A resistance self-correcting circuit and a correction method

Abstract

The application discloses a resistance self-correction circuit and a correction method, and relates to the technical field of circuit correction. cal The resistance test circuit comprises a switch S1, a switch S2, a first operational amplifier, a second operational amplifier, a test resistance R cal ; and the current test circuit comprises a third operational amplifier, a fourth operational amplifier, a switch S3, a switch S4, a switch S5, a switch Sx1 and a test resistance Rx1. cal The application adopts the principle of virtual breaking of the operational amplifier in the resistance test circuit, so that the current of the test resistance R cal is the same as the current of the resistance Rx1, the voltage between the two ends of the test resistance R cal and the voltage between the two ends of the resistance Rx1 are measured, the resistance value of the resistance Rx1 is calculated, the calibration of the resistance Rx1 is completed, the error of the resistance Rx1 is reduced, and the precision of the current test is ensured.

Description

Technical Field

[0001] This invention belongs to the field of circuit testing technology, specifically a resistor self-calibration circuit and calibration method. Background Technology

[0002] Electrochemical current method testing involves applying a certain potential between the counter electrode and the working electrode. An oxidation or reduction current flows through the working electrode. When measuring this current, an operational amplifier converts the current into a voltage, and an analog-to-digital converter (ADC) acquires the test voltage across resistor R. The final current value is obtained using Ohm's law I = U / R. Here, U is obtained through the ADC and is determined by the ADC device itself, while the resistance value R is determined by the raw material itself; high-precision resistors are often selected to meet specific application requirements.

[0003] In the process of current measurement, a wide measurement range and high testing accuracy are required (measurement range 10). -5 Up to 10 -9 A, Measurement accuracy 10 -9 A) This requires using multiple test ranges (multiple high-precision resistors R), selecting different resistor sizes R based on the magnitude of the current being measured. This presents the following problems: 1. Using high-precision resistors to ensure measurement accuracy increases instrument cost; 2. Lowering the resistor accuracy requirement reduces instrument cost but cannot guarantee measurement accuracy. Therefore, a resistor self-calibration circuit and calibration method are proposed to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a resistance self-calibration circuit and calibration method to solve the problem mentioned in the background art that in the prior art, selecting a high-precision resistor can ensure measurement accuracy but increases the cost of the instrument, while selecting a low-precision resistor cannot guarantee measurement accuracy.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A self-calibrating resistor circuit includes a resistance testing circuit and a current testing circuit; wherein the resistance testing circuit is used to connect a calibration resistor to the current testing circuit, and the current testing circuit is used to measure the current.

[0007] The resistance test circuit includes switch S1, switch S2, a first operational amplifier, a second operational amplifier, and a test resistor R. cal One end of switch S1 is connected to the input voltage V. zero The other end of switch S1 is connected to the non-inverting input of the first operational amplifier; the inverting input of the first operational amplifier is connected to the test resistor R. calOne end of the first operational amplifier is connected to the inverting input of the second operational amplifier and one end of the resistor R2; the output of the first operational amplifier is connected to the other end of the resistor R2.

[0008] Test resistor R cal The other end is connected to one end of switch S2, the non-inverting input of the second operational amplifier, and the output of the second operational amplifier, respectively; the other end of switch S2 is connected to the working electrode.

[0009] The current testing circuit includes a third operational amplifier, a fourth operational amplifier, switches S3, S4, S5, Sx1, and a test resistor Rx1; the output terminal of the third operational amplifier is connected to one end of the test resistor Rx1, the other end of the test resistor Rx1 is connected to one end of the switch Sx1, and the other end of the switch Sx1 is connected to the inverting input terminal and the working electrode of the third operational amplifier respectively.

[0010] The non-inverting input of the third operational amplifier is connected to one end of switches S3 and S4, respectively; the other end of switch S3 is connected to the input voltage V. zero Connection; the other end of switch S4 is connected to one end of switch S5, and the other end of switch S5 is connected to the counter electrode and the output terminal of the fourth operational amplifier respectively;

[0011] The inverting input of the fourth operational amplifier is connected to the reference electrode; the non-inverting input of the fourth operational amplifier is connected to the input voltage V. bias connect.

