阅读说明：本技术 电阻测试电路及电阻测试方法 (Resistance test circuit and resistance test method ) 是由 周健 于 2020-05-21 设计创作，主要内容包括：本发明涉及电阻测量技术领域,提供了一种电阻测试电路及电阻测试方法,用于测量两个被测电阻的电阻差值,该电阻测试电路包括：分压模块,包括串联于供电端与地之间的电流源、标准电阻、第一待测电阻和第二待测电阻；第一测试模块,根据该标准电阻两端的电压生成第一测试电压；第二测试模块,根据该第一待测电阻两端的电压和该第二待测电阻两端的电压生成第二测试电压,其中,该第二测试电压表征该第一待测电阻和第二待测电阻的电阻差值,该电阻测试电路根据该标准电阻的阻值、该第一测试电压和该第二测试电压获得第一待测电阻和第二待测电阻的电阻差值。由此提高了可实现两个被测电阻差值测量的电路的测量精度及该电路的可靠性。(The invention relates to the technical field of resistance measurement, and provides a resistance test circuit and a resistance test method, which are used for measuring the resistance difference value of two tested resistances, and the resistance test circuit comprises: the voltage division module comprises a current source, a standard resistor, a first resistor to be detected and a second resistor to be detected which are connected in series between a power supply end and the ground; the first test module generates a first test voltage according to the voltages at the two ends of the standard resistor; and the second test module generates a second test voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested, wherein the second test voltage represents the resistance difference value of the first resistor to be tested and the second resistor to be tested, and the resistance test circuit obtains the resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage and the second test voltage. Therefore, the measurement precision of the circuit capable of measuring the difference value of the two measured resistors and the reliability of the circuit are improved.)

1. A resistance test circuit for measuring a resistance difference between two measured resistances, the resistance test circuit comprising:

the voltage division module comprises a current source, a standard resistor, a first resistor to be detected and a second resistor to be detected which are connected in series between a power supply end and the ground;

the input end of the first test module is connected with two ends of the standard resistor to form a first path, and a first test voltage is generated according to voltages at two ends of the standard resistor;

a second testing module, the input end of which is connected with the two ends of the first resistor to be tested and the two ends of the second resistor to be tested respectively, and generates a second testing voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested,

the second test voltage represents a resistance difference value of the first resistor to be tested and the second resistor to be tested, and the resistance test circuit obtains the resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage and the second test voltage.

2. The resistance testing circuit of claim 1, wherein the second testing module comprises:

the input end of the first test unit is connected with two ends of the first resistor to be tested to form a second path, and a third test voltage is generated according to the voltage at the two ends of the first resistor to be tested;

the input end of the second test unit is connected with two ends of the second resistor to be tested to form a third path, and a fourth test voltage is generated according to the voltages at the two ends of the second resistor to be tested;

and the input end of the third test unit is respectively connected with the output end of the first test unit and the output end of the second test unit, and the second test voltage is generated according to the third test voltage and the fourth test voltage.

3. The resistance testing circuit of claim 1, wherein the first testing module comprises a first amplifier.

4. The resistance testing circuit of claim 2, wherein the first testing unit comprises a third amplifier, the second testing unit comprises a fourth amplifier, and the third testing unit comprises a second amplifier.

5. The resistance test circuit according to claim 1, wherein the first amplifier, the third amplifier and the fourth amplifier have the same respective amplification gain values, or at least one of the first amplifier, the third amplifier and the fourth amplifier has an amplification gain value different from that of the other two amplifiers.

6. The resistance testing circuit of claim 5, wherein the first amplifier, the second amplifier, the third amplifier, and the fourth amplifier are instrumentation amplifiers.

7. The resistance test circuit of claim 1, wherein the standard resistance is a precision resistance.

8. A resistance testing method is used for measuring the resistance difference value of two tested resistances, and is characterized by comprising the following steps:

applying a preset test current on a series circuit of the standard resistor, the first resistor to be tested and the second resistor to be tested;

acquiring first test voltages at two ends of the standard resistor under the preset test current;

generating a second test voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested under the preset test current;

obtaining a resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage and the second test voltage,

and the second test voltage represents a resistance difference value of the first resistor to be tested and the second resistor to be tested.

