Closed-loop feedback type analog resistance output circuit

Abstract

The utility model belongs to the technical field of analog resistors, and particularly relates to a closed-loop feedback type analog resistor output circuit which comprises a micro-control unit. A sampling resistor; the programmable differential gain amplifier is connected with the sampling resistor and the micro-control unit; the digital-to-analog converter is respectively connected with the programmable differential gain amplifier and the micro-control unit; and the digital potentiometer is connected with the digital-to-analog converter. The micro-control unit monitors and controls each part, continuously digitally adjusts the gain of the programmable differential gain amplifier, the D value of the digital-to-analog converter, the digital voltage division ratio of the digital potentiometer and other parameters, and continuously optimizes the whole analog resistance output process according to feedback signals. Therefore, the highest precision of the analog resistor is ensured to reach 0.01%.

Description

TECHNICAL FIELD

[0001] The present application relates to analog resistance technology, in particular to a closed-loop feedback analog resistance output circuit. BACKGROUND

[0002] The analog resistance output is also widely used in sensor measurement. Common resistance sensors include pressure sensors, temperature sensors and humidity sensors. These sensors reflect the change of the measured physical quantity through the change of the resistance value, and are applied to industrial automation, manufacturing, environmental monitoring and other fields.

[0003] In the related art, the output accuracy of the analog resistance is difficult to reach 0.01%, which cannot meet the use requirements.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those skilled in the art. SUMMARY

[0005] In view of at least one of the above technical problems, the present application provides a closed-loop feedback analog resistance output circuit.

[0006] The present application provides a closed-loop feedback analog resistance output circuit, comprising:

[0007] a micro control unit;

[0008] a sampling resistor for receiving an excitation current and generating an excitation voltage;

[0009] a programmable differential gain amplifier connected with the sampling resistor and the micro control unit, the programmable differential gain amplifier being used to control a gain value by the micro control unit, and the programmable differential gain amplifier being further used to generate a reference voltage according to the excitation voltage and the gain value, the reference voltage being close to a target reference voltage, the target reference voltage being 2.5V;

[0010] a digital-to-analog converter connected with the programmable differential gain amplifier and the micro control unit, the digital-to-analog converter being used to obtain a D value output by the micro control unit, and the digital-to-analog converter being further used to output an output voltage according to the D value and the reference voltage;

[0011] a digital potentiometer connected with the digital-to-analog converter, the digital potentiometer being used to obtain a voltage division ratio and divide the output voltage according to the voltage division ratio, and calculate an analog resistance.

[0012] The technical scheme has one of at least the following advantages or beneficial effects: the micro control unit continuously adjusts the gain of the programmable differential gain amplifier, the D value of the digital to analog converter and the digitalized voltage division ratio of the digital potentiometer and the like parameters through monitoring and control of each part, continuously optimizes the whole analog resistance output process according to the feedback signal, thereby ensuring that the highest precision of the analog resistance reaches 0.01%.

[0013] In a possible implementation, the reference voltage is less than the target reference voltage.

[0014] In a possible implementation, the gain value is 1, 2, 4, 8, 16, 32, 64 or 128.

[0015] In a possible implementation, the micro control unit selects the gain value according to the voltage generated by the sampling resistance and outputs to the programmable differential gain amplifier.

[0016] In a possible implementation, the calculation formula of the reference voltage is:

[0017] V REF = I x R1 x G

[0018] Wherein, V REF is the reference voltage, I is the excitation current, R1 is the sampling resistance, and G is the gain value.

[0019] In a possible implementation, the calculation formula of the output voltage is:

[0020]

[0021] Wherein, V OUT is the output voltage, D is the D value of the digital to analog converter, and V REF is the reference voltage.

[0022] In a possible implementation, the calculation formula of the voltage division ratio is:

[0023]

[0024] Wherein, G1 is the voltage division ratio, and G is the gain value.

[0025] In a possible implementation, the micro control unit is connected with the digital to analog converter through the SPI serial port.