[0012] Based on the above technical solution, the resistance R is tested. cal It is a standard resistor with a resistance of 10K.

[0013] According to the above technical solution, the working electrode is the test probe connected to the test card.

[0014] According to the above technical solution, the reference electrode is the test probe connected to the test card.

[0015] According to the above technical solution, the counter electrode is the test probe in the test card.

[0016] A calibration method for a self-calibrating resistor circuit, comprising the following steps during resistor calibration:

[0017] Step S1, output V through two DACs respectively. zero and V bias ,;

[0018] In step S2, switch S5 is closed, forming a voltage follower circuit with the fourth operational amplifier;

[0019] Step S3: Switch S4 is closed, making the potential at the non-inverting input of the third operational amplifier equal to V.bias They have the same electrical potential;

[0020] Step S4, close switch S x1 The third operational amplifier and resistor Rx1 form a voltage follower circuit, making the potential at the working electrode equal to the potential at the non-inverting input of the third operational amplifier, which is also equal to V. bias The potential;

[0021] Step S5, measure the resistance R respectively. cal Voltage UR at both ends cal and the voltage U across resistor Rx1 Rx1 ;

[0022]

[0023] The resistance value of Rx1 is obtained through calculation:

[0024] Step S6: The calibrated resistor Rx1 is then used for circuit measurement to ensure the accuracy of current measurement.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The method of this invention employs a first operational amplifier, a second operational amplifier, a third operational amplifier, and a fourth operational amplifier to respectively construct a resistance testing circuit and a circuit testing circuit. In the resistance testing circuit, the principle of virtual open circuitry of the operational amplifiers is used to measure the resistance R. cal The current is the same as the current in resistor Rx1. The current in resistor R is obtained by measurement. cal The resistance value of resistor Rx1 is calculated by measuring the voltage across its terminals and the voltage across its terminals, thereby calibrating resistor Rx1, reducing its error, and ensuring the accuracy of subsequent current testing. Attached Figure Description

[0027] Figure 1 This is a circuit diagram for the resistance test of the present invention;

[0028] Figure 2 This is a circuit diagram for the current testing of the present invention;

[0029] Figure 3 This is the overall test circuit diagram of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] like Figure 1 As shown, a self-calibrating circuit and calibration method for resistance include a resistance testing circuit and a current testing circuit; wherein, the resistance testing circuit is used to connect the calibration resistor to the current testing circuit, and the current testing circuit is used to measure the current.

[0033] The resistance test circuit includes switch S1, switch S2, a first operational amplifier, a second operational amplifier, and a test resistor R. cal One end of switch S1 is connected to the input voltage V. zero The other end of switch S1 is connected to the non-inverting input of the first operational amplifier; the inverting input of the first operational amplifier is connected to the test resistor R. cal One end of the first operational amplifier is connected to the inverting input of the second operational amplifier and one end of the resistor R2; the output of the first operational amplifier is connected to the other end of the resistor R2.

[0034] Test resistor R cal The other end is connected to one end of switch S2, the non-inverting input of the second operational amplifier, and the output of the second operational amplifier, respectively; the other end of switch S2 is connected to the working electrode.

[0035] like Figure 2 As shown, the current test circuit includes a third operational amplifier, a fourth operational amplifier, switches S3, S4, S5, Sx1, and a test resistor Rx1; the output terminal of the third operational amplifier is connected to one end of the test resistor Rx1, the other end of the test resistor Rx1 is connected to one end of the switch Sx1, and the other end of the switch Sx1 is connected to the inverting input terminal and the working electrode of the third operational amplifier respectively.

[0036] The non-inverting input of the third operational amplifier is connected to one end of switches S3 and S4, respectively; the other end of switch S3 is connected to the input voltage V. zero Connection; the other end of switch S4 is connected to one end of switch S5, and the other end of switch S5 is connected to the counter electrode and the output terminal of the fourth operational amplifier respectively;

[0037] The inverting input of the fourth operational amplifier is connected to the reference electrode; the non-inverting input of the fourth operational amplifier is connected to the input voltage V. bias connect.