9. The method according to claim 8, wherein the generating a second test voltage according to the voltage across the first resistor to be tested and the voltage across the second resistor to be tested at the preset test current comprises:

generating a third test voltage according to the voltages at the two ends of the first resistor to be tested;

generating a fourth test voltage according to the voltages at the two ends of the second resistor to be tested; and

and generating the second test voltage according to the third test voltage and the fourth test voltage.

10. The resistance testing method according to claim 9, further comprising, after generating the second test voltage from the third test voltage and the fourth test voltage:

and acquiring a second gain value of a third test unit generating the second test voltage.

11. The resistance testing method according to claim 9, wherein a first gain value of a first testing module generating the first testing voltage, a third gain value of a first testing unit generating the third testing voltage, and a fourth gain value of a second testing unit generating the fourth testing voltage are the same, or at least one of the three gain values is different from the other two.

12. The resistance testing method according to claim 8, wherein the obtaining of the resistance difference between the first resistance to be tested and the second resistance to be tested according to the resistance value of the standard resistance, the first testing voltage and the second testing voltage comprises:

and obtaining a resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage, the second test voltage and a second gain value of a third test unit generating the second test voltage.

Technical Field

The invention relates to the field of resistance measurement, in particular to a resistance test circuit and a resistance test method.

Background

The resistance is one of basic electrical parameters, and the measuring method is various, and in order to accurately and practically measure the resistance value, the measuring method adopted by different resistances is different from the used instrument.

The current scheme for measuring the difference value of two resistors is to measure the resistance values of the two resistors respectively and then perform subtraction operation. One conventional solution for testing the resistor is to measure the resistance R of the resistor between two nodes of MN according to a resistor testing circuit shown in fig. 1, and this measurement method is called four-wire method resistor testing. The end A is connected with a current source I, the end B is grounded, and the end C and the end D are respectively connected with nodes M and N of the resistor R. And a voltmeter V is connected between the C terminal and the D terminal. The measuring mode can avoid the influence of parasitic resistance between the connecting line AM and the connecting line BN on the test result. The measured resistance value is the ratio of the voltage value measured by a voltmeter V connected with the C end and the D end to the current value flowing through the resistor R.

However, in the Final Test (Final Test) process, the Test accuracy of the resistor is directly limited by the accuracy of the voltmeter and the accuracy of the current source. Generally, the accuracy of a voltmeter with higher accuracy configured on a test machine is 0.05%, and the accuracy of a current source is 0.05%. That is, when measuring voltage and measuring current through a resistor, a random error of five parts per million occurs. According to the existing scheme, the superposition of the two errors can enable the measured resistance value of a single resistor to have a test error close to one in a thousand, and the difference of the two resistance values of the two resistors can cause a two in a thousandth error, so that the measurement requirement of the high-precision resistance value difference value of the resistors can not be met obviously, and meanwhile, the reliability is poor.

Disclosure of Invention

In order to solve the technical problem, the invention provides a resistance test circuit and a resistance test method, which can improve the measurement precision of a difference measurement circuit of two tested resistances and improve the reliability of a test system.

In one aspect, the present invention provides a resistance test circuit for measuring a resistance difference between two measured resistances, the resistance test circuit comprising:

the voltage division module comprises a current source, a standard resistor, a first resistor to be detected and a second resistor to be detected which are connected in series between a power supply end and the ground;

the input end of the first test module is connected with two ends of the standard resistor to form a first path, and a first test voltage is generated according to voltages at two ends of the standard resistor;

a second testing module, the input end of which is connected with the two ends of the first resistor to be tested and the two ends of the second resistor to be tested respectively, and generates a second testing voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested,

the resistance test circuit obtains the resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage and the second test voltage.

Preferably, the second test module comprises:

the input end of the first test unit is connected with two ends of the first resistor to be tested to form a second path, and a third test voltage is generated according to the voltage at the two ends of the first resistor to be tested;

the input end of the second test unit is connected with two ends of a second resistor to be tested to form a third path, and a fourth test voltage is generated according to the voltages at the two ends of the second resistor to be tested;

and the input end of the third test unit is respectively connected with the output end of the first test unit and the output end of the second test unit, and the second test voltage is generated according to the third test voltage and the fourth test voltage.

Preferably, the first test module comprises a first amplifier.

Preferably, the first test unit includes a third amplifier, the second test unit includes a fourth amplifier, and the third test unit includes a second amplifier.

