fine adjustment capability of VW, thereby controlling the accuracy of the current output. The digital potentiometer U2 can also be model TPL0501-100DCNR, AD5160BRJZ10-RL7, EL16-EM-3C, or other models capable of precisely controlling the output voltage.

[0040] Optionally, the second power supply includes a positive power supply and a negative power supply. The voltage conversion circuit includes a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6. The positive power supply is connected to the first terminal of the fifth capacitor C5, the second terminal of the sixth capacitor C6, and the operating voltage terminal of the digital potentiometer U2. The second terminals of the fifth capacitor C5 and the sixth capacitor C6 are grounded. The negative power supply is connected to the first terminal of the third capacitor C3, the first terminal of the fourth capacitor C4, and the common ground terminal of the digital potentiometer U2. The second terminals of the third capacitor C3 and the second terminal of the fourth capacitor C4 are grounded. By using the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, and the sixth capacitor C6 to filter high-frequency signals in the positive and negative power supplies, high-frequency signals are prevented from affecting the digital potentiometer U2.

[0041] Optionally, the current source may also be provided with an interface H1, to which the first power supply, the second power supply, and the digital potentiometer U2 are connected. The first current source and the second current source can supply power to the reference circuit, the bipolar voltage generation circuit, and the voltage conversion circuit through the interface H1. The digital potentiometer U2 can also communicate with external devices through the interface H1.

[0042] Optionally, the current source circuit includes a third operational amplifier U1.3, a fourth operational amplifier U1.4, a first capacitor C1, a sixth resistor R6, a seventh resistor R7, and a tenth resistor R10. The non-inverting input of the third operational amplifier U1.3 is connected to the output of the digital potentiometer U2, and its inverting input is connected to the first terminal of the first capacitor C1 and the first terminal of the sixth resistor R6. The second terminal of the sixth resistor R6 is connected to the second terminal of the first capacitor C1, the first terminal of the seventh resistor R7, and the non-inverting input of the fourth operational amplifier U1.4. The second terminal of the seventh resistor R7 is connected to the output of the fourth operational amplifier U1.4, and the inverting input of the fourth operational amplifier U1.4 is connected to the second terminal of the tenth resistor R10. The first terminal of the tenth resistor R10 is grounded. By using the first capacitor C1 to a certain extent, the phase characteristics of the feedback loop formed by the fourth operational amplifier U1.4 are altered, performing phase compensation to ensure that the feedback loop has sufficient phase margin, avoiding unstable phenomena such as self-oscillation in the circuit, thereby ensuring the stability and accuracy of the output current. The sixth resistor R6 and the tenth resistor R10 together form part of the feedback loop of the fourth operational amplifier U1.4. By properly setting the values ​​of the sixth resistor R6 and the tenth resistor R10, the feedback depth can be adjusted, thereby affecting the gain of the fourth operational amplifier U1.4. Furthermore, the sixth resistor R6 and the fourth resistor R4 together determine the closed-loop gain of the fourth operational amplifier U1.4. Specifically, by selecting a resistance value of 16.5K for both the sixth resistor R6 and the fourth resistor R4, the fourth operational amplifier U1.4 can obtain a suitable gain, thus ensuring that the output current is precisely adjusted as expected within the range of ±18.4mA.

[0043] Optionally, the third operational amplifier U1.3 and the fourth operational amplifier U1.4 can belong to the same operational amplifier as the first operational amplifier U1.1 and the second operational amplifier U1.2. Specifically, two channels of the 4-channel OPA4354AIPWR are connected to the current source circuit to form the third operational amplifier U1.3 and the fourth operational amplifier U1.4 in the current source circuit, and the other two channels of the OPA4354AIPWR form the first operational amplifier U1.1 and the second operational amplifier U1.2.