[0038] Test resistor R cal It is a standard resistor with a resistance of 10K.

[0039] The working electrode is the test probe that connects to the working electrode in the test card.

[0040] The reference electrode is a test probe that is connected to the reference electrode in the test card.

[0041] The counter electrode is the test probe connected to the counter electrode in the test card.

[0042] The method of this invention employs a first operational amplifier, a second operational amplifier, a third operational amplifier, and a fourth operational amplifier to respectively construct a resistance testing circuit and a circuit testing circuit. In the resistance testing circuit, the principle of virtual open circuitry of the operational amplifiers is used to measure the resistance R. cal The current is the same as the current in resistor Rx1. The current in resistor R is obtained by measurement. cal The resistance value of resistor Rx1 is calculated by measuring the voltage across its terminals and the voltage across its terminals, thereby calibrating resistor Rx1, reducing its error, and ensuring the accuracy of subsequent current testing.

[0043] Furthermore, the first operational amplifier is... Figure 1 as well as Figure 3 HSTIA in the middle.

[0044] Furthermore, the second operational amplifier is... Figure 1 as well as Figure 3 The excitation amplifier in the middle.

[0045] Furthermore, the third operational amplifier, namely Figure 2 as well as Figure 3 LPTIA in the middle.

[0046] Furthermore, the fourth operational amplifier, namely Figure 2 as well as Figure 3 Pa in the middle.

[0047] Example 2

[0048] This embodiment is a further refinement of Embodiment 1.

[0049] like Figure 3 As shown, V is output through two DACs respectively. zero and V bias The closed switch S5 forms a voltage follower circuit with the fourth operational amplifier (Pa). Because S4 is closed, the potential at the non-inverting input of the third operational amplifier (LPTIA) is equal to V. bias The potentials are the same. Similarly, when switch S is closed... x1Then, a voltage follower circuit is formed between the third operational amplifier (LPTIA) and the resistor Rx1, so that the potential at the working electrode is equal to the potential at the non-inverting input of the third operational amplifier (LPTIA), which is equal to V. bias The potential.

[0050] Test resistor R cal The potential at the point connected to the working electrode is equal to V. bias The potential of the voltage follower circuit formed with the first operational amplifier (HSTIA) causes the test resistor R to... cal The potential at the inverting input of the first operational amplifier (HSTIA) is equal to V. zero Control V zero With V bias The potential difference between them, that is, the potential difference that can be measured by the test resistor R cal A current is formed on the circuit. Due to the principle of "virtual open circuit" in operational amplifiers (virtual open circuit means that under ideal conditions, the current flowing into the input terminal of the integrated operational amplifier is zero), a current flows through the test resistor R. cal The current flowing through resistor Rx1 is the same as that flowing through resistor R. Measure the resistance R... cal Voltage UR at both ends cal and the voltage U across resistor Rx1 Rx1 .

[0051]

[0052] The resistance value of Rx1 is obtained through calculation:

[0053] Similarly, the calibration of Rx2, Rx3, and Rx4 can be completed. (Test resistor R) cal The accuracy of the value is ensured through component selection; a 10K resistor (a high-precision, low-temperature-drift resistor) is selected in the system.

[0054] During current testing, taking the Rx1 range as an example, disconnect switches S1, S2, S4, S5, Sx2, Sx3, and Sx4; close switches S3 and Sx1, and connect the working electrode, reference electrode, and counter electrode into the test flow channel to form the following configuration: Figure 2 The circuit shown.

[0055] The fourth operational amplifier (Pa) forms a feedback loop with the reference electrode and the counter electrode, resulting in a voltage follower circuit that makes the potential on the counter electrode equal to V. bias The potential of . Similarly, the third operational amplifier (LPTIA) and R x1 This forms a voltage follower circuit, making the potential of the working electrode equal to V. zero The potential of V controls bias With V zeroThe potential difference between the control electrode and the working electrode, i.e., the potential difference between the control electrode and the working electrode, creates a current on the working electrode. Due to the principle of "virtual short" in operational amplifiers ("virtual short" means that under ideal conditions, the potentials at the two input terminals are equal), the current I flowing through the working electrode... SE With the flow through R x1 Current I on Rx1 The same, resulting in I Rx1 The current on the electrode is obtained as the current I on the working electrode. SE Measure R x1 Voltage value U at both ends Rx1 Given R x1 The resistance value, I, can be obtained using Ohm's law. Rx1 .