Preferably, the first amplifier, the third amplifier and the fourth amplifier have the same amplification gain value, or at least one of the first amplifier, the third amplifier and the fourth amplifier has an amplification gain value different from the other two.

Preferably, the first amplifier, the second amplifier, the third amplifier, and the fourth amplifier are instrumentation amplifiers.

Preferably, the standard resistor is a precision resistor.

On the other hand, the invention also provides a resistance testing method for measuring the resistance difference value of two tested resistances, which comprises the following steps:

applying a preset test current on a series circuit of the standard resistor, the first resistor to be tested and the second resistor to be tested;

acquiring first test voltages at two ends of the standard resistor under the preset test current;

generating a second test voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested under the preset test current;

obtaining the resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage and the second test voltage,

the second test voltage represents a resistance difference value between the first resistor to be tested and the second resistor to be tested.

Preferably, the generating a second test voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested under the preset test current includes:

generating a third test voltage according to the voltages at the two ends of the first resistor to be tested;

generating a fourth test voltage according to the voltages at the two ends of the second resistor to be tested; and

and generating the second test voltage according to the third test voltage and the fourth test voltage.

Preferably, after generating the second test voltage according to the third test voltage and the fourth test voltage, the method further includes:

and acquiring a second gain value of a third test unit generating the second test voltage.

Preferably, a first gain value of the first test module generating the first test voltage, a third gain value of the first test unit generating the third test voltage, and a fourth gain value of the second test unit generating the fourth test voltage are the same, or at least one of the first gain value, the third gain value, and the fourth gain value is different from the other two.

Preferably, the obtaining of the resistance difference between the first resistor to be tested and the second resistor to be tested according to the resistance of the standard resistor, the first test voltage and the second test voltage includes:

and obtaining a resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage, the second test voltage and a second gain value of a third test unit for generating the second test voltage.

The invention has the beneficial effects that: the invention provides a resistance test circuit and a resistance test method, which apply a preset test current on a series circuit of a standard resistance, a first resistance to be tested and a second resistance to be tested; then obtaining a first test voltage at two ends of the standard resistor under the preset test current; generating a second test voltage according to the voltage at two ends of the first resistor to be tested and the voltage at two ends of the second resistor to be tested under the preset test current; and finally, obtaining a resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage and the second test voltage. The resistance measurement precision of the circuit capable of realizing the measurement of the difference value of the two measured resistances is effectively improved, and meanwhile, the circuit is stable in output, high in response speed and high in reliability.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a prior art resistance test circuit;

FIG. 2 is a schematic diagram illustrating a resistance test circuit according to an embodiment of the present invention;

FIG. 3 illustrates a circuit configuration diagram of the resistance testing circuit shown in FIG. 2;

fig. 4 is a schematic flow chart illustrating a resistance testing method according to an embodiment of the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 2 is a schematic diagram illustrating a structure of a resistance test circuit according to an embodiment of the present invention, and fig. 3 is a circuit structure diagram illustrating the resistance test circuit illustrated in fig. 2.

Referring to fig. 2 and 3, in one aspect, an embodiment of the present invention provides a resistance test circuit 200 for measuring a resistance difference between two measured resistances, where the resistance test circuit 200 includes: the voltage divider module 210 comprises a current source I1, a standard resistor R1, a first resistor R2 to be tested and a second resistor R3 to be tested, wherein the current source I1, the standard resistor R1, the first resistor R2 and the second resistor R3 are connected in series between a power supply end VDD and the ground, the input end of the first test module 220 is connected with two ends A and B of the standard resistor R1 to form a first path, and a first test voltage V1 is generated according to the voltage at two ends of the standard resistor R1; the input end of the second test module 230 is connected to the two ends C and D of the first resistor R2 to be tested and the two ends E and F of the second resistor R3 to be tested, respectively, a second test voltage V2 is generated according to the voltage at the two ends of the first resistor R2 to be tested and the voltage at the two ends of the second resistor R3 to be tested, wherein the second test voltage V2 represents the resistance difference between the first resistor R2 to be tested and the second resistor R3, and the resistance test circuit 200 obtains the resistance difference between the first resistor R2 to be tested and the second resistor R3 to be tested according to the resistance of the standard resistor R1, the first test voltage V1 and the second test voltage V2.