[0044] Optionally, the current source circuit also includes an eighth resistor R8, a ninth resistor R9, and a second capacitor C2. The first terminal of the eighth resistor R8 is connected to the second terminal of the seventh resistor R7. The second terminal of the eighth resistor R8 is connected to the second terminal of the ninth resistor R9, the second terminal of the second capacitor C2, the output terminal of the fourth operational amplifier U1.4, and the second terminal of the second capacitor C2. The first terminal of the ninth resistor R9 is connected to the second terminal of the tenth resistor R10, the inverting input terminal of the fourth operational amplifier U1.4, and the first terminal of the second capacitor C2. The eighth resistor R8, the ninth resistor R9, and the second capacitor C2 constitute a low-pass filter circuit, which smooths the output current. When the load resistance connected to the current source circuit changes or transient interference occurs in the circuit, the low-pass filter circuit can suppress high-frequency fluctuations in the output current, making the output current more stable, reducing current ripple, improving the performance and reliability of the current source, and meeting the application scenarios with high requirements for output current stability.

[0045] Optionally, the load resistor can be represented as the twelfth resistor R12, which is the final destination of the current. The current source provides the necessary operating current to the load device (such as a sensor) connected to the load resistor by precisely controlling its output current. The load resistor can represent the equivalent resistance of the sensor; the current output by the current source is converted into a corresponding voltage signal via the load resistor for subsequent signal acquisition and processing.

[0046] In one embodiment, the current source circuit constitutes a Howland current source, which converts the voltage signal output by the digital potentiometer U2 into an output current. The output current IOUT is calculated using the formula IOUT = (resistance of the seventh resistor R7 + resistance of the eighth resistor R8) * VW / resistance of the tenth resistor R10 * resistance of the eighth resistor R8, ultimately achieving bidirectional current output within a range of ±18.4mA. To improve the sensitivity of a specific current range, the output voltages VA and VB of the bipolar voltage generation circuit can be reduced by connecting external resistors in series, thereby narrowing the IOUT range while retaining full 10-bit resolution.

[0047] According to one aspect of the embodiments of this application, a digital calibration device is provided, such as... Figure 7 As shown, the digital calibration device may include a sensor and a current source as described in the above embodiment. The output terminal of the current source is connected to the sensor to output current to the sensor. This digital calibration device can be used in scenarios requiring high-precision digital calibration, such as sensor signal conditioning, industrial automation current control, and other fields with high requirements for current output accuracy and stability.

[0048] Alternatively, the sensor can be a temperature sensor, an infrared sensor, a camera, or other sensors that require digital calibration.

[0049] Optionally, the digital calibration device further includes a signal acquisition circuit connected to the sensor for acquiring voltage signals. This signal acquisition circuit may include an analog-to-digital converter (ADC) that acquires the sensor's signals, converts the acquired analog signals into digital signals, and transmits these digital signals to the controller for digital calibration processing.

[0050] The terms "first," "second," "third," "fourth," "1," "2," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than that shown in the illustrations or text descriptions.

[0051] It should be understood that although arrows indicate various operation steps in the flowcharts of this application's embodiments, the order in which these steps are implemented is not limited to the order indicated by the arrows. Unless explicitly stated herein, in some implementation scenarios of this application's embodiments, the implementation steps in each flowchart can be executed in other orders as required. Furthermore, some or all steps in each flowchart, based on the actual implementation scenario, may include multiple sub-steps or multiple stages. Some or all of these sub-steps or stages can be executed at the same time, and each sub-step or stage can also be executed at different times. In scenarios where execution times differ, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and this application's embodiments do not limit this.

[0052] The above description is only an optional implementation method for some implementation scenarios of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application without departing from the technical concept of this application also fall within the protection scope of the embodiments of this application.

Claims

1. A current source, characterized in that, It includes a reference circuit, a bipolar voltage generation circuit, and a voltage conversion circuit connected in sequence. The reference circuit includes a reference voltage source. The reference circuit is used to output a reference voltage to the bipolar voltage generation circuit using the reference voltage source. The reference voltage source includes the model ADR512. The bipolar voltage generation circuit is used to generate a bipolar voltage; The voltage conversion circuit is used to convert the bipolar voltage into current and output it.