[0056] U RX1 =I RX1 *R Rx1

[0057] Through calculation:

[0058] Among them U RX1 By ensuring sampling accuracy, R RX1 Obtained through calibration, thus making I SE The accuracy has been improved.

[0059] Explanation of technical terms:

[0060] V zero DAC output voltage 1;

[0061] V bias DAC output voltage 2;

[0062] R cal Standard resistor 10K (high precision resistor);

[0063] Working electrode: Connected to the test probe in the test card;

[0064] Reference electrode: Connected to the test probe in the test card;

[0065] Counter electrode: Connect to the test probe in the test card.

[0066] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0067] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A resistor self-calibration circuit, characterized in that: It includes a resistance testing circuit and a current testing circuit; the resistance testing circuit is used to connect the calibration resistor to the current testing circuit, and the current testing circuit is used to measure the current. The resistance test circuit includes switch S1, switch S2, a first operational amplifier, a second operational amplifier, and a test resistor R. cal One end of switch S1 is connected to the input voltage V. zero The other end of switch S1 is connected to the non-inverting input of the first operational amplifier; the inverting input of the first operational amplifier is connected to the test resistor R. cal One end of the first operational amplifier is connected to the inverting input of the second operational amplifier and one end of the resistor R2; the output of the first operational amplifier is connected to the other end of the resistor R2. Test resistor R cal The other end is connected to one end of switch S2, the non-inverting input of the second operational amplifier, and the output of the second operational amplifier, respectively; the other end of switch S2 is connected to the working electrode. The current testing circuit includes a third operational amplifier, a fourth operational amplifier, switches S3, S4, S5, Sx1, and a test resistor Rx1; the output terminal of the third operational amplifier is connected to one end of the test resistor Rx1, the other end of the test resistor Rx1 is connected to one end of the switch Sx1, and the other end of the switch Sx1 is connected to the inverting input terminal and the working electrode of the third operational amplifier respectively. The non-inverting input of the third operational amplifier is connected to one end of switches S3 and S4, respectively; the other end of switch S3 is connected to the input voltage V. zero Connection; the other end of switch S4 is connected to one end of switch S5, and the other end of switch S5 is connected to the counter electrode and the output terminal of the fourth operational amplifier respectively; The inverting input of the fourth operational amplifier is connected to the reference electrode; the non-inverting input of the fourth operational amplifier is connected to the input voltage V. bias connect; When calibrating the test resistor Rx1, the self-calibration circuit is configured to perform the following state reconstruction: The input voltage V is provided by two DACs. zero and V bias ; When switch S5 is closed, a voltage follower circuit is formed between it and the fourth operational amplifier. When switch S4 is closed, the potential at the non-inverting input of the third operational amplifier is equal to that of V. bias They have the same electrical potential; When switch Sx1 is closed, a voltage follower circuit is formed between the third operational amplifier and the test resistor Rx1, making the potential at the working electrode equal to the potential at the non-inverting input of the third operational amplifier, which is also equal to the V... bias The potential; Measure the test resistance R respectively cal Voltage UR at both ends cal And the voltage U across resistor Rx1 Rx1 The resistance value of the test resistor Rx1 is calculated using the following formula: Among them, R cal R is the resistance value of the test resistor R, and Rx1 is the resistance value of the test resistor Rx1.

2. The self-calibrating resistor circuit according to claim 1, characterized in that: Test resistor R cal It is a standard resistor with a resistance of 10K.

3. The self-calibrating resistor circuit according to claim 1, characterized in that: The working electrode is connected to the test probe in the test card.

4. The self-calibrating resistor circuit according to claim 1, characterized in that: The reference electrode is connected to the test probe in the test card.

5. A resistor self-calibration circuit according to claim 1, characterized in that: The counter electrode is connected to the test probe in the test card.

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