In a preferred embodiment, the second testing module 230 includes: the testing apparatus includes a first testing unit 231, a second testing unit 232, and a third testing unit 233, specifically, an input terminal of the first testing unit 231 is connected to two ends C, D of the first to-be-tested resistor R2 to form a second path, and a third testing voltage V3 is generated according to a voltage at two ends of the first to-be-tested resistor R2; the input end of the second test unit 232 is connected to two ends E, F of the second resistor to be tested R3 to form a third path, and a fourth test voltage V4 is generated according to the voltage at two ends of the second resistor to be tested R3; the input terminal of the third testing unit 233 is connected to the output terminal of the first testing unit 231 and the output terminal of the second testing unit 232, respectively, and the second testing voltage V2 is generated according to the third testing voltage V3 and the fourth testing voltage V4.

In a preferred embodiment, the first test module 220 includes, for example, but not limited to, a first amplifier INA 1.

In a preferred embodiment, the first test unit 231 comprises a third amplifier INA3, the second test unit 232 comprises a fourth amplifier INA4, and the third test unit 233 comprises a second amplifier INA 2.

Further, the amplification gain values of the first amplifier INA1, the third amplifier INA3 and the fourth amplifier INA4 are the same.

It should be noted that the amplification gain values of the first amplifier INA1, the third amplifier INA3 and the fourth amplifier INA4 may be the same, or at least one of the amplification gain values of the first amplifier INA1, the third amplifier INA3 and the fourth amplifier INA4 may be different from the other amplification gain values, which is not limited herein, but in the preferred embodiment of the present invention, the control and adjustment of variables during the test process and the calculation of the test result are facilitated by setting the amplification gain values of the first amplifier INA1, the third amplifier INA3 and the fourth amplifier INA4 to be the same.

In a preferred embodiment, the first amplifier INA1, the second amplifier INA2, the third amplifier INA3 and the fourth amplifier INA4 are instrumentation amplifiers, although the amplification functions corresponding to the first testing module 220, the first testing unit 231, the second testing unit 232 and the third testing unit 233 may be implemented in other manners. For example, each test module or test unit may build an amplifying circuit with the same amplifying function through one or more operational amplifiers, which is not limited herein. In this embodiment, the positive phase input of each instrumentation amplifier can greatly improve the input impedance of the circuit and reduce the attenuation of the circuit to weak input signals; the differential input can lead the circuit to only amplify differential mode signals and only play a following role for common mode input signals, thereby effectively improving the Common Mode Rejection Ratio (CMRR) in the test circuit, improving the test effect and improving the measurement accuracy.

In a preferred embodiment, the standard resistor R1 is a precision resistor, which is a resistance value obtained by testing an eight-bit and half-digital multimeter (the precision of the eight-bit and half-digital multimeter is about 0.0007%, which can meet the requirements of various instrument testing conditions, so that no error can be basically considered to exist), and has low time drift and low temperature drift, and is used in the resistance testing circuit 200 in this embodiment, so that the testing effect can be improved, and the measuring accuracy can be improved.

On the other hand, an embodiment of the present invention further provides a resistance testing method for measuring a resistance difference between two measured resistances, and referring to fig. 4, the resistance testing method includes:

step S110: and applying a preset test current on a series circuit of the standard resistor, the first resistor to be tested and the second resistor to be tested.

In step S110, a preset test current is applied to the standard resistor, the first resistor to be tested, and the second resistor to be tested on the serial line through the current source in the voltage dividing module formed by the current source, the standard resistor, the first resistor to be tested, and the second resistor to be tested which are sequentially connected in series between the power supply terminal and the ground.

Step S120: and acquiring first test voltages at two ends of the reference resistor under the preset test current.

In step S120, a first path is formed by connecting the input terminal of the first test module to two terminals of the standard resistor, and a first test voltage is generated according to a voltage across the standard resistor.

Step S130: and generating a second test voltage according to the voltage at the two ends of the first resistor to be tested and the voltage at the two ends of the second resistor to be tested under the preset test current.

In step S130, a second path is formed by connecting the input terminal of the first testing unit to the two ends of the first resistor to be tested, a third testing voltage is generated according to the voltage at the two ends of the first resistor to be tested, a third path is formed by connecting the input terminal of the second testing unit to the two ends of the second resistor to be tested, a fourth testing voltage is generated according to the voltage at the two ends of the second resistor to be tested, and a second testing voltage is generated according to the third testing voltage and the fourth testing voltage.