[0026] In a possible implementation, the closed-loop feedback type analog resistance output circuit further comprises: an analog to digital converter, a first end of the analog to digital converter is connected with the programmable differential gain amplifier, a second end of the analog to digital converter is connected with the micro control unit, and the analog to digital converter is used to collect the reference voltage and output to the micro control unit.

[0027] In one possible implementation, the closed-loop feedback analog resistor output circuit also includes an amplifier connected to a numerical potentiometer.

[0028] The present application will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a structural diagram of the closed-loop feedback analog resistor output circuit shown in an embodiment of this application. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] This application is primarily used in pressure sensors and temperature / humidity sensors. Pressure sensors typically operate based on the piezoresistive effect, meaning that changes in pressure cause a change in the resistance of the sensor's internal sensing element; the pressure is indirectly measured by detecting this resistance change. Similarly, some types of temperature / humidity sensors rely on the influence of humidity or temperature on the resistive properties of specific materials to achieve their measurement function. As a key representation of the sensor's signal output, the accuracy of the analog resistor directly determines the accuracy and reliability of the sensor's measurements of physical quantities such as pressure, temperature, and humidity. Therefore, ensuring high-precision output from the analog resistor is crucial.

[0033] like Figure 1 As shown, this embodiment provides a closed-loop feedback analog resistor output circuit, including: a microcontroller unit 100, a sampling resistor R1, a programmable differential gain amplifier 200, a digital-to-analog converter 300, a digital potentiometer 400, an analog-to-digital converter 500, and an amplifier 600.

[0034] The micro control unit 100; a sampling resistor R1 for receiving an excitation current and generating an excitation voltage; a programmable differential gain amplifier 200 connected with the sampling resistor R1 and the micro control unit 100, the programmable differential gain amplifier 200 is used for controlling a gain value by the micro control unit 100, and the programmable differential gain amplifier 200 is also used for generating a reference voltage according to the excitation voltage and the gain value, the reference voltage is close to a target reference voltage; a digital-to-analog converter 300 connected with the programmable differential gain amplifier 200 and the micro control unit 100 respectively, the digital-to-analog converter 300 is used for obtaining a D value output by the micro control unit 100, and the digital-to-analog converter 300 is also used for outputting an output voltage according to the D value and the reference voltage; and a digital potentiometer 400 connected with the digital-to-analog converter 300, the digital potentiometer 400 is used for obtaining a voltage division ratio and dividing the output voltage according to the voltage division ratio to calculate an analog resistor.

[0035] The closed-loop feedback type analog resistor output circuit of the embodiment continuously adjusts parameters such as the gain of the programmable differential gain amplifier 200, the D value of the digital-to-analog converter 300, and the digitalized voltage division ratio of the digital potentiometer 400 through monitoring and control of each part by the micro control unit 100, continuously optimizes the entire analog resistor output process according to the feedback signal, and thus ensures that the highest precision of the analog resistor reaches 0.01%.

[0036] Specifically, the reference voltage is less than the target reference voltage. The target reference voltage is 2.5V, and the reference voltage cannot exceed the target reference voltage.

[0037] Specifically, the gain value is 1, 2, 4, 8, 16, 32, 64 or 128.

[0038] In actual application, the micro control unit 100 selects a gain value according to the voltage generated by the sampling resistor R1 and outputs to the programmable differential gain amplifier 200. It is worth noting that by selecting the gain value, the reference voltage is close to and does not exceed the target reference voltage, so that the reference voltage reaches the best input condition.

[0039] Exemplarily, the excitation current requirement range is 7.5uA-3.0mA, the target reference voltage is 2.5V, assuming that the excitation current is 200uA, the resistance value of the sampling resistor R1 is 2000Ω, the voltage generated by the sampling resistor R1 is 0.2*2000=0.4V, the micro control unit 100 selects the gain value G=4 according to the voltage, and the reference voltage is 4*0.4=1.6V.

[0040] Assuming the excitation current is 3mA, the resistance of the sampling resistor R1 is 2000Ω, the voltage generated by the sampling resistor R1 is 0.3*2000=0.6V, and the micro control unit 100 selects the gain value G=4 according to the voltage, then the reference voltage is 4*0.6=2.4V.