2. The current source according to claim 1, characterized in that, The reference circuit includes an eleventh resistor and an eighth capacitor. The first terminal of the reference voltage source is connected to the second terminal of the eleventh resistor and the first terminal of the eighth capacitor. The first terminal of the eleventh resistor is connected to a first power supply. The second terminal of the eighth capacitor is grounded, and the second terminal of the reference voltage source is grounded.

3. The current source according to claim 1, characterized in that, The bipolar voltage generation circuit includes a non-inverting amplifier circuit with a first operational amplifier, a first resistor, and a second resistor. The non-inverting input terminal of the first operational amplifier is connected to the output terminal of the reference circuit. The inverting input terminal of the first operational amplifier is connected to the second terminal of the first resistor and the first terminal of the second resistor. The second terminal of the second resistor is grounded. The first terminal of the first resistor is connected to the output terminal of the first operational amplifier. The power supply terminal of the first operational amplifier is connected to a second power supply.

4. The current source according to claim 3, characterized in that, The bipolar voltage generation circuit includes an inverting amplifier circuit with a second operational amplifier, a third resistor, a fourth resistor, and a fifth resistor. The non-inverting input terminal of the second operational amplifier is connected to the second terminal of the third resistor, the first terminal of the third resistor is grounded, the inverting input terminal of the second operational amplifier is connected to the first terminal of the fourth resistor and the second terminal of the fifth resistor, the second terminal of the fourth resistor is connected to the output terminal of the reference circuit, and the first terminal of the fifth resistor is connected to the output terminal of the second operational amplifier.

5. The current source according to claim 4, characterized in that, The voltage conversion circuit includes a digital potentiometer and a current source circuit. The first voltage input terminal of the digital potentiometer is connected to the output terminal of the first operational amplifier, and the second voltage input terminal of the digital potentiometer is connected to the output terminal of the second operational amplifier. The voltage output terminal of the digital potentiometer is connected to the input terminal of the current source circuit.

6. The current source according to claim 5, characterized in that, The second power supply includes a positive power supply and a negative power supply. The voltage conversion circuit includes a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. The positive power supply is connected to the first terminal of the fifth capacitor, the second terminal of the sixth capacitor, and the working voltage terminal of the digital potentiometer. The second terminals of the fifth capacitor and the second terminals of the sixth capacitor are grounded. The negative power supply is connected to the first terminal of the third capacitor, the first terminal of the fourth capacitor, and the common ground terminal of the digital potentiometer, while the second terminals of the third capacitor and the second terminals of the fourth capacitor are grounded.

7. The current source according to claim 5, characterized in that, The current source circuit includes a third operational amplifier, a fourth operational amplifier, a first capacitor, a sixth resistor, a seventh resistor, and a tenth resistor. The non-inverting input of the third operational amplifier is connected to the output of the digital potentiometer, and the inverting input is connected to the first terminal of the first capacitor and the first terminal of the sixth resistor. The second terminal of the sixth resistor is connected to the second terminal of the first capacitor, the first terminal of the seventh resistor, and the non-inverting input of the fourth operational amplifier. The second terminal of the seventh resistor is connected to the output of the fourth operational amplifier. The inverting input of the fourth operational amplifier is connected to the second terminal of the tenth resistor, and the first terminal of the tenth resistor is grounded.

8. The current source according to claim 7, characterized in that, The current source circuit further includes an eighth resistor, a ninth resistor, and a second capacitor. The first end of the eighth resistor is connected to the second end of the seventh resistor. The second end of the eighth resistor is connected to the second end of the ninth resistor, the second end of the second capacitor, the output terminal of the fourth operational amplifier, and the second end of the second capacitor. The first end of the ninth resistor is connected to the second end of the tenth resistor, the inverting input terminal of the fourth operational amplifier, and the first end of the second capacitor.

9. A digital calibration device, characterized in that, It includes a sensor and a current source as described in any one of claims 1-8, wherein the output terminal of the current source is connected to the sensor for outputting current to the sensor.

10. The digital calibration device according to claim 9, characterized in that, It includes a signal acquisition circuit, which is connected to the sensor and is used to acquire voltage signals.

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