Step S140: and acquiring a second gain value of a third test unit generating the second test voltage.

In this embodiment, the first test module includes, for example, a first amplifier, the first test unit includes a third amplifier, the second test unit includes a fourth amplifier, and the third test unit includes a second amplifier. Further, the respective amplification gain values of the first amplifier, the third amplifier and the fourth amplifier are the same, or at least one of the three amplification gain values is different from the other two amplification gain values.

It should be noted that, the respective amplification gain values of the three amplification gain values of the first amplifier, the third amplifier and the fourth amplifier may be the same, or at least one of the three amplification gain values is different from the other two amplification gain values, which is not limited herein, but in the preferred embodiment of the present invention, the control and adjustment of the variables and the calculation of the test result during the test process are facilitated by setting the same amplification gain value of the first amplifier, the third amplifier and the fourth amplifier.

In further embodiments, the first amplifier, the second amplifier, the third amplifier, and the fourth amplifier may be, but are not limited to, instrumentation amplifiers. Of course, the amplification functions corresponding to the first test module, the first test unit, the second test unit and the third test unit can also be realized in other manners. For example, each test module or test unit may build an amplifying circuit with the same amplifying function through one or more operational amplifiers, which is not limited herein.

In step S140, a second gain value of a third amplifier (instrumentation amplifier) in a third test unit that generates the second test voltage is acquired.

Step S150: and obtaining a resistance difference value of the first resistor to be tested and the second resistor to be tested according to the resistance value of the standard resistor, the first test voltage, the second test voltage and a second gain value of a third test unit for generating the second test voltage.

Referring to the resistance test circuit 200 shown in fig. 3, we can obtain:

the output voltage V1 of the first amplifier INA1 in the first test module 220:

V1＝I*R1*G1 (1)

in formula (1), G1 is the amplification gain value of the first amplifier INA1, R1 is the resistance value of the standard resistor R1, I is the current value of the preset test current provided by the current source I1, and further, the standard resistor R1 is a precision resistor;

and, the output voltage V3 of the third amplifier INA3 in the second test module 230:

V3＝I*R2*G3 (2)

in formula (2), G3 is the amplification gain value of the third amplifier, and R2 is the resistance value of the first resistor R2 to be measured;

and, the output voltage V4 of the fourth amplifier INA4 in the second test module 230:

V4＝I*G4*R2 (3)

in formula (3), G4 is the amplification gain value of the fourth amplifier, and in the present embodiment, the amplification gain value G1 of the first amplifier INA1, the amplification gain value G3 of the third amplifier INA3, and the amplification gain value G4 of the fourth amplifier are the same;

and, combining the above equation (2) and equation (3) to obtain the output voltage V2 of the second amplifier INA2 in the second test module 230:

V2＝I*G1*G2*(R2-R3) (4)

in formula (4), R2 is the resistance of the first resistor R2, and R3 is the resistance of the second resistor R3.

Combining the above equations (1) and (4), one can obtain:

after the formula (4) is arranged, the resistance difference value between the first resistance to be measured R2 and the second resistance to be measured R3 is obtained as follows:

in the above equation (6), R1 is the precision resistor, and G2 is the voltage gain value of the second amplifier INA 2. The value of V2/V1 in this equation is the ratio of the two voltages measured by a 0.05% accuracy voltmeter with a maximum error of 0.1%. However, in equation (6) of the calculation (R2-R3), the test error of this ratio is divided by the second gain G2. G2 can be set to 100 times higher, so that the error of test is reduced to 0.001%. That is to say, the test precision of the resistance difference (R2-R3) of the two resistors to be tested can reach 0.001%, the resistance measurement precision of the resistance test circuit capable of realizing the measurement of the resistance difference of the two resistors to be tested is effectively improved, and meanwhile, the circuit is stable in output, high in response speed and high in reliability.

It should be noted that in the description of the present invention, it is to be understood that the terms "upper", "lower", "inner", and the like, indicate orientation or positional relationship, are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referenced components or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

Further, in this document, the contained terms "include", "contain" or any other variation thereof are intended to cover a non-exclusive inclusion, so that a process, a method, an article or an apparatus including a series of elements includes not only those elements but also other elements not explicitly listed or inherent to such process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.