[0041] In addition, in the embodiment, the calculation formula of the reference voltage is:

[0042] V REF =I×R1×G

[0043] wherein V REF is the reference voltage, I is the excitation current, R1 is the sampling resistor R1, and G is the gain value.

[0044] The calculation formula of the output voltage is:

[0045]

[0046] wherein V OUT is the output voltage, D is the D value of the digital-to-analog converter 300, and V REF is the reference voltage.

[0047] The calculation formula of the voltage division ratio is:

[0048]

[0049] wherein G1 is the voltage division ratio, and G is the gain value.

[0050] It is worth noting that the micro control unit 100 determines the voltage division ratio of the digital potentiometer 400 after determining the gain value. At the same time, the minimum resolution of the analog resistor is also determined. Because R=U / I=D*I*R1*G*G1 / 65536 / I=D*R1*G*G1 / 65536, the accuracy of the analog resistor output is related to the sampling resistor R1, the D value of the digital-to-analog converter 300, and the gain value. Therefore, after the micro control unit 100 determines the gain value, the minimum resolution of the analog resistor can also be determined.

[0051] Continuing with the example of an excitation current of 3mA, a sampling resistor R1 resistance of 2000Ω, a gain value G=4, and a reference voltage of 2.4V, at this time, the minimum resolution of the analog resistor is

[0052] D*R1*G*G1 / 65536=1*2000*G*G1 / 65536=1*2000*4*(1 / 8) / 65536=0.015, wherein D is an integer and the minimum is 1.

[0053] When the resistance input value is 50.00Ω, then D=50.00 / 0.015=3333, and the actual output resistance value=3333*0.015=49.995, and the accuracy=0.005 / 50.00=0.01%, reaching the accuracy of 0.01%.

[0054] As shown in Figure 1 , the micro control unit 100 is connected with the digital-analog converter 300 through the SPI serial port. In this way, the data transmission speed can be improved, for example, the transmission speed of the D value of the digital-analog converter 300.

[0055] As shown in Figure 1 , the closed-loop feedback type analog resistance output circuit further comprises an analog-digital converter 500, the first end of the analog-digital converter 500 is connected with the programmable differential gain amplifier 200, the second end of the analog-digital converter 500 is connected with the micro control unit 100, and the analog-digital converter 500 is used to collect the reference voltage and output to the micro control unit 100.

[0056] As shown in Figure 1 , the closed-loop feedback type analog resistance output circuit further comprises an amplifier 600, and the amplifier 600 is connected with the digital potentiometer.

[0057] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into equivalent embodiments without departing from the scope of the technical solution of the present application. Therefore, any equivalent changes made according to the shape, structure and principle of the present application, which do not depart from the technical solution of the present application, should be covered by the protection scope of the present application.

Claims

1. A closed loop feedback analog resistance output circuit, characterized by, The application relates to a closed-loop feedback type analog resistance output circuit. The application relates to a closed-loop feedback type analog resistance output circuit. The application relates to a closed-loop feedback type analog resistance output circuit. The application relates to a closed-loop feedback type analog resistance output circuit. The application relates to a closed-loop feedback type analog resistance output circuit. The application relates to a closed-loop feedback type analog resistance output circuit.

2. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit.

3. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit.

4. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit.

5. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit. V REF = I x R1 x G Wherein, V REF is the reference voltage, I is the excitation current, R1 is the sampling resistance, and G is the gain value.

6. The closed loop feedback analog resistance output circuit of claim 5, wherein, The application relates to a closed-loop feedback type analog resistance output circuit. where V OUT is the output voltage, D is the D value of the digital-to-analog converter, and V REF is the reference voltage.

7. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit. The application relates to a closed-loop feedback type analog resistance output circuit.

8. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit.

9. The closed loop feedback analog resistance output circuit of claim 1, wherein, The application relates to a closed-loop feedback type analog resistance output circuit